95 Blazer 4x4

I'm having a problem with my 95 blazer, when i switch into 4hi i here the seloniod moving but im not going into 4x4,anyone have any sugestions?
joe

Any trouble codes? Heard of the pin 13 test? Fuse ok? Fluid level good? Fluid clean? Recent / any tranny service? Are you trying to shift from 2hi to 4hi or 4lo?

Any trouble codes? Heard of the pin 13 test? Fuse ok? Fluid level good? Fluid clean? Recent / any tranny service? Are you trying to shift from 2hi to 4hi or 4lo?
Well the fluid an fuse are ok, no recent tranny service i havnt heard of the 13 pin test,the service lite did come on i didnt no if its related though
Joe

Is your PCM (black box dealy) on top of your coolant barftank? If so you're OBD II and this will apply to you.

You can use a trans capable scanner or the pin 13 test as follows to get any DTCs stored:


1. Position the ignition switch to OFF. Ensure the ignition switch is positioned to OFF for at least 6 seconds.

2. Connect pin 13 on the data link cable to a vehicle ground source. The data link connector is located in the cab under the instrument panel on the drivers side.

3. Position the ignition switch to RUN.
Note the shift select buttons for blinking codes. Refer to Diagnostic Trouble Codes .

If the shift select buttons all blink one time and stop, and do not continue to blink, no fault codes are stored in the TCCM.
The transfer case shift select buttons will blink in order to identify any stored DTC. If only one code is stored in the TCCM memory, that code will blink repeatedly with a three second delay between blinking sequences. If more than one code is stored, the first code will blink once, then after a three seconds delay, the next code will blink. This sequence will continue until pin 13 is no longer grounded.

When reading the diagnostic trouble codes, the number of shift select buttons blinks will indicate the code number.

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Diagnostic Trouble Code (DTC) 1
When the ignition switch is positioned to RUN the TCCM test to determine if RAM standby Power (maintained battery power) to the TCCM was lost since the ignition was last turned OFF. When power is interrupted on pin C6 of the TCCM, the TCCM stores a loss of RAM standby power.

Diagnostic Trouble Code (DTC) 2
During electronic shifting, the TCCM check the motor/encoder for normal operation. If the motor/encoder does not function correctly enough times, the TCCM stores a motor/encoder failure DTC 2.

Diagnostic Trouble Code (DTC) 3
The TCCM performs a test each time the electronic-shift motor is turned ON or OFF. If the motor does not function properly the TCCM stores a motor circuit failure DTC 3, and the shift select buttons blink in order to inform the driver of a problem.

Diagnostic Trouble Code (DTC) 4
Each time the ignition is turned ON the TCCM tests the memory, the program, and the internal system in order to ensure that the TCCM is operating properly. If the TCCM detects a fault within the TCCM, the TCCM stores a RAM/ROM memory failure (DTC) 4.

When the TCCM is running a diagnostic, and a code 4 is displayed by the shift select buttons, replace the TCCM.

Instructions borrowed from I forget who at s-series, and modified by myself

And a link to OBD II pin-out info (http://freediag.sourceforge.net/OBD_plug_pins_and_protocols.txt)

The easy checks:
-vacuum lines from the actuator under the battery
-disconnect negative battery terminal for 5 minutes and attempt to shift again. If you are successful after battery disconnection encoder position motor is likely the culprit

Pulled this fantastic image detailing the vac lines on our engine from this post (http://www.automotiveforums.com/vbulletin/showthread.php?t=350903)

http://img150.exs.cx/img150/3230/vacuumdiagram4dx.jpg

The easy checks:
-vacuum lines from the actuator under the battery
-disconnect negative battery terminal for 5 minutes and attempt to shift again. If you are successful after battery disconnection encoder position motor is likely the culprit

Pulled this fantastic image detailing the vac lines on our engine from this post (http://www.automotiveforums.com/vbulletin/showthread.php?t=350903)

http://img150.exs.cx/img150/3230/vacuumdiagram4dx.jpg
well i'v narrowed it down to the front wheels hearing some clunking could it be a hub

PLEASE tell me, where did you get your blow up pictures?

I linked it just above the pic Blazer SS.

well i'v narrowed it down to the front wheels hearing some clunking could it be a hub

Dunno. Did you check the trouble codes? You said the SES light came on so there's something there... By "clunking" do you mean it's engaging? Check your fronts to see if they have drive. I don't know that this could be the case, but it may be possible that you just have a broken switch. Need some more info though bro.

I linked it just above the pic Blazer SS.



Dunno. Did you check the trouble codes? You said the SES light came on so there's something there... By "clunking" do you mean it's engaging? Check your fronts to see if they have drive. I don't know that this could be the case, but it may be possible that you just have a broken switch. Need some more info though bro.
Well..when I hit the switch I hear the selinoid moving so that part of hi seems to be working, when i have it in 4x4 and i'm driving i hear some clunking but when i turn sharp i can tell its not engaged. sometime it seens like it is so im thinking it may be going in and out.
thank you for all this help
Joe

Could just be partially engaging then... pull the codes and then try resetting the encoder motor. Let us know what you find, I'd really like to know what solved your problem.

Could just be partially engaging then... pull the codes and then try resetting the encoder motor. Let us know what you find, I'd really like to know what solved your problem.
Ok thanks alot..I no its engaging because i went under the truck and switched back an forth betwwen 4wd and when it was out of 4wd the front drive shaft will turn and when it was engaged it would not turn

I've had 3 of these trucks and 2 of them lost the 4wd because of a rotted vac line. Check the vac lines first. In both my cases it was the line that runs from the actuator under the battery behind the distributor (line #36 in the diagram posted by cailen). Both times it was cracked where it hooks in behind the distributor. Hope this helps. :2cents:

I replaced the whole vacuum set up with a PosiLock actuator on my '91. This neat little device lets me manually engage the front axle, now I KNOW for certain that I have 4x4 when I want it. If I don't engage the front axle then my transfer case can give me 2 low when I need it. About $140 at my local 4 Wheel Parts outlet, and about 2 hours installation.

