2000 Olds Alero DTC Codes

Hey Guys,

2000 Olds Alero, 100,000 miles, 3.4V6.

I have 3 DTC codes.

P0122 - Throttle Position Sensor Circuit Low Voltage

P0440 - Evaporate Emission System

P0442 - Evap System Small Leak

I have a spair TPS sensor I am going to swap on there. In fact that code is not the one that scares me.

Its the emission ones. P0440 defenition is vague. I bought a used gascap from a junkyard that I am going to put on there, clear the codes, and see what comes back.

I am just wondering if anyone can tell me about any common issues.

Also, does anyone know what the TPS sensor wires are supposed to do at the plug? Which one is ground, which one is the signal, and which one is B+ and is the B+ wire 5v or 12v?

Aside from those issues, I have the "trac off", "ABS", Low Tire Pressure", and Service Vehicle Soon" lights on.

Any suggestions? I have not really had a chance to mess with it yet.

P0122 = low voltage returned from throttle position sensor. Could be a sensor or wiring problem. Grey with black tracer is reference voltage 5VDC. Black is sensor ground, should be less than 5 ohms to ground. Dark blue wire is signal wire to PCM. Should be ~ .5VDC when throttle is closed, and smoothly go to reference voltage when opening throttle to wide open.

P0440 along with the P0442 = EVAP system malfunction. Could be most anything from the fuel cap, filler neck, vent line, vent solenoid, purge solenoid, purge canister, fuel tank, or any of the lines that connect them together.

The trac off, ABS, and tire pressure could all be related to a faulty wheel speed sensor. You need to have the EBCM scanned for codes.

Unless you have definitely confirmed a faulty part, stay away from the boneyard... it's like the proverbial box of chocolates, you never know what you're gonna get.

P0122 = low voltage returned from throttle position sensor. Could be a sensor or wiring problem. Grey with black tracer is reference voltage 5VDC. Black is sensor ground, should be less than 5 ohms to ground. Dark blue wire is signal wire to PCM. Should be ~ .5VDC when throttle is closed, and smoothly go to reference voltage when opening throttle to wide open.

P0440 along with the P0442 = EVAP system malfunction. Could be most anything from the fuel cap, filler neck, vent line, vent solenoid, purge solenoid, purge canister, fuel tank, or any of the lines that connect them together.

The trac off, ABS, and tire pressure could all be related to a faulty wheel speed sensor. You need to have the EBCM scanned for codes.

Unless you have definitely confirmed a faulty part, stay away from the boneyard... it's like the proverbial box of chocolates, you never know what you're gonna get.

Wonderful on the Emission codes!! Thats what I expected to hear I guess.

And your right about the boneyard, but its good for odds and ends.

Thanks for the TPS wiring info, I'll grab a multimeter and see what I have.

Tim,

In order to set the TPS P0122 DTC the TPS signal voltage (output) would have to be less than .1 volt. If the PCM 5v reference is good and you have adequate output at the low reference signal back to the PCM module (1-4 volts) varying the accelerator be sure to check the wiring to the PCM module at the two 80 pin connectors.

TPS Dark Blue wire goes to pin 66 of connector C2. TPS Black wire to pin 61 of C1. See thread below for PCM related work and location.

Click here (http://www.automotiveforums.com/vbulletin/showthread.php?t=894020)

Best to resolve the TPS issue first before working on the others. Also, what is common to the evaporative emissions DTCs is the PCM module and same electrical connectors. Check the fuel tank pressure sensor signals. Good luck!

Thanks Bob, I was wondering that.

The FSM says to connect a scan tool, jumper the 5v reference wire to the signal wire, and turn ignition on. If the scan tool reads 5v on the TPS, the reference and signal wires are good. Then it says to check the resistance of the ground wire to a known good ground.

I think I'll hook up my powrtuner and see what its doing. I wonder if I can watch EVAP systems with it too. Something tells me I can. I bet I can ever watch wheel speed sensor and find out what hub is bad.

I have all this time to diagnose in my head, but limited time to diagnose hands on.

I bet I can ever watch wheel speed sensor and find out what hub is bad.

