No 3rd or 4th gear - MAXIMA 00

Car is a Maxima SE 2000 with Aut. trans.

Symptoms: Car has erratic transmission operation. Car won't shift in 3rd and 4th gear. 4000rpm at 75km/h, if you push the o/d button and take it of, the transmission slips and engine rev to cutoff. Engine seams to work properly, and idle is good. Shifts from reverse, first to second gear is smooth. But will rev up or get back to first gear without behing needed or with any additionnal throttle.

What I've done so far:
-6 months ago:
Replaced the MAF sensor after an erratic throttle response episode - this was before the transmission problems started occuring. I also cleaned the throttle body at that time and replaced air filter.

-This weekend:
-I adjusted the TPS properly, to get 500ohms closed, and 4000ohms with WOT. Operation is smooth and gradual and you increase throttle.
-Took off the tranny oil pan, took off the solenoids and cleaned everything including the debris magnets at the bottom of the pan. Made the solenoids operate with current and made them "click" properly by cleaning them with compressed air. Tested - works fine. Reinstalled.
-Took out the TCM, opened it, checked for cracks, cold soldering issues and for fried components, board is perfect from the exterior, no issue. Reinstalled.
-Took a look at the crank position sensor under the engine, near the oil pan. Took harness off (was hard to get out), inside of the connector looks clean, no debris or grease. Didn't pull the sensor off tought...

I also did a scan, found the following code:

-P0744 Torque Converter Clutch, Solenoid Circuit Intermittent

I erased the code after I had worked on the car, and went for a test drive. Car still did the exact same thing.

What I suspect now:
-Bad revolution sensor
-Trans. solenoids
-TCM and/or ECM need a reflash / reprogram (considering I adjusted the TPS, changed MAF a while back etc...)

Let's hear what you guys think,

Thx

Actualy, I just brough the car back from the cotage tonight - so I just did 40 miles in 2nd gear!

Man I really tought I had found my problem tonight when I took off the splash guard behind the left front wheel, to get access to the revolution sensor on the tanny... There was a ground wire with a plug at the end hanging loose just beside the suspension. This wire was connected to a terminal under a bolt, on the side of the transmission housing. I put a new terminal on and re-installed it... Erased the code via OBDII, disconnected the battery for 30 minutes... then went for a test drive... same thing again... no 3rd gear...

Couple things I noted on the way back... Trans just don't want to get into 3rd. (and 4th off course...). When I'm in 2nd gear, if I take the O/D off, the transmission disengage and the engine revs... Putting it back ON locks 2nd gear properly again.

When going down hill, if I let the trans in D4, the rpm will just fall back to +/-1000RPM. If I take off the O/D then, there's a little bit of compression/decelaration from the engine which rev up a little...

One other thing, I checked the revolution sensor before bringing the car back tonight - there was some sort of oil on it and very small metal residue (like on the transmission pan magnets...). I cleaned it and reinstaled.

Actualy, I just brough the car back from the cotage tonight - so I just did 40 miles in 2nd gear!

Man I really tought I had found my problem tonight when I took off the splash guard behind the left front wheel, to get access to the revolution sensor on the tanny... There was a ground wire with a plug at the end hanging loose just beside the suspension. This wire was connected to a terminal under a bolt, on the side of the transmission housing. I put a new terminal on and re-installed it... Erased the code via OBDII, disconnected the battery for 30 minutes... then went for a test drive... same thing again... no 3rd gear...

Couple things I noted on the way back... Trans just don't want to get into 3rd. (and 4th off course...). When I'm in 2nd gear, if I take the O/D off, the transmission disengage and the engine revs... Putting it back ON locks 2nd gear properly again.

When going down hill, if I let the trans in D4, the rpm will just fall back to +/-1000RPM. If I take off the O/D then, there's a little bit of compression/decelaration from the engine which rev up a little...

