WBlanche

Hey guys, im new to forums but have read lots lately. My nobus issue began intermittently but has now become permanent. I've removed the cluster, cleaned and put dielectric grease on the plugs.Also done the 10 point test and the cluster tested ok. The CPS is okay. A mechanic tested and says he is getting a code for the PCM. In many of the threads, the PCM has been changed with no results. Is there a way to test the PCM? I plan on cleaning the 2 grounds by dip stick tomorrow. Any other suggestions certainly appreciated.

CCKen

1st: There's no point in putting dielectric grease on the instrument cluster connectors.

2nd: Find out what code the mechanic found. Need a number.

3rd: The wires at the dipstick are for the Data Link Connector and will have nothing to do with a no bus issue.

Open this link for pics of the ground points in the engine bay.

Click the image to make it larger. Click it again to make it larger yet.

https://www.cherokeeforum.com/g/album/3212734

G100 and G101 are the critical grounds (besides the battery connectors).

Your engine won't have a coil at G101 but will have the two ground studs there.

Remove the wire ring terminals from the ground points at G100 and G101 and scrub them using 400 grit sandpaper or Scotch-Brite pads. Reassembly securely.

DO NOT use dielectric grease on these grounds.

WBlanche

Thanks so much. It's raining today so will be tomorrow before i can work on the grounds. The code i was given was a 1683.

CCKen

Here's P1683, and possible causes:




P1683-SPD CTRL PWR RELAY; OR S/C 12V DRIVER CKT


When Monitored: With the ignition key on and the speed control switched on.


Set Condition: The speed control power supply circuit is either open or shorted to ground.




S/C POWER SUPPLY CIRCUIT SHORTED TO GROUND


GROUND CIRCUIT AT S/C SERVO CONNECTOR OPEN


S/C WIRING HARNESS INTERMITTENT PROBLEM (S/C VENT SOL AC)


S/C VACUUM SOLENOID CONTROL CIRCUIT OPEN


S/C VACUUM SOLENOID CONTROL CKT SHORT TO GROUND


S/C VENT SOLENOID CONTROL CIRCUIT OPEN


S/C VENT SOLENOID CONTROL CKT SHORT TO GROUND


S/C WIRING HARNESS INTERMITTENT PROBLEM (S/C VAC SOL AC)


S/C WIRING HARNESS OBSERVABLE PROBLEM


S/C SERVO (12V DRIVER CIRCUIT)


S/C SERVO (12V DRIVER CIRCUIT)


S/C POWER SUPPLY CIRCUIT OPEN


BRAKE SWITCH


BRAKE SWITCH OUT OF ADJUSTMENT


S/C BRAKE SWITCH OUTPUT CIRCUIT OPEN


S/C BRAKE SWITCH OUTPUT CIRCUIT SHORTED TO GROUND


PCM (12V DRIVER CIRCUIT)

CCKen

Update?

Rail

I think someone needs to draft a no bus diagnostic that is sticky worthy. Maybe CCKEN. Seems like every no bus thread I read through CCKEN has posted a response.

Jay Hyland

I hope you can help me CCken....

I have poured over the posts the last few weeks chasing a "no bus" issues. I cleaned the cluster contacts 4 times. I replace the CPS. I tightened the grounds at the engine strap (it was loose) and looked over all the other grounds indicated another poster.The vehicle will start and run and no more than 5 minutes into a trip the air bag will illuminate, then the gauges will die (first the tach and speedometer) then the airbag light, followed by the check engine light and finally the "no bus" indication.

I am convinced it is a ground issue but if it is not the grounds you indicated, where should I look?

CCKen

With a CHECK ENGINE light you should have diagnostic trouble (DTC) code(s) stored in the PCM/TCM. Have the codes read at an auto parts store and post the DTC numbers here.

Jay Hyland

will do....

Jay Hyland

OK... Pursuant to your directive this morning I went to the parts store and they hooked it up. There were no codes... but, the check engine light was not on either. So I drove it a bit until the "no bus" issue (along with the check engine, air bag and dead gauges) occurred again. I just came back and there was still no codes present even with the aforementioned indicator(s) errors present.

The clerk suggested the codes may only be present but only accessible with a dealer only scan.

Also, I want to clarify a bit on the earlier post relevant to "checking the grounds" What I did was put a hand on the terminals (battery negative to the body, firewall from the back bolt and the two on the side of the engine by the oil filter) to see if there was play. There was play on the braided ground strap at the back of the engine and I tightened that. I could not find the ground under the dash on the left side above the hood release latch.

I did take a video of all of the scan tool comm data that was being read if it is of any help.

CCKen

You may have pending codes that the parts store guy didn't look for or the parts store code reader was not set to Jeep parameters.


In any case, you should disassemble each ground point in the engine bay and clean each wire ring terminal using a wire brush or 400 grit sandpaper and securely reassemble each ground. Do not use Dielectric grease at any ground connection.


Why are you looking for a ground under the dash?


If you can post your video it may help.

CCKen

I guess I missed something....what year is your XJ? By the looks of it it's an OBD II XJ, but let us know what year it is.

Jay Hyland

I read in one of the posts that there is a ground under that dash that controls the dash light and cluster inter alia. I understood that ground to be more relevant to my concern than the engine compartment grounds.

I am working on figuring our how to upload the video

Jay Hyland

It is a 2001 Cherokee. Some of the posts I read were for older Cherokees so I was wondering if this ground even exists on my Cherokee

CCKen

There are two grounds under the dash, left side and right side. But they rarely go bad - unless someone has messed with them.