It could be a hub(s) but on Aleros or Grand Ams check out the electrical connector at the hub and the wiring where it runs along the lower control arm and then the subframe. Then check the big electrical connector at the ABS Motorpack/EBTCM module located on the front left side (driver's) of the subframe. Subject to corrosion.

So I changed the gas cap over, checked the TPS connector. It has good power 5v, and a good ground, so I just swapped on my spair TPS sensor and cleared all the codes.

Then I took it for a spin. TPS light stayed off. WHen I got back I hooked up my code reader again and P0440 was pending. But the P0442 and P0122 were gone.

How should I diagnose P0440? It may just be one of those things I live with. Where are common leak spots on the evap system on alero's? Does O'reilley's or Advnace rent out smoke machines?

P0440 = EVAP system malfunction. Could be most anything from the fuel cap, filler neck, vent line, vent solenoid, purge solenoid, fuel tank pressure sensor, purge canister, fuel tank, or any of the lines that connect them together. The most common cause is a worn out O ring on the fuel fill cap, did you replace the cap with a new one?

Thanks for the info.

I replaced the cap with a used salvege yard one. I want to keep costs as low as possible on this car. Seems odd that two caps would have the same issue. I read a TSB where the o-ring on the sending unit in the fuel tank causes p0440 issues.

I wish I had a smoke machine......

I may just live with the P0440 for now. I think I'll focus on the Trac off, Low Tire Pressure, and ABS lights now.

Unless you have definitely confirmed a faulty part, stay away from the boneyard... it's like the proverbial box of chocolates, you never know what you're gonna get.

Leaky fill cap O ring is very common, so it's very possible you got bad one. New AC Delco caps are not all that expensive.

Ok, I will pick up a new one. I just question ac-delco/GM parts quality recently. Plus my experiances is that its never an easy fix (ie gascap replacement). I wonder if the gascap is the same partnumber on my GTP. I could swap the two. I know mine is good.

A smoking of the EVAP system would prove where the leak is, if there is a leak, and not a sensor problem. I should hook up my tuner and see if I can watch the fuel tank MAP sensor reading.

Either way I could eliminate the code once and for all by just deleting it out of the PCM, so I dont know how much money and time I want to spend on diagnosis.

"We'll give you something to cry about
November 6, 2012
You're next!"

I love it!

But check this out. Today I hooked up my powertuner. Its capable of reading extended GM service codes. P0440 didn't show up. But another one, P1189.

P1189 - Engine Oil Pressure (EOP) Switch Circuit

Does the PCM in this car really monitor oil pressure? All I know is that the Oil pressure light on the dash is there, and is not on. Plus I drove this car all the way home (40 miles) and it is running just fine.

Is this code just a fluke, and where is the oil pressure sensor?

The PCM gets that data from the oil pressure sending unit. The same switch that turns on your oil light. The switch is calibrated to close the contacts when pressure drops below about 7psi. Might want to check oil pressure with a gage, just to be on the safe side. If oil pressure is within specs, I wouldn't worry about it. Was the SES light on? Was the DTC a hard fault, pending fault, or in the history file?

Tim,

I would not depend on the DHP Powertuner for odb-ii diagnostics or how did you modify it? Best to use a good ole odb-ii scanner/scan tool with GM extended codes capability.

BTW - Just in case I have a spare PCM module but for a '02 Alero with 3.4L. Service ID may match.

Was the SES light on? Was the DTC a hard fault, pending fault, or in the history file?

I will check oil pressure, but doesn't that code point towards a circuit problem?

The SES light was not lit, I think it may have been a hard fault but since its a type 3 it didn't illuminate the SES light. (funny how something as inportant as oil pressure wouldn't light the ses light, but I suppose there is a second light)

Tim,

I would not depend on the DHP Powertuner for odb-ii diagnostics or how did you modify it? Best to use a good ole odb-ii scanner/scan tool with GM extended codes capability.

BTW - Just in case I have a spare PCM module but for a '02 Alero with 3.4L. Service ID may match.

