1998 PCM Swap

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Mrich0908

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No joy. I installed a different PCM from a 99 tahoe and stepped through the procedure twice. Both times the security light turned off, but the truck wouldn't start afterward. Is there anything else I might be missing?

Is it starting at all . If it was vats the truck would start normal run for 4-5 seconds and die . Then it shuts down for 10 mins not allowing it to start again till the 10 mins is up.
If this is the case you may have to send it off and have vats disabled or reprogram your key for that ecm. Ive never had this problem. SO im not sure how to help you.
 

V_Kint

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Is it starting at all . If it was vats the truck would start normal run for 4-5 seconds and die . Then it shuts down for 10 mins not allowing it to start again till the 10 mins is up.
If this is the case you may have to send it off and have vats disabled or reprogram your key for that ecm. Ive never had this problem. SO im not sure how to help you.
On the first try the truck ran for a few seconds and died. I waited for the security light to go off, turned of the key, waited a few seconds, and tried to start again. It now coughs to life and dies within a second. I've tried the procedure twice now.
 

mattillac

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I have to wonder what the status of your SECURITY light was after you performed the relearn proceedure(if it was done correctly), was the light illuminated, flashing or extinguished ?

On the first try the truck ran for a few seconds and died. I waited for the security light to go off, turned of the key, waited a few seconds, and tried to start again. It now coughs to life and dies within a second. I've tried the procedure twice now.

To me it sounds like you have not performed the entire "30 minute" relearn proceedure.

It should take thirty minutes to perform the task.

Can we confirm that you have completed the entire process. Your post should have looked more like this below, no?

First ten minutes....

.....first try the truck ran for a few seconds and died. I waited for the security light to go off, turned of the key, waited a few seconds, and tried to start again. It now coughs to life and dies....

Second ten minutes....

....waited for the security light to go off, turned of the key, waited a few seconds, and tried to start again. It now coughs to life and dies....

The third ten minutes.....

...waited for the security light to go off, turned of the key, waited a few seconds, and tried to start again.......

So in total, it takes four cycles/rotations of the ingnition key to the start position to complete the relearn.

Off to Start, waited for light to go out,
Off to Start, waited for light to go out,
Off to Start, waited for light to go out,
Off to Start, relearn complete

FWIW, we only need to bump the starter(so to speak)during the relearn, no need to actually start and stall the engine, I pulled either the fuel pump relay or the starter relay when I was doing a relearn on my 99.

Food for thought, best of luck.
 
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mattillac

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Ya that would be your vats huh .
This document below may help may not. I also did a crank relearn procedure before I tried starting it. Its similar to this but little different .
GM Document ID 835015 helps you with this one.

You must perform a theft relearn procedure if any of the following components have been changed.

PASSLOCK TM

BODY CONTROL MODULE

POWERTRAIN CONTROL MODULE

The above modules, with the exception for the PASSLOCK Sensor must also be programmed with each module's own vehicle configuration. See the individual module service manual section.

Auto Learn:

Time required, approximately 10 minutes

1. Insure that the battery is fully charged.
2. Use the.........

That info seems to be for a 1998 Chevy Malibu, probably from http://www.bobstractorpartscorner.com/passlockrepair.htm ?

To the best of my knowledge, passlock on a GMT400 generally requires a 30 minute proceedure............

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

PASSLOCK REPROGRAMMING AUTO LEARN

IMPORTANT: If a new vehicle/powertrain control module (VCM/PCM) is being installed for the first the manufacturing enable bit will be set and the auto learn procedure may not be necessary.

The following procedure allows for anyone to reprogram the EVO/PASSLOCK module learned data code with any tools, other than the scan tool, when any of the following parts are replaced:

The EVO/PASSLOCK module
The PASSLOCK sensor
The VCM/PCM

The EVO/PASSLOCK module will set the DTC B3031 in the learn mode when entering the reprogramming procedure.

IMPORTANT: Erase the PASSLOCK related Diagnostic Trouble Codes (DTCs) that are stored in the VCM/PCM.