One other thing, I checked the revolution sensor before bringing the car back tonight - there was some sort of oil on it and very small metal residue (like on the transmission pan magnets...). I cleaned it and reinstaled.

If it was poor pwr delivery (bad gnd etc), it would affect all gears. Same with rev sensor...

Every startup the TCU runs self diagnostics - any codes? Likewise, TPS diag can be run via TCU diagnostics...

When rev sensor fails, engine drops into 'safe mode' = 2200 rpm ceiling.

Every gear is controlled via the A/T computer signals. Go verify if the signal pins go up when the 3rd gear should engage. If it does, tranny is possibly mechanically broken (clutch for 3/4?) - as your solenoid pack seems to work...

In the tranny theres also the ctrl valve assembly which might have a jammed/blown seal. At least in my 3gen one could take the valve assy out while tranny sits in place, see illustration. (But then whatdoIknow)

I built a led 'panel' to troubleshoot intermittent kickdown problem, soldered into harness signal wires: each gear displayed by a led. See linky.

Tonight I took the complete valve body that was on the used transmission that I bought and installed it in the car. I also put in a new oil filter and swapped the rev sensor too while at it...

Transmission does the exact same thing as before :/


Either the TCM is fried or it's a mecanical problem in the transmission...


The only thing I find weird is that the transmission still goes from 2nd to 1rst whitout any reason, as if it had no reference of speed or "power demand"... If it wasn't for that, I'd bet on a mecanical trans. problem...

Tonight I took the complete valve body that was on the used transmission that I bought and installed it in the car. I also put in a new oil filter and swapped the rev sensor too while at it...

Transmission does the exact same thing as before :/


Either the TCM is fried or it's a mecanical problem in the transmission...


The only thing I find weird is that the transmission still goes from 2nd to 1rst whitout any reason, as if it had no reference of speed or "power demand"... If it wasn't for that, I'd bet on a mecanical trans. problem...


So you have problems on all gears - that totally changes the chart:
- measure the rev sensor, should be one volt or more at 19mph. Rises linearly when speed goes up.

Take good known multimeter, attach it securely on the dash. Ground one probe properly. Solder extension wire to a paperclip, push it into the A/T connector plug from rear. Attach the second probe, turn dial to DC voltage. (First find the correct pin.) Go for a ride.

Check likewise also the TPS signal...

First of all, see that the A/T computer gets full charge power: has to be over 13,5V while engine running.

...

First of all, see that the A/T computer gets full charge power: has to be over 13,5V while engine running.


Try to get the FSM....



------------------------------------------------------------

The A/T system has two self-diagnostic systems.

The first is the emission-related on board diagnostic system (OBD-II) performed by the TCM (transmission
control module) in combination with the ECM. The malfunction is indicated by the MIL (malfunction indicator
lamp) and is stored as a DTC in the ECM memory but not the TCM memory.
The second is the TCM original self-diagnosis indicated by the O/D OFF indicator lamp. The malfunction is
stored in the TCM memory. The detected items are overlapped with OBD-II self-diagnostic items. For detail,
refer to AT-52.

OBD-II Function for A/T System
The ECM provides emission-related on board diagnostic (OBD-II) functions for the A/T system. One function
is to receive a signal from the TCM used with OBD-related parts of the A/T system. The signal is sent to the
ECM when a malfunction occurs in the corresponding OBD-related part. The other function is to indicate a
diagnostic result by means of the MIL (malfunction indicator lamp) on the instrument panel. Sensors, switches
and solenoid valves are used as sensing elements.
The MIL automatically illuminates in One or Two Trip Detection Logic when a malfunction is sensed in relation
to A/T system parts.

ONE TRIP DETECTION LOGIC
One or Two Trip Detection Logic of OBD-II
If a malfunction is sensed during the first test drive, the MIL will illuminate and the malfunction will be stored
in the ECM memory as a DTC. The TCM is not provided with such a memory function.

