2nd Gen Non-Engine/Transmission Not the CPS, now what?

[ejtaintor]

Alright, I am trying to fix a few things on my old man's '95 1 ton 5 speed. The one I'm working on has me stumped. The tach and speedo stopped working, the alternator appears to not be fielding so it's not charging, and the air bag light is staying on.



I've heard this could be the CPS but I heard if it's bad, the WTS light won't come on. This one is coming on. My dad had picked up a new Cummins CPS so I threw it on and gapped it to . 049 with non-metallic guages.



Fired the truck and no change.



I've heard that if metallic feeler guages are used, it can ruin the CPS. When I pulled the new CPS out of the box, one of the wire clamps was stuck to the actual sensor (magnetically). Could this have ruined the part before I even had the chance to swap them?



Next I've heard the problem could be the PCM. I'm really hoping this is not the case but what should I be checking to diagnose?



Any other things to take a look @?





BTW, I had seen the other post regarding this but I'm a bit further along and looking for "what now?"

 

[Dave M]

Here is a thread I had when my ESS was bad:



https://www.turbodieselregister.com...ons/184945-electrical-woes-maybe-bad-pcm.html



It sounds like its:



1. ESS

2. connections at PCM or ESS

3. PCM



PCM's usually don't go bad but they can. They run 200-300 dollars on ebay and $500 at dealer.



Unplug you batteries (both) GND's before working on PCM. Unplug those 3 connectors and verify they are good as far as pins ok, no corrosion etc. I'd get a schematic and verify voltages and gnds at the PCM it you can but be carefull not to fry your PCM by testing and shorting something. If the ESS is not bad then the PCM is suspect.



Try measuring the voltage coming from PCM to the ESS at the ESS 3 pin connector. One pin is GND (verify the GND is good by put voltmeter +lead on battery and voltmeter neg lead here at this GND... its good if voltmeter reads 12vdc), one pin is a voltage like 5 vdc (some PCM voltages here are different like 8 vdc... mine was 5vdc... . that is supplied from the PCM and the other pin is the output pulses from the ESS to the PCM (probably can't be measured with Voltmeter but you can't hurt it trying). Try unplugging the ESS and measure for 5vdc and with ESS plugged in measure the PCM voltage here again. Mine was 0 vdc with ESS connected and 5 VDC with ESS disconnected..... my bad ESS was shorting out the PCM voltage to the ESS. A new ESS cured my problem and the old PCM was still good.



Verify all fuses at PDC and dash fuse panel are good. Look for bad gnd's and voltages and connections. These problems can be tough to diagnose.



Good Luck,

Dave