Just to make things less confusing, those pics are for a 1994 and older engine and not the 1995. My vacuum lines are not exactly like that on my 1995.

I've had 3 of these trucks and 2 of them lost the 4wd because of a rotted vac line. Check the vac lines first. In both my cases it was the line that runs from the actuator under the battery behind the distributor (line #36 in the diagram posted by cailen). Both times it was cracked where it hooks in behind the distributor. Hope this helps. :2cents:
Ok thanks alot, i've narrowed it down to that i thought the actuator might have some corossion on it but it looks like that aint the case.

i'll try the vacume lines next, problem is you have to put everything back together to test it lol. anyway thanks for the info.
Joe
btw....NICE CAR

I've had 3 of these trucks and 2 of them lost the 4wd because of a rotted vac line. Check the vac lines first. In both my cases it was the line that runs from the actuator under the battery behind the distributor (line #36 in the diagram posted by cailen). Both times it was cracked where it hooks in behind the distributor. Hope this helps. :2cents:
Ok I've discoed tghe vacume line ai the accuater and checked for vacum coming out of the line when i engage 4wd, there is very little vacum at the line do you think its cracked or the check valve at the transfer case the culprit. the parts store told me they also go bad alot.
How strong should the vacum be?
joe

Cracked, pinched, blocked. How is the fitting at the other end? You could try blowing it out with compressed air.

I've had 3 of these trucks and 2 of them lost the 4wd because of a rotted vac line. Check the vac lines first. In both my cases it was the line that runs from the actuator under the battery behind the distributor (line #36 in the diagram posted by cailen). Both times it was cracked where it hooks in behind the distributor. Hope this helps. :2cents:
ok i dicoed the vacum line from the accuator and there is very little vacum coming from it, how strong should it be?
the parts guy told me it might be the check valve on the transfer case he sid they go bad all the time
joe

Just to clarify, you mean the actuator by the battery yes? I don't have my Haynes and searching other posts hasn't yielded information on vacuum strength, so hopefully someone else can post that.

And I think your mechanic is talking about the vac switch on the Tcase. Yes, these are prone to failure, as they get sticky fairly easily. They are an inexpensive part (~$15)

Ok thanks alot, i've narrowed it down to that i thought the actuator might have some corossion on it but it looks like that aint the case.

i'll try the vacume lines next, problem is you have to put everything back together to test it lol. anyway thanks for the info.
Joe
btw....NICE CAR
ok i tested the accuater and its seems to be working fine, when i engage 4wd its not pulling the cable all the way if i push it 1/4 of an inch or so i have 4wd could it be the accuator or something else
Joe

I just fixed the vac line on my 2000 last week. When I would push the 4hi button, I would hear the relay clicking and even the transfer case sounded like it was engaging the 4wd. The 4hi light would just keep flashing though and I'd have no 4wd. After a few weeks of randomly trying the 4hi I would still hear the relay but no sound from under the truck like it was engaging. When I checked the vac lines, the one that goes behind the distributor to the piece mounted on the firewall was off. One part of the line was still attached to the piece on the firewall. I figure it was cracked at first, that it why it sounded like it was trying to engage (prob just not enough vac to fully engage it). Than when the line totally split off, that it why I didn't hear it trying to engage anymore only the relay clicking. If yours is doing the same, I would definately check those vac lines. My last 2 blazers had that same vac line break in the same spot. And my first blazer had the sticking vac switch in the transfer case. It would usually stick in 4wd though. I used to have to pull the vac line off the actuator until I had the time to replace the vac switch. I would replace it usually every winter. Those are the only problems I've had with the 4wd on the 3 blazers I've owned.

I just fixed the vac line on my 2000 last week. When I would push the 4hi button, I would hear the relay clicking and even the transfer case sounded like it was engaging the 4wd. The 4hi light would just keep flashing though and I'd have no 4wd. After a few weeks of randomly trying the 4hi I would still hear the relay but no sound from under the truck like it was engaging. When I checked the vac lines, the one that goes behind the distributor to the piece mounted on the firewall was off. One part of the line was still attached to the piece on the firewall. I figure it was cracked at first, that it why it sounded like it was trying to engage (prob just not enough vac to fully engage it). Than when the line totally split off, that it why I didn't hear it trying to engage anymore only the relay clicking. If yours is doing the same, I would definately check those vac lines. My last 2 blazers had that same vac line break in the same spot. And my first blazer had the sticking vac switch in the transfer case. It would usually stick in 4wd though. I used to have to pull the vac line off the actuator until I had the time to replace the vac switch. I would replace it usually every winter. Those are the only problems I've had with the 4wd on the 3 blazers I've owned.
ok thanks but my line goes rite to the tranfer case there is vacume but don't no if its strong enough, honestly thats wut i think cause if if move the accuator 1/4 inch it works

Ok thanks alot, i've narrowed it down to that i thought the actuator might have some corossion on it but it looks like that aint the case.

i'll try the vacume lines next, problem is you have to put everything back together to test it lol. anyway thanks for the info.
Joe
btw....NICE CAR
Ok just wanted to tell you guys that i was traceing vacume lines and came across 1 that was discoed by the master cylender on the firewall found out where it connected to and im back in buisness, ide like to thank you all for the help
Joe