Computer Diagnostics and Tuning Technical discussion on diagnostics and programming of the F-body computers

How to test PCM?

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Old Nov 12, 2003 | 06:50 AM
  #1  
67chevy's Avatar
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How to test PCM?

I have a no start condition on a 95 LT1/A4 and through some reading and troubleshooting determined either a bad opti or bad PCM. So I have two questions:

1. How can I test the PCM? If I get a sucessful read using pcmread will that mean it's good?

2. I have a good PCM from a 94 LT1/A4. Can I swap them out, are they compatible?

Thanks in advance for the help!

Bruce
Old Nov 15, 2003 | 05:01 AM
  #2  
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Re: How to test PCM?

Originally posted by 67chevy
I have a no start condition on a 95 LT1/A4 and through some reading and troubleshooting determined either a bad opti or bad PCM. So I have two questions:

1. How can I test the PCM? If I get a sucessful read using pcmread will that mean it's good?

2. I have a good PCM from a 94 LT1/A4. Can I swap them out, are they compatible?

Thanks in advance for the help!

Bruce
Yea you can swap with another car.. Doesn't matter if it's a different tranny or not, the car will still start...

Check to see if your SES light come's on when you put the car to run.. If it does your ECM should be fine... Also check to see if your security light is on.. I bet it's your VATS system
Old Nov 17, 2003 | 01:09 PM
  #3  
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Thanks for the reply!

Yeah the SES light comes on when I turn the switch on and the security comes on also but goes off after about 5 seconds.

I swapped the PCM out but still no cranky. I'm still not getting any spark at the coil or plugs.

If I buy one of those VATS bypass modules will that fix a VATS issue? I thought the VATS controls the starter and fuel pump?

Oh well, I'll keep troubleshooting.
Old Nov 17, 2003 | 01:25 PM
  #4  
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If you are not geting any spark from the coil then you have an opti problem or the wiring harness to the opti is corroded. If you are getting spark from the coil then you definately have an opti prob. I think you should check the wiring harness to see if it is corroded. If so replace the opti.

Good Luck
Matt
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