TWO TRIP DETECTION LOGIC
When a malfunction is sensed during the first test drive, it is stored in the ECM memory as a 1st trip DTC
(diagnostic trouble code) or 1st trip freeze frame data. At this point, the MIL will not illuminate. — First Trip
If the same malfunction as that experienced during the first test drive is sensed during the second test drive,
the MIL will illuminate. — Second Trip
A/T-related parts for which the MIL illuminates during the first or second test drive are listed below.

MIL
One trip detection Two trip detection
Shift solenoid valve A — DTC: P0750 (0750) X
Shift solenoid valve B — DTC: P0755 (0755) X
Throttle position sensor or switch — DTC: P1705 (1705) X
Except above X
The “trip” in the “One or Two Trip Detection Logic” means a driving mode in which self-diagnosis is performed
during vehicle operation.




Diagnostic Procedure Without CONSULT-II
OBD-II SELF-DIAGNOSTIC PROCEDURE (WITH GST)
Refer to EC-109, “Generic Scan Tool (GST)”.
OBD-II SELF-DIAGNOSTIC PROCEDURE (NO
TOOLS)
Refer to EC-89, “Malfunction Indicator Lamp (MIL)”.
TCM SELF-DIAGNOSTIC PROCEDURE (NO TOOLS)
Preparation
1. Turn ignition switch to “OFF” position.
2. Connect the handy type vacuum pump to the throttle opener
and apply vacuum –25.3 kPa (–190 mmHg, –7.48 inHg).
3. Disconnect the throttle position switch harness connector.
4. Turn ignition switch to “ON” position.
5. Check continuity of the closed throttle position switch.
Continuity should exist.
(If continuity does not exist, check throttle opener and
closed throttle position switch. Then increase vacuum
until closed throttle position switch shows continuity.)
6. Go to “DIAGNOSIS START” on next page.




1 CHECK O/D OFF INDICATOR LAMP
1. Move selector lever to P position.
Start engine and warm it up to normal engine operating temperature.
2. Turn ignition switch to OFF position.
3. Wait 5 seconds.
4. Turn ignition switch to ON position.
(Do not start engine.)
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Diagnostic Procedure Without CONSULT-II (Cont’d)
5. Does O/D OFF indicator lamp come on for about 2 seconds?
YesorNo
Yes © GO TO 2.
No © Stop procedure. Perform “1. O/D OFF Indicator Lamp Does Not Come On”, AT-219
before proceeding.

P.219 CHECK POWER SOURCE STEP 2
1. Turn ignition switch to OFF position.
2. Check voltage between TCM terminal 28 and ground.

P.220 CHECK TCM GROUND CIRCUIT
1. Turn ignition switch to OFF position.
2. Disconnect TCM harness connector.
3. Check continuity between TCM terminals 25, 48 and ground.

CHECK LAMP CIRCUIT (if no light)
1. Turn ignition switch to OFF position.
2. Check resistance between TCM terminals 10 and 13.
Resistance: 50 - 100Ω


Description
The revolution sensor detects the revolution of the idler gear parking
pawl lock gear and emits a pulse signal. The pulse signal is sent
to the TCM which converts it into vehicle speed.

TCM TERMINALS AND REFERENCE VALUE No.
Wire color Item Condition
29 W Revolution sensor
42 B Throttle position sensor (Ground)

When moving at 20 km/h (12 MPH), use the CONSULT-II pulse frequency measuring function.*1
CAUTION:
Connect the diagnosis data link cable to the vehicle diagnosis connector.
*1: A circuit tester cannot be used to test this item.
Judgement standard 450 Hz (Approx.)
When vehicle parks. Under 1.3V or over 4.5V



