I have a 2000 Cherokee Sport 4.0 approx. 211,000 miles. Every time i am driving and have the ac, lights, or radio on the dashboard quits working. The check engine light and airbag light comes on as well. The engine also begins to rattle like it is misfiring. As soon as turn off one or a couple of the offending electronics the issue goes away. The check engine codes all seem to indicate a PCM issue.

I have recently replaced the battery and the alternator was replaced two years ago.

I was wondering if anyone has had similar issues or could possible help me with this issue. I would hate to drop hundreds of dollars on a PCM if that isn't the issue.

Thanks,

 

Before you dump hundreds into a new PCM, try a used PCM from a boneyard. Get one the same year.

 

Check your ground straps and your battery cables. Sounds to me like you have minimal ground going on and any time you are putting load on the system the electrical is fighting each other.

If I remember right there are 2 in the engine bay (one next to the battery, one at the back of the motor) and one under the dash. Someone please correct me if I missed one

 

Could you post the exact code numbers?

 

Open this link and view the pics of the engine bay grounds. Click the pic to make it larger.


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


There's one for 97/98 XJ's and G101 shown has a coil in that spot. The 00/01 won't have a coil there but the ground studs are there.

 

Good stuff. Had no idea there were that many individual ground points... into the bookmarks you go lol

 

Thank you for the responses. The codes I am getting are P1698, P0305, P0700, P1694.

 

P1694 - No CCD Messages Received From ECM/Fault in conpanion Module/Bus communication failure to PCM
P1698 - No CCD Messages received from TCM
P0305 - #5 misfire
P0700 - Transmission control system malfuctioning

I am still thinking bad grounds and all the modules are fighting for ground. Check all your ground points and slice open the side of the insolation of your battery cables close to the terminals and see if you have green crap in them. Mine looked fine from the outside until i went to replace a worn out battery terminal and when I cut the wire off the stock terminal the wire was corroded green inside

 

No.


Yes.

Don't start spending money when there is an obvious basic maintenance item that needs to be done, which might take care of the whole problem. IF's hypothesis is right on the money. Start there.

Once the FREE basic maintenance is done, if you still have a problem, it's time to start diagnosing, not part swapping.

 

I just cleaned all the grounds. It is still having the same issues. Gauges drop and check engine/airbag light comes on, when i turn on the AC.

 

Now check the integrity of your wiring, and look for corrosion. When there is corrosion in a conductor (or a connector) you can test with a voltmeter and see the correct voltage, but once a load it put on it, the voltage drops. This is why a test light is sometimes better than a voltmeter -it puts some load on the circuit. And sometimes a voltmeter is better than a test light. You really need both tools in your kit.

 

You may want to check your positive battery cables and all the points they connect to. Your battery cable branches off to the alternator, starter and fuse box so it's possible to have no charging issues yet still have problems with higher electrical loads on the system if the cable is bad where it splits off to the starter and fuse box

 

After testing the battery, alternator and ground cables, plus ground connections for the wiring harness, you might want to inspect the wiring related to the CCD bus, TCM, DLC (data link connector) and instrument cluster.

* Inspect any relevant fuses, spade type power and ground connections for corrosion. Sometimes corrosion lowers and/or interrupts power voltage or grounding effecting the CCD bus. (a faulty or weak relay possibly could be interrupting power to a device)

Possibly the P0305 DTC is related to the other DTCs.

P0305 - http://www.obd-codes.com/p0305

Link to " Code P1698 P1694 P0700 + Airbag light and Gauges on/off"
http://www.naxja.org/forum/showthread.php?t=1120141


The first thing to look at is usually power cabling, grounds & fuses then PCM related wiring and connections.

================================================== ========

P1694-CCD MESSAGE FROM JTEC FAILURE (something interrupted or blocked CCD bus communications)

______

P1698-NO BUS MESSAGE FROM TRANS CONTROL MODULE

- Faulty Engine control Module (ECM)
- Engine control Module(ECM) harness is open or shorted
- Engine control Module (ECM) cicuit poor electricl connection
- Low battery voltage


P0700-TCM DTC PRESENT (most likely set because of DTC P1698)
A DTC was registered in the Transmission Control Module.