The following is the Auto Learn Procedure:

1. Insure the ignition key is in the ON position.
2. Clear all EVO/PASSLOCK module and VCM/PCM DTCs.
3. Momentarily rotate the ignition key to the CRANK position (Do NOT start the vehicle), then release it to the RUN position (Do NOT key OFF in the process).
4. Wait 10 minutes . Observe the SECURITY indicator. Refer to the following list for the appropriate responses:

-If the PASSLOCK sensor was replaced the SECURITY indicator will flash for the 10 minutes duration.
-If the EVO/PASSLOCK module was replaced, the SECURITY indicator will flash for a few seconds and then remain ON for the remainder of the 10 minutes duration.
-If the VCM/PCM was replaced with a new programmed VCM/PCM and connected to the vehicle for the first time, the vehicle will start and this procedure may not be necessary.
-If the replacement VCM/PCM was connected to any vehicle at any other time, even momentarily, the SECURITY indicator will flash for a few seconds and then remain ON for the 10 minutes duration.

5. The SECURITY indicator will transition from flashing to ON briefly to OFF after 10 minutes if remaining in the ignition ON position.
6. Turn the ignition switch to the OFF position and wait for 10 seconds .
7. Repeat steps 3-6 two more times. The new security code is ready to be communicated among the PASSLOCK sensor, EVO/PASSLOCK module and VCM/PCM. The new password is learned on the next ignition lock cylinder cycle from OFF to CRANK to ON (start attempt).

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

I should have been more clear in post number 4, my apologies.
 
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V_Kint

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That info seems to be for a 1998 Chevy Malibu, probably from http://www.bobstractorpartscorner.com/passlockrepair.htm ?

To the best of my knowledge, passlock on a GMT400 generally requires a 30 minute proceedure............

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

PASSLOCK REPROGRAMMING AUTO LEARN

IMPORTANT: If a new vehicle/powertrain control module (VCM/PCM) is being installed for the first the manufacturing enable bit will be set and the auto learn procedure may not be necessary.

The following procedure allows for anyone to reprogram the EVO/PASSLOCK module learned data code with any tools, other than the scan tool, when any of the following parts are replaced:

The EVO/PASSLOCK module
The PASSLOCK sensor
The VCM/PCM

The EVO/PASSLOCK module will set the DTC B3031 in the learn mode when entering the reprogramming procedure.

IMPORTANT: Erase the PASSLOCK related Diagnostic Trouble Codes (DTCs) that are stored in the VCM/PCM.

The following is the Auto Learn Procedure:...
7. Repeat steps 3-6 two more times.

I should have been more clear in post number 4, my apologies.

Glad to find out that it's something simple. One potential issue - I don't have a way to clear DTCs. If my CEL is off does that indicate that DTCs are clear, or are there some DTCs that that don't cause a CEL?
 

Mrich0908

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Glad to find out that it's something simple. One potential issue - I don't have a way to clear DTCs. If my CEL is off does that indicate that DTCs are clear, or are there some DTCs that that don't cause a CEL?

Im really sorry , I dont know why I had that link saved. Mattillic is 100% correct. As I stated . I did the relearn procedure and mine fired up. You defiantly have a vats problem though.
You can go to any auto part store , harbor freight and get a cheap code reader.
About 7 years ago I purchased an elm bluetooth code reader thingy . like 15$ shipped. With new software for android and windows it is as good as 800$ scanners ive seen. It works for every car Ive ever used it for . It is something I recommend to any one who works on cars. I have hptuners and still use it.
 

V_Kint

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Im really sorry , I dont know why I had that link saved. Mattillic is 100% correct. As I stated . I did the relearn procedure and mine fired up. You defiantly have a vats problem though.
You can go to any auto part store , harbor freight and get a cheap code reader.
About 7 years ago I purchased an elm bluetooth code reader thingy . like 15$ shipped. With new software for android and windows it is as good as 800$ scanners ive seen. It works for every car Ive ever used it for . It is something I recommend to any one who works on cars. I have hptuners and still use it.
I don't know that I have any DTCs to clear. I'm about to step outside and give the 30 minute procedure a shot. Hoping for a good result...
 

Mrich0908

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I don't know that I have any DTCs to clear. I'm about to step outside and give the 30 minute procedure a shot. Hoping for a good result...

You could always pull the battery for x amount of mins that will clear DTC also.
You should still buy the Elm27 dongle it really is a life long tool for 15$. I suggest any one who dosnt have one should.
 

V_Kint

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You could always pull the battery for x amount of mins that will clear DTC also.
You should still buy the Elm27 dongle it really is a life long tool for 15$. I suggest any one who dosnt have one should.
Thanks, and yep - just pulled the battery cable while I hooked up the replacement PCM. Wish me luck.
 
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