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Unknown ground plug

Craigesmith52

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May 20, 2021
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32931
In the ongoing pursuit to someday get my gauges working in my 1999TJ I found this plug not seeming to have a home. Located on the drivers side

image.jpg
 
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Craigesmith52

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I guess it could be as I do not have cruise control on the vehicle so that would be why it is unplugged. Thanks for the replies
 
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Craigesmith52

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May 20, 2021
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Well just as an update I checked my PCM voltages and I am not getting any reference voltage on the Black PCM on pin 17 or on the White PCM on pin 31. I do get voltage readings on 2 & 22 on the Black PCM and clean ground readings on lines 31 & 32. Looks like it is time fore a new PCM board.
 

Steve04

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Jan 21, 2022
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North Carolina
Does the Jeep start and run? Runs but gauges don’t work? If the diagram I found online is accurate the wires you say you checked are the reference voltage to most sensors. Gauges work off the ccd + and ccd- wires in the grey connector
 
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Craigesmith52

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May 20, 2021
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Jeep runs just fine and the idiot lights work (gas is low, brakes on, etc) but none of the gauges that show how full the gas tanks is, oil pressure, water temperature, etc show anything at all. I had seen a post in the forum which indicated the testing of the pins I did.
Does the Jeep start and run? Runs but gauges don’t work? If the diagram I found online is accurate the wires you say you checked are the reference voltage to most sensors. Gauges work off the ccd + and ccd- wires in the grey connector
This is what I was referring to reading on the other forum
Hi, just found out about an easy way to test your PCM if you suspect its junk.
1-Verify that there is battery voltage going in to the PCM at pin connectors 2 and 22 on the black connector. These are the orange wire and the red/yellow wire.

2-Verify that the 2 ground wires for the PCM are reading 0 resistance/good continuity to ground. These are the 2 black/tan wires at pins 31 and 32 in the black connector.

3-Test for reference voltage (5v) coming out of the PCM at pin 17 ( orange wire) at the black connector and pin 31 (violet/orange wire) at the white connector.
If the power input leads and grounds are good, but nothing is coming out of the two reference leads, then the PCM is smoked. Period. Don't bother to test sensors, wires, relays, etc. Thats it!!!:atomic::rip:
 

Steve04

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Jan 21, 2022
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Location
North Carolina
The 5v reference wire supplies voltage for the cam/crank, tps and map sensor so that must be working or it would not run. The cluster works off the bus system and the odometer would be reading “no bus” if it wasn’t working. I think your next checks need to be to verify cluster has power and ground
 

Steve04

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Joined
Jan 21, 2022
Messages
28
Location
North Carolina
Also this forum has at least one thread about connections in back of the cluster being suspect. The connectors are clipped to the dash structure and the cluster slips into them and sometimes causing poor connections