TCM INSPECTION TABLE (Data are reference values.)
Wire color Item Condition Judgement
1 G/R
Line pressure solenoid valve
2 W/B
Line pressure sole-noid valve (with dropping resistor)
3 G/B
Torque converter clutch solenoid valve
10 R/Y Power source or When turning ignition switch to ON.
11 R/Y Shift solenoid valve A
12 LG/B Shift solenoid valve B
13 G/Y O/D OFF indicator lamp
16 GY/L Closed throttle position switch (in throttle position switch)
17 P Wide open throttle position switch (in throttle position switch)
18 Y ASCD cruise switch
9 R/Y Power source Same as No. 10
20 BR/Y Overrun clutch solenoid valve
22 G/Y Overdrive control switch
24 L ASCD OD cut sig- nal
25 B Ground
26 PU/W
PNP switch 1 posi-
27 P/B
PNP switch 2 posi-tion
28 Y/R Power source (Memory back-up)
29 W Revolution sensor
30** BR/Y Data link connector
31** P Data link connector
32 R Throttle position sensor (Power source)
33* Y/B LAN
34 Y/PU PNP switch D posi-
35 G/W PNP switch R posi-tion
36 R/G PNP switch P or N position
39 W/G Engine speed sig-nal
40 PU/R Vehicle speed sen-sor
41 W Throttle positionsensor
42 B Throttle position sensor (Ground)
45 R/G Stop lamp switch
47 G A/T fluid tempera- ture sensor
48 B Ground

AT-95

So you have problems on all gears - that totally changes the chart:

I'd still say that the first two gear works properly as they shift fine and smooth under WOT acceleration. When the transmission shift back from 2nd to 1rst gear, it's while driving slow or under very light acceleration.

One other thing, when the car stayed in second gear for the first time, the car had been parked for two weeks. Is it possible that the battery had fallen a little low on voltage, and when the car started up for the first time, the TCM didn't get the proper voltage and it fried, or just "unprogramed" itself ?

Thx a lot for the procedure by the way, I'll look into it and post back. I know that the O/D light doesn't show up on startup tought.

Google words, nicoclub.com/fsm for factory service manual

Yep, already had the FSM for the AT. Thx for the link tought, I didn't had the complete list. :)

Couple things noted during the procedure described in the previous post by Nahkapohjola.

Yes, my O/D light do light up for 2 second when you turn the ignition ON. (What does that mean ??)

I did all the test appart from the TPS one, as I didn't had a vacuum pump...

The ground terminals are OK. There is voltage at pin 28 (altought it's pretty low, 12.05V. I think by battery is gone...). There is continuity between pin 25, 48 and ground.

Now, with the ignition switch OFF (as stated in the procedure), I was not able to get a resistance reading between pin 10 and 13. I tried to turn the ignition ON and then I did get a reading of aprox 100Ω. (NORMAL?? Error in the procedure??)

Couple things noted during the procedure described in the previous post by Nahkapohjola.

"Yes, my O/D light do light up for 2 second when you turn the ignition ON. (What does that mean ??)
-- self diagnostics passes through. It runs every time ign is turned ON. All the problems that factory nerds could think of some 15 yrs ago, seem to be ok... However, they could figure out only 5% - and thats optimistic.

"I did all the test appart from the TPS one, as I didn't had a vacuum pump...
-- Also this procedure is in most cases unnecessary. Here truly not needed.

"The ground terminals are OK. There is voltage at pin 28 (altought it's pretty low, 12.05V. I think by battery is gone...). There is continuity between pin 25, 48 and ground.
-- Ground test is imperative. When engine off, that voltage is ok. If engine is idling=charging, there should be 13,5V minimum or the TCM may behave erratically. What is the voltage att battery while idling? Does revving change that reading?

