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Hello fellow Dodge truck enthusiasts. I have a 1997 Ram 2500 4x4 Ext/Cab diesel automatic. I have in the last few weeks encountered a problem I haven't been able to fix. Its been in the shop costing me thousands and I don't know if I should scrap the truck. Its in such great shape. I just had it repainted 3 weeks ago. After parking the truck from a normal days paved highway use. Start truck: No tach, speedo, manifold heater, water in fuel light, charging, cruise control, overdrive or transmission shift, air conditioning. Shop has replaced PCM, wiring plugs connected to PCM, and spent dozens of hours trying to find the problem. I am running out of hope and money...

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Did you blow the FL or did you misplace it? If it blew then id say for sure it is a harness issue. Ive seen only a handful in my life and every one was a harness issue, short to ground or back-fed circuit. Now that I think about it if the Dodge computer is good or new there is not much else for electronics on the truck since its a 12V.

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Hello fellow Dodge truck enthusiasts. I have a 1997 Ram 2500 4x4 Ext/Cab diesel automatic. I have in the last few weeks encountered a problem I haven't been able to fix. Its been in the shop costing me thousands and I don't know if I should scrap the truck. Its in such great shape. I just had it repainted 3 weeks ago. After parking the truck from a normal days paved highway use. Start truck: No tach, speedo, manifold heater, water in fuel light, charging, cruise control, overdrive or transmission shift, air conditioning. Shop has replaced PCM, wiring plugs connected to PCM, and spent dozens of hours trying to find the problem. I am running out of hope and money...

Ahh... Are you sure its the PCM (Powertrain Control module)? Because the PCM doesn't control most of that stuff the the only thing it controls alternator. The ECM (Engine Control Module) on the side of the engine controls most all those devices.

Sound more like a CCD Bus/Network error.

http://articles.mopar1973man.com/general-cummins/34-engine-system/81-ccd-data-bus

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What you need to do is take a DVM and check for the bus voltage. You can probe pins 3 and 11 in the OBD socket and reference to ground. So what I mean is if you insert the red probe in the #3 pin the black probe will be in #4.

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So what I would do is probe the socket looking for the voltages shown most likely be shorted to ground (0 VDC) so I would continue to unplug devices. ABS brakes, Air Bag controller, Radio, Instrument cluster, overhead computer (if equipped), etc.When the signal returns then you know you've found the issue. I would also check for error code because it might clue in on which device that might of failed.

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Have you gone through with a multimeter to make sure power is getting to each fuse? The PCM is turned on with the key switch and it can go bad and you would see that with no power at the fuse. Make sure and check both sides of the fuse, you should be able to just stick the multimeter probes on the tops of the fuses. Mike had a fuse blow that didn't look blown but was broke somewhere you couldn't see or something so thats why I say probe both sides. I assume you have a wiring diagram? If you have power going through all the fuses when the ignition is on like they all should, I would get a needle and start piercing wires to see if the ignition and grounds for the PCM are actually working correctly. The grounds are pretty crappy on these things. But it's definitely an issue of the PCM not doing anything. If all else fails, bring it to me and I'll fix it for free. Would love to have a PITA issue like this :hyper:THIS IS A 12V MIKE!!! lol no ECM.

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Tested all the fuses, fusible links and grounds. Checked all wires from pcm for continuity through harness to dash behind cluster as well. I have removed the alternator for testing tomorrow morning. Dodge dealer says faulty alt can burn out a pcm. They believe the replacement pcm was burnt out when it was installed by a possible failing or faulty Alt. I am having a hard time with this problem but I am persevering...

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This might be a little late to bring this up... could a crankshaft position sensor cause all these problems at the same time. If the crankshaft sensor was faulty could it trick the pcm into thinking the truck was not running. No a/c, cruise, tach, speedo, trans overdrive or shift, wait to start light, temp gauge... just thinking out loud.

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Tested all the fuses, fusible links and grounds. Checked all wires from pcm for continuity through harness to dash behind cluster as well. I have removed the alternator for testing tomorrow morning. Dodge dealer says faulty alt can burn out a pcm. They believe the replacement pcm was burnt out when it was installed by a possible failing or faulty Alt. I am having a hard time with this problem but I am persevering...

- - - Updated - - -

This might be a little late to bring this up... could a crankshaft position sensor cause all these problems at the same time. If the crankshaft sensor was faulty could it trick the pcm into thinking the truck was not running. No a/c, cruise, tach, speedo, trans overdrive or shift, wait to start light, temp gauge... just thinking out loud.

load test the alternator. but even a bad alternator should still allow you to jump start the motor, If you can get the engine to run then you know its an electrical issue.

im wondering if the thing even crank, are you sure its not a battery issue, my dakota had a shot battery, held 12v but when you went to crank nothing worked, the thing couldn't even get the starter to run. and yea gauges all died.

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load test the alternator. but even a bad alternator should still allow you to jump start the motor, If you can get the engine to run then you know its an electrical issue. im wondering if the thing even crank, are you sure its not a battery issue, my dakota had a shot battery, held 12v but when you went to crank nothing worked, the thing couldn't even get the starter to run. and yea gauges all died.

Yes the engine starts and the truck can be driven. Nothing pcm related operates.
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This might be a little late to bring this up... could a crankshaft position sensor cause all these problems at the same time. If the crankshaft sensor was faulty could it trick the pcm into thinking the truck was not running. No a/c, cruise, tach, speedo, trans overdrive or shift, wait to start light, temp gauge... just thinking out loud.

Definitely for most of it, BUT, the WTS should come on before you even try to start the truck. It still sounds like you do not have power getting to the PCM.
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Well. The truck is fixed. This I can say for certain. The crankshaft position sensor sends a signal to the PCM to let the PCM know the engine is running. The PCM does not operate without the 5 amp signal from the crankshaft position sensor. The list of inoperative features include all of these: No tach, No speedometer, No charging system, No overdrive lock out, No auto trans shifting, No manual shift into 1st gear, No wait to start light, No water in fuel light, No cruise control, No air conditioning. Installed a new cps and everything worked immediately. Anyone need a PCM I have a spare. The dealer is making a large adjustment to the bill. I replaced the cps on my own out of frustration. All is well again. Thank you all for your suggestions and help with this problem. Hopefully someone else can benefit from this information in the future. CHEERS...

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