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Discussion Starter #21
Also wanted to ask, is there a way to verify that the PCM is functioning normal and I just don't have a bad PCM and should replace it?
 

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Discussion Starter #22
So followed Gladiators list of troubleshooting tips and GPR wiring checked out just fine. So back to square one. So while sitting in the vehicle pondering how hard it would be to pull this truck up a large hill with a cliff and push it off I decided to continue down the path of something not right with the fuse box. So I happened to unplug the heater/AC fuse and when I left the key on for about 10 seconds and then turned the key off and tried it again, the glow plugs went into a full cycle. WOW, what just happened. I turned the motor over but no fire. But all of a sudden I have glow plug cycle. So I proceed to bleed the air form the system since it's been sitting for a while and after about 10 minutes, the truck fired up and ran like a dream. Then after running for about 3 or 4 minutes, it shut off just like you turned the key off. Glow plug cycle gone again. So I put heater/AC fuse back in fuse box and turned key on. Glow plugs flickered so I left the key on for about 15 seconds. Turned off and then back on and had full glow plug cycle again. Truck started right up. This time it ran for about 8 minutes and shut off again. This time it started right back up and ran for about another 5 to 6 minutes and then shut off. So my thought went to bad PMD box. So replaced it with a new one I had bought a while ago. Same thing, truck started and ran for about 5 to 6 minutes and then shut off. The glow plugs flickered again and no cycle. I switched PMD boxes with a third one I had that I was not positive if it was good or bad. Cycled key and left on for a few seconds and then off and back on and the glow plugs cycled and truck started right up and ran for another 5 to 6 minutes and then shut off. Truck did start right back up. So what do I have going on now? Why is it running for a bit and then shuts off. Do I have three bad PMD boxes? What would make glow plugs flicker but if I leave key on with service light on for about 15 seconds, then turn key off and back on the glow plugs cycle like they should? Totally confused. Atleast it's running again so I have to be getting close to resolving this issue. Any ideas?
 

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Sounds electrical?
Any DTC?
When the engine run, does the tachometer rpm goes erratic?
 

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My next move would be to try another PCM. Did you leave the WIF and fuel heater unplugged?
99% sure it is electrical. Have you replaced the ignition switch?
Were you driving this truck before the problems or did you get it this way?
 
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Discussion Starter #25
i was driving it on a regular basis when this all started. That is why I have three PMD boxes and two GPR's. I was having intermittent stalling issues and glow plug cycle issues but I could always seem to get it to work with a little persistance and time. Seemed like switching PMD box or GPR would allow system to start working again and so I played that game for several months until that stopped working and the truck just sat until yesterday. I have plugged the WIF and fuel heater back in. I actually did that before I got the glow plug cycle to start working again. I have replaced the ignition switch last fall. Could the new ignition switch be causing this? I definitely think I have not solved my problem but am closer to the solution because I agree that it's an electrical issue. Finding that might be the toughest job of all. Here is a list of new parts that I have put on the truck since I started this. This may help and it may not but I thought I would include it anyway. New install is OPS, both Temp sensors, GPR, glow plugs. glow plug wire harness, lift pump, ignition switch, batteries, starter, cleaned all ground connections three times, PMD. I think that's it. Hopefully we are on the right track and we can find the issue. If you think of anything else, let me know. I will try another new PMD box and see what happens.

To answer JMJNet, I do have one DTC code before I got the glow plug cycle to start working. It was DTC 14, temp sensor low voltage. That is why I replaced both temp sensors on the intake and block. Have not checked codes since I did that but i will look tonight and see if there anything new. Might be a whole bunch of new ones since the truck started up.
 

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Discussion Starter #26
Forgot to mention, no the tach does not go erratic when truck is running. It runs really smooth and quiet, just like it always has. very smooth running diesel in my opinion. no knocking or banging at all. That is why I would love to get this trucking working again. Thanks.
 

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Discussion Starter #27
Ok, so we are right back where we started. Just a click of the glow plugs and no start. I checked the DTC codes and now I have several. DTC 14, 31, 42, 57,58 and 62. DTC 57 concerns me the most. PCM 5 v shortened. So that has to point to a short somewhere, right? So where do we go now? Anyone interested in buying a 1994 6.5 Diesel? I will say this that I did get the glow plugs to cycle once the way they should and it started right up. Ran for about 5 minutes and then just like you shut off the key, it quite. No more glow plug cycle after that. UGH!
 

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Post #24?
 
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Discussion Starter #29
Why I didn't catch this before but after re-reading Post #24, I see Gladiator mentions replacing the PCM again. I have heard different people reference these accronyms and mean the same thing. So Gladiator, when you say replace PCM are you talking the Power Driver Module or the actually computer module behind the glove box? Please specify. Thank you.

Also, I have a brand new ignition switch installed last fall.
 

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Why I didn't catch this before but after re-reading Post #24, I see Gladiator mentions replacing the PCM again. I have heard different people reference these accronyms and mean the same thing. So Gladiator, when you say replace PCM are you talking the Power Driver Module or the actually computer module behind the glove box? Please specify. Thank you.

Also, I have a brand new ignition switch installed last fall.
Glad is talking about the computer ( PCM ) behind the glovebox.
The PMD= Pump Mounted Driver, is what you would replace or relocate to the front bumper, that communicates IP info to the PCM
 

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PCM is the computer that controls the whole electronics in the truck.
PMD is Pump Mounted Driver controls the injection of the Injector Pump only.
 

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Discussion Starter #32
Ok so I picked up a brand new PCM but my question is if I do have a short somewhere in the electrical, won't that short knock this new PCM out when I install it or do you guys think the short is in the actual PCM? I hate to throw more money away on a new PCM if the short isn't fixed yet. I have tested and replaced just about everything on the electrical side that has been talked about in previous posts and never really located any short or broken wire. I even went through the fuse panel the best I could and never really found anything. Advice?
 

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Ok so I picked up a brand new PCM but my question is if I do have a short somewhere in the electrical, won't that short knock this new PCM out when I install it or do you guys think the short is in the actual PCM? I hate to throw more money away on a new PCM if the short isn't fixed yet. I have tested and replaced just about everything on the electrical side that has been talked about in previous posts and never really located any short or broken wire. I even went through the fuse panel the best I could and never really found anything. Advice?
Usually, it's something within the circuit board. You can inspect the wires and connector to/from the PCM carefully. Otherwise, I would just swap the EPROM over to the new PCM and then plug it into the truck
 
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