"Now, with the ignition switch OFF (as stated in the procedure), I was not able to get a resistance reading between pin 10 and 13. I tried to turn the ignition ON and then I did get a reading of aprox 100Ω. (NORMAL?? Error in the procedure??)
-- its the LAMP resistance. All the FSM procedures are done by imbeciles and are over 95% useless: if you see the lamp, then no need to test if the lamp is ok. Huh!? (Note: I just cut a large chunk off the manual, edited, pasted above)

No wonder they charge gold at stealership service; all these japanese confuzing bow down procedures hog 95% of the effective troubleshoot time... You pay 95% for rituals: Cheaper, as effective is to open da hood, give horses (engine) sun tanning therapy. However, if there is a specific known fix to do, it may be feasible to let a stealership do it - just demand all 'used parts' afterwards, and tell that I'll inspect em :)

Weird thing I just noticed while doing a simple test... I charged my battery overnight. And this morning I had 13.74V on the battery. I had the same thing on pin #28 on the TCM...

Then I started the car and the voltage fell to 12.5 on the TCM.... and even lower after 30 seconds... fell to 12.1 I think...

I'll look at the alternator this morning... but there's clearly something wrong in loosing voltage when the car's running... ??

Might be a short sipping all the juice? Or the alternator is just gone... But, it seamed to charge the battery fine since I put the car back on the road a couple weeks ago.

...

Might be a short sipping all the juice? Or the alternator is just gone... But, it seamed to charge the battery fine since I put the car back on the road a couple weeks ago.

There are myriad reasons for voltage drop - and have to be corrected first before one can expect the computers to run correctly. Typically maxima charge voltage at battery is steady sharp 14.2V while engine running on 'any' rpm.

If battery was good yesterday, it doesnt mean its good today. They can be intermittenlty causing problems... However, see the CDomain alternator, groundings linky's click below.

If you havent lately serviced connections, my guess is that alt is bad/disconnected and/or floating or supply and/or batt wires are oxidized: short will eventually produce smoke, a (oxidated) disconnect just discomford...

This morning, I was trying to find the cause of my low voltage... I cleaned both battery post and the terminals... Still voltage is in the high 11V range and now I have the battery sign lit up in the dash...

I'll try to get an output reading on the alternator tomorrow...

I also did a lot of tests on the TCM. All voltage or ohm reading seams to be within spec, expect one. The signal from the "Vehicule speed sensor" on pin #40.

This is what they say:

-Check voltage between TCM terminal 40 and ground while driving at 2 to 3 km/h (1 to 2 MPH) for 1 m (3 ft) or more.

Voltage varies between less than 1V and more than 4.5V.


I tested mine and it jump all over the place. I get all sorts of readings ranging from 0 to 5V. (2.1V, 3.5V, 3.65V etc...). They say it should either be under 1V, or over 4.5V and mine doesn't do that... Even when the car is stopped, it still show 4.5 or 4.6 volts readings! (??)

Now when they say DTC VEHICLE SPEED SENSOR·MTR, what part are they reffering to? The transmission rev sensor, abs sensor, speed sensor in the speedo cluster ???

Again, thx for the help.

This morning, I was trying to find the cause of my low voltage... I cleaned both battery post and the terminals... Still voltage is in the high 11V range and now I have the battery sign lit up in the dash...

I'll try to get an output reading on the alternator tomorrow......

Not ABS. Theres one sensor for 'ground speed' that goes to speedo, one for tranny, one engine rpm input.

The rev sensor gives square lo/hi pulses - which are painful to observe on digital multimeter display. You need a oscilloscope; however, my bet is that what you see means the sensor is alive and well enough.

Your alt and/or batt has been dying... Causes listed in my CDomain alt section, click below, theres also a writeup for 2k2 maxima alt swap. Pls read. As stated, the alt may be intermittently floating (loosing ground contact) and frying voltage regulator thus ruining battery with 20VAC or over. Repair/swap alt ... extra gnd cable between alt shroud and chassis gnd is one good solution not to repeat the problem.

Its not first time I hear low voltage supply making tranny ctrl go haywire. This is why (look my first post) every-any-whatever troubleshooting starts from charge voltage check - ridiculously missing in the confuzean flowcharts...