I was wondering if its a fluke Bob, I wonder if the powertuner consideres a pending p0440 as a p1189. I have not modified my PCM at all yet. I was going to get the car running good first, but I did download a 2000 Alero DHP 1.5 Bin from the powertuner website. :evillol:

I am not sure what number my service ID is. One of these 6 numbers I assume.....

http://tis2web.service.gm.com/tis2web

Vin = 1G3NL52E8YC344513

I will check oil pressure, but doesn't that code point towards a circuit problem?

The SES light was not lit, I think it may have been a hard fault but since its a type 3 it didn't illuminate the SES light. (funny how something as inportant as oil pressure wouldn't light the ses light, but I suppose there is a second light)

The whole purpose of DTC's is to tell you what circuit malfunctioned, they never tell you to replace a part. Every DTC could potentially be a circuit problem, that's why you follow flow charts to diagnose it. Don't replace any parts unless the flow chart instructs you to do so.

OBDII is there to monitor and help keep emissions low: P1189 is in fact a type 3 DTC and will not illuminate the SES light. If oil pressure drops, and remains at zero while driving, the engine will seize and there won't be any emissions. The tree huggers ought to love that! Isn't that a comforting thought, knowing that you're doing your part to save the planet? ;)

The tree huggers ought to love that! Isn't that a comforting thought, knowing that you're doing your part to save the planet? ;)

Save the planet from what? Global warming? Total conspiracy anyway. If anything the planet has gotten cooler over the past 10 years or so. I remember when in MN, summertime would be 110 and humid for weeks straight. Now we maybe get a week for 90 temps and thats it. We barely use our air conditioning in summer anymore. Heck last year or the year before, we got a foot of snow the second week in june. Oh I was pissed. Had just put a coat of wax on my car and then temps drop to 30's again and it snows two days straight.

But political rants are beside the point. Where is the oil presure sensor on this car for me to install a guage. And I should really change the oil and filter before I test it.

The political crap belongs at our rarely visited Politics Forum at the Off-Topic Forum. :lol:

Tim,

The P1198 DTC is bogus. I see no reference for it for the 2000 or even 2002 Alero with the 3400 V6.

But testing the oil pressure is a good maintenance practice since you don't know the previous status of this car. The oil pressure sending unit is located at the front bank of the engine by the oil filter. Also, if your oil pressure was really an issue the engine would probably make some really strange noises like lifter clatter or excess piston slap which the 3400 is famous for.

I figured that code was bogus. Thanks Bob! Thats the best answer I could get to my question.

No engine noises aside from the regular cold lifter ticks of a 3100/3400 motor.

Speaking of.... A coworker of mine had a 2000 GTP with 70k on it. I would have loved to get my hands on that car, black, black leather, sunroof. I asked to buy it numerous times. He recently got into an accident and totalled it out. So with the money from the insurance company, he bought an 04 grand am 3400. I guess just before he bought it he said the dealer replaced the LIM gaskets. He had it for a couple days and the SES light came on. I scanned it last night at work and came up with a p0301. I cleared the code but had him start the car. I knew what caused the DTC right away. I heard a lifter was obviously collapsed or something. The thing had a horrible valvetrain noise. I mentioned "does it always sound like that?" not wanting to tell him "its got a bad lifter and the LIM needs to come off again". The noise almost completly went away when it warmed up, but a tick/knock that heavy can't be good. The 3100/3400's have always had loud lifters on startup, but this was a heavy metallic sound. Could have been piston slap too I guess. I just cleared the code for him and told him if it comes back on, that I'd take it to the dealer and see if they'd fix it.

Anyways, did you have a chance to run my Vin on that website? Do we have the same Service OSID's?

I figured that code was bogus. Thanks Bob! Thats the best answer I could get to my question.

Did you run my Vin on that website? Do we have the same Service OSID's?

Tim, I'll need the data right off the PCM module versus the VIN. Or see if it matches from mine below.

Serv No.: 12209614 DPKW
HDW No.: 12202600 DPKW

Under the bar code:

*86DPKWM112557NFC8* 12218194

Above is the stock PCM with no issues and excellent condition. Currently in our Alero we have the DHP (Digital Horsepower) re-programmed PCM that I bought outright.

I will have to take a look and see what I have. How much would you have to have for it Bob?