Dear Mr. Kilmer,

I'm watching your videos regularly and thank you very much for making the content available!

I am more of an old IT veteran than car mechanic, but have also some knowledge of electronics and cars. Lived in Houston as well for some time, now in Jasper with my wife.

In 2008 I bought a Jeep WJ, model year 2001. It was running fine and I just had to repair the normal stuff. It has now about 192k miles. All running fine. I do my own maintenance. Regular oil changes, water pump replacement, this and that. I try to keep it in good shape.

Then, in July this year a lightning strike hit the electronics. It went from the bottom of the tree right into the Jeep. At the time I had also connected a flow charger to the 12V outlet. The charger is now faulty, too.

I did a lot of research and repair already:

Biggest problem with the strike: The body control module shorted when the strike hit the Jeep, and the horn, wipers and headlights came on. There was no way to switch them off. The PCI bus was not working anymore: Typical indication is AC, power windows, mirrors, etc. not working.

The instrument cluster did not show any gauge activity and all the warning gizmo lamps came on. The engine was starting, though. And it runs just fine. I just couldn't see any oil pressure on the IC, etc.

I pulled the BCM out and as assumed the connectors for horn, wipers and headlight were shorted to ground. Checked it and yes it was the case. 0 Ohms on the connector pins for the horn, wipers and headlights.

I bought an old BCM on Ebay and that problem with the headlights, horn and wipers was gone. But the PCI bus had still not enough voltage (around 0.2V, checked with a multimeter). I checked the resistance of the control modules at the PCI hub beneath the steering wheel and found out the instrument cluster had only 450 Ohms. Pulled the IC out and all seems to work fine. Beside of the door lock modules not really synchronized. I can either use the switch on the driver door to lock all doors or the remote control to lock all doors except the driver door. But that is a minor problem and not important. I checked the passenger door module resistance today and the PCI connector there has about 8200 Ohms. I checked some manuals and that is too low, but could also be okay. Because the 01 models PDMs should have 10800 and the 02 models 8200. Could be the first owner exchanged it already. I did also check the IC with the passenger door module disconnected, but it does still not show any gauge activity.

I did also check the PCM PCI Ohms and it looks fine with 3300 Ohms.

After pulling the IC out all is working fine (beside of the door lock synchronization). I can even connect a Bluetooth DRBII module and can watch the RPMs and water temp, etc. on my phone.

The only thing is it does not show any error codes.

So I bought another used IC on Ebay. It has a little less mileage with 177k. Put it in and all works fine. Just the "new" IC does still not show any gauge activity. I did also measure the PCI connector at the new IC and it shows the expected 2400 Ohms. But of course the IC which I bought on Ebay could also be faulty. How do I know that? I did the self test of the IC and it works. But that can't tell if the PCI in the IC is 100% functional.

The check engine lamp comes on after some seconds, but still no error codes. The indicator lights for high beam works fine and the other indicator lamps seem to work.

I did also check to just connect the PCM, BCM and IC via the PCI bus and leave the other modules disconnected. Still all working fine, except the IC gauges.

Here is my question (or rather questions):

  1. Does the IC need to be programmed by the Jeep DRBIII or any other expensive tool to show gauge activity like RPMs, voltage, oil pressure, fuel level and water temp?

  2. Or can every instrument cluster just be replaced with the same model without reprogramming? I checked it is the same model number.

  3. Or could it be something else - maybe even the PCM which shows the values on the DRBII Bluetooth connected phone, but not on the IC?

  4. As I switched also the BCM, of course it could theoretically also be that the bought BCM does not send values to the IC if that is needed.

I do not know how the intercommunication on the PCI bus between the PCM and IC (maybe with the BCM) exactly in detail with the Jeep firmware works. I have a portable oscilloscope though and would be able to check something simple if I know what to search for. I know it should be between 7.5V and 0V square wave. But that seems to work, because I can use all other PCI feature like switching lights on/off, wipers, mirrors, power windows, etc.

The engine is still running fine, btw. Just know that I bought a new preprogrammed PCM some years ago and did not connect the SKIM module so it is working since without the SKIM module activated/connected.

I would be very glad and thankful if you could take the time to look into my issue and answer my questions!

I wish you a very nice weekend!

Kind Regards

Gottfried

Comments (3)
No. 1-3
Cytux
Cytux

Alright, I repaired it. It was a blown resistor in the PCM. Now everything works. Cost less than a cent and no programming or dealer computer needed. Just my standard scope did the trick.

Cytux
Cytux

Thanks! Well, I'll figure it out on my own than. Swapping the BCM worked though. It's just the instrument cluster not working.

ScottyKilmer
ScottyKilmer

Editor

jeeps have garbage electronics, period. And to work on them, you really need a dealer level computer and wiring diagrams and a lot of knowledge. Swapping parts and then trying to use them without reprogramming yourself is an exercise in futility. Personally, I would never do anything but use factory oem NEW electronic parts on those.