Even when the car is stopped, I get clear and long reading of 4.5V from the vehicule speed sensor terminal (#40) ? Why does it stay there?

Also for the alternator, I see that the regulator in built in the alternator on mine (it looks like it, haven't checked the specs). Would it be good to check the ground (or add one) before replacing it?

One last one, when a regulator get toasted, does the voltage always go up at the battery terminals ?

Because when I start the car, my V. reading seam to get lower...

Even when the car is stopped, I get clear and long reading of 4.5V from the vehicule speed sensor terminal (#40) ? Why does it stay there?

Also for the alternator, I see that the regulator in built in the alternator on mine (it looks like it, haven't checked the specs). Would it be good to check the ground (or add one) before replacing it?

One last one, when a regulator get toasted, does the voltage always go up at the battery terminals ?

Because when I start the car, my V. reading seam to get lower...

- For the sensor, the TCU is the supply-source 'route' for power. The 'sensor' chops this voltage signal each time magnet passes it and gives the chopped signal as the output. Thus rotation causes square wave output; the wave amplitude - or 'square length' related with speed. No movement = no chopping... Depends on sensor type and/or magnet position what the output happens to be while stationary.

- add jumper wire from alternator into chassis = test grounding. However, I suspect your alt has already passed.

ALTERNATOR
- yes your alternator contains the rectifier and voltage regulator. But you can buy them separately. If you like tinkering, DIY. Swap new bearings also...
- brushes wear out 'at 100k miles' = warning lamp comes on flickering or full, meaning no charge.
- Theres the writeup linky below how to change the brushes (older 3gen model, but no big diff with 4gen maxima) ... and/or the regulator.
- Go buy smtg new: Brushes few dollars, regulator 50$, replacement 'factory repaired' alt 200$, new 2000$.... approx.
- You have to open it to see if brushes are worn. You may buy just the brushes, or the regulator assy with brushes - and swap. Remember the dust cleanup which may be shorting tha alt rectifier diodes. Stupid copper-dust 'feature' like most cheap issues in our vehicles. This issue may hamper 'any' vehicle driven over 60k.
- Most people buy another alt. I changed brushes because $$$ and I wanted to keep the original alternator - as the factory repaired tend to last one year - possibly problem with oxidation due to ? harsh cleaning fluids for the used alu shrouds at repair-factory... read the writeup and how to go around that problem.

When engine is started, it always consumes power to keep it running. All kinds of peripherals suck power along with ignition, computers... If no charge, then power is taken from battery. This means batt voltage surely drops, engine will die ... in an hour?
Low voltage: The tranny computer TCU seems to be the first to become asthmatic ... far earlier than the engine ECM: possibly logic ? uses IC's with 12v supply features.

I cleaned all ground terminals in the engine bay today. I also cleaned the alternator + post and properly re-did my battery post connections so they are tight and firm.

Battery read 12.6V, after starting the car, reads 13.5 / 13.6V... good sign... (lets hope it last...)

I also did some tests again with the TCM. I went on the road and monitored the Shift solenoid A and B terminals with a multimeter. As expected, they come On and OFF depending on the gear you select. They seam to work fine. I tested the TPS and switch again, all is within specs. This kind of point out to either a mechanical tranny problem, or the TCM that might still be fried or unprogrammed....

Again, what makes me believe that there's a "software" issue with the car is that the transmission drop back from 2nd to first gear whitout notice or being needed... Also, let's say I'm doing 75km/h and I punch the gaz, it'll try to engage 1rst gear even if the car is traveling way too fast... that makes me believe that the TCM has an improper "speed" refference somehow... I already swapped the rev sensor, I tested it also with a multimetter so I know it's alive. My abs and speedo works properly... I just don't know where to look now... There should be a "vehicule speed sensor" on the trasmission, just not 100% sure where to look...SOme say on top of the differential... I tested it's terminal on the TCM while on the road but it gave me all sorts of voltages... Don't know if they're good or not...

