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Well, still stuck after a new optical sensor change. NO CHANGE AT ALL. Starts ok after 5-10 sec of cranking and instantly get check engine light with codes 17,18, 35,36... Any new suggestions? I have a OBD1 cable and working on getting a laptop to put the software on. Are there other grounds that I'm not aware of? 3 on the back of the passenger side head, 2 battery grounds and one under the exhaust manifold on the passenger side? Could the PCM be bad? Any help is greatly appreciated...
To test the PCM disconnect the batteries for 30 minutes to clear all codes then reconnect.
Insert IGN key and turn the key to the ON position but do not start the vehicle.
Now check for any codes.
If any codes appear and the vehicle is not started, the PCM is bad.
 

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Discussion Starter #22
Awesome - I'll try it after work!
 

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Discussion Starter #23
Ok - I got code 12 - which I believe is a normal code. Any other ideas?
 

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1995 GMC Suburban
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Did you ever test with another KNOWN WORKING PMD?

I know you did not test the LP but you need to regardless because on a 95, the LP is run by the OPS when engine is running.
So if the part of OPS that controls the LP is bad or intermittent, the LP will NOT run.
If the LP is running, you may need to determine the fuel pressure.

If all of these are good, then, the Injector Pump may be bad.
 

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Ok - I got code 12 - which I believe is a normal code. Any other ideas?
In post #3, member jnlperformance posted a diagnostics and DTC procedures manual in.pdf for you to download to your computer.
Look through that and follow the diagnostic procedures for each code that pops up .
 

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Discussion Starter #26
I did the lift pump test a while back and it tested good. I did run through Diagnostic test for code 17 and 18 and one came up bad optical and the other was bad PCM. I'll be hooking up a scanner shortly. The PMD I bought a kit off ebay with an extension harness and grey standyne pcm driver. Both new. Maybe the pmd is defective?
 

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I did the lift pump test a while back and it tested good. I did run through Diagnostic test for code 17 and 18 and one came up bad optical and the other was bad PCM. I'll be hooking up a scanner shortly. The PMD I bought a kit off ebay with an extension harness and grey standyne pcm driver. Both new. Maybe the pmd is defective?
Who was the eBay seller that sold you the PMD relocation kit?
 

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1995 GMC Suburban
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You have to test EVERYTHING when symptom(s) show up.
All the test you did before the symptoms were invalid.

Just to tell experience reading in this forum.
There was somebody who got to change everything including IP.
Only to find out that one of the battery were bad.

Also, new parts do not mean that they are good.
Anyway, it is up to you.
 

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Discussion Starter #29

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This is the ebay auction I bought the PMD and extension harness:

https://www.ebay.com/itm/NEW-GM-6-5-TURBO-DIESEL-STANADYNE-PMD-FSD-MODULE-COOLER-KIT-COMPLETE-54/133046497939?hash=item1efa307293:g:r08AAMXQ9u1REli2

I guess at this point I'll start over again and start with the grounds....
Here is the link for grounds:
https://www.dieselplace.com/forum/showthread.php?t=163087

Go through each one, remove and clean then reinstall.
Replace any that are in questionable shape.

There is also a small ground wire to the PMD located on top of the IP secured with a torx screw. Make sure that is intact
 

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Discussion Starter #31
Well I gave up. I dropped off the truck at Precision Diesel this week for them to have a go at it. Thank you all for your help and if anyone is interested in the results I will post them when I find out the issue.
 
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