Can the ECM be unprogramed or fried and sending wrong data to the TCM ?

Is it possible to flash (reprogram) a TCM ??

I cleaned all ground terminals in the engine bay today. I also cleaned the alternator + post and properly re-did my battery post connections so they are tight and firm.

Battery read 12.6V, after starting the car, reads 13.5 / 13.6V... good sign... (lets hope it last...)

I also did some tests again with the TCM. I went on the road and monitored the Shift solenoid A and B terminals with a multimeter. As expected, they come On and OFF depending on the gear you select. They seam to work fine. I tested the TPS and switch again, all is within specs. This kind of point out to either a mechanical tranny problem, or the TCM that might still be fried or unprogrammed....

Again, what makes me believe that there's a "software" issue with the car is that the transmission drop back from 2nd to first gear whitout notice or being needed... Also, let's say I'm doing 75km/h and I punch the gaz, it'll try to engage 1rst gear even if the car is traveling way too fast... that makes me believe that the TCM has an improper "speed" refference somehow... I already swapped the rev sensor, I tested it also with a multimetter so I know it's alive. My abs and speedo works properly... I just don't know where to look now... There should be a "vehicule speed sensor" on the trasmission, just not 100% sure where to look...SOme say on top of the differential... I tested it's terminal on the TCM while on the road but it gave me all sorts of voltages... Don't know if they're good or not...

Can the ECM be unprogramed or fried and sending wrong data to the TCM ?

Is it possible to flash (reprogram) a TCM ??

13.5V is not good AT BATTERY... It means TCU voltage too low. Work on it until you get 13.8V -or- the normal 14.2V. First things first: Low power means semi paralyzed logic.

Charge voltage - 14.2Volts at battery mean 13.5Volts at TCU, which is healthy. Anything less and youre wasting your time in this case... On 'normal non problematic vehicle' 13.8Volt can be accepted, if new alternator swap 'is to be scheduled'.



Everything is possible, however, no procedures exist. If you take eproms out, UV-erase, and have a eprom programmer, it can be done. But where would u get any better program...?

ECM & TCU work in tandem, surelly affect each other. How they do it, I dont know of any info given... Try to swap. But with low power, no point.

ECM has one basic datatable. Then it has second datatable used in 'learning'. FSM depicts the 20minute learning drive with various drive 'phases'. This ECM memory is cleared via taking batt off 30min or more... This feature basically re-tunes new swapped MAF signal handling with the rest inputs: all the low grade MAF units are individuals 'having their own lifestyle' and their output signals like blondies. However, ECM learns in 'four' hours of normal drive, cleaned=learning ECM gives more jerky drive.

Btw. If power is at loss, clean the MAF and clear ECM as depicted...

Just want to specify that the 13.5V I got at the battery was with both + and - terminals connected as usual on it. To test the alternator output voltage, should I unplug the + terminal and test on it directly, whitout it being connected on the battery? (to make sure)

Also, the warning "battery" light in the dash went away.

Bit I agree, I would expect to see closer to 14V coming from a healty alternator....

Just want to specify that the 13.5V I got at the battery was with both + and - terminals connected as usual on it. To test the alternator output voltage, should I unplug the + terminal and test on it directly, whitout it being connected on the battery? (to make sure)

Also, the warning "battery" light in the dash went away.

Bit I agree, I would expect to see closer to 14V coming from a healty alternator....

Batt pole tst is ok. However, there is a brewing problem. Before swapping alt, verify your reading with another multimeter, maybe the fault is there. Would not be the first time...

As depicted, the alt two connector pins itself can be loose. Check.

A quick update.

I replaced the battery and now I get a very good voltage reading from the alt and bat. 14.7V +

When for a quick drive, car does the same thing.

One question: when the engine is warm, if I give it some throttle (anywhere from 10% up to 50% I'd say), the rpm will over around 1600-1700rpm as if it was in cutoff mode. Going up to 1700RPM then quickly back to 1600rpm while the ignition seams to momentarely cut, then back and forth over and over again...

What is that? I suspect the closed throttle position sensor but might be wrong... What do you guys think?

A quick update.

I replaced the battery and now I get a very good voltage reading from the alt and bat. 14.7V +

When for a quick drive, car does the same thing.

One question: when the engine is warm, if I give it some throttle (anywhere from 10% up to 50% I'd say), the rpm will over around 1600-1700rpm as if it was in cutoff mode. Going up to 1700RPM then quickly back to 1600rpm while the ignition seams to momentarely cut, then back and forth over and over again...

What is that? I suspect the closed throttle position sensor but might be wrong... What do you guys think?

- you have to run diagnostics, maybe some sensor dead. That drops engine into 'safe-mode' with rpm limit?
- buy a 100$ diag tool displaying all CEL codes. Find one which may be always on, while displaying all valid current codes plus error codes.

- Throttle pos sensor TPS, engine uses only when warm ... (however, tranny 'needs it')

The engine is not in safe mode I think. The rpm fluctuate when the engine is warm and I press the trottle when in park, anywere from 5% up to 50% aprox. On the road, I don't feel any hesitation.

If I press more than 50%, the RPM climb normaly up to redline. Also, If I quickly blip full trottle, it'll take it just fine. It's just that 5-50% part that makes the engine cutoff at 1700rpm somehow...

I already pulled the codes, I had one for the canister valve near the gaz tank (repaired), and -P0744 Torque Converter Clutch, Solenoid Circuit Intermittent

The engine is not in safe mode I think. The rpm fluctuate when the engine is warm and I press the trottle when in park, anywere from 5% up to 50% aprox. On the road, I don't feel any hesitation.

If I press more than 50%, the RPM climb normaly up to redline. Also, If I quickly blip full trottle, it'll take it just fine. It's just that 5-50% part that makes the engine cutoff at 1700rpm somehow...

I already pulled the codes, I had one for the canister valve near the gaz tank (repaired), and -P0744 Torque Converter Clutch, Solenoid Circuit Intermittent

"I press the trottle when in park"
- only in park?
- cold = ok?

Full throttle blip bypasses O2 input. The 02 sensors on 99% of cars are cheap and cant follow full gas flow, thus computer uses a datatable and compares it to rpm signal when controlling injectors.

Warm: No TPS used in engine mgmt. Instead O2 feedback is the main input (+MAF & rpm) to determine how injectors are controlled.

Test: while in Park, pull MAF connector plug out. This will cause 2.2k rpm ceiling - but your 1700rpm hesitation will be gone if MAF is bad. Push the plug back in...

Possibly O2 signal(s) warped. Signal, computer problem... Or maybe exhaust pipe leaking = oxygen seeps in distorting O2 signal.

However, diagnostics should indicate when O2 signal is amiss. Run the diagnostics. Pull the rhe diag codes, could ? be different. Anyways, diagnostics use the 3rd O2 sensor - which is maybe only used in diagnostics only. Dunno, the jap FSM translation isnt too accurate. You know service manual blondies syndrome.

Whatever, first ensure full voltage at both computers, TCU, ECM.

I have exact problem with my gear box!!
I hope you had fixed your tranny problem.

My gear box goes 1-2-2-1, not 1-2-3-4 as it should be.
All other parts in the car are in excellent condition, I suspect solenoid A and/or its valve (in the tranny box) is not working!
I shall drop them and have a look around....

Have you been able to figure out the problem? I just bought an 01 Pathfinder with the same exact issue. It will shift from 1st to 2nd smoothly but won't shift to 3rd or OD. I tested with my OBDII scanner and get 2 crankshaft position codes. One code for the sensor itself and one for circuit A. Codes p1335 and p0335.

Would that cause transmission troubles like i explained?