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I have an Xjr-99 with electrical issues. It shows suspension fault message all the time but there are also problems that comes and goes like the lights, electric windows and radio sometimes not works. I have a new battery and generator. I have checked the fuses, relays , ground points and ground straps.
I have read the fault codes and it shows 9 fault with the body processor module, I bought a used module and changed it with no difference. I have not measured any wires, don't know how to do that, I'm not exactly an electric expert. Any advice what I can do next ?
The 3 items that you are having trouble with are all turned on with the same ACC (Accessory) circuit that comes from the Ignition switch. This is a Red/white wire that comes from the ignition switch and feeds ground to the BCM (Body Control Module) when the key is turned forward. Without the BCM seeing this input the windows, radio and several lights may not work. When the concern is present the best test would be to monitor the wire and see if ground is present at the BCM connector FC15 pin 41. The BCM is located behind the glove box and has a 104 pin connector that is bolted to it. It is held in with 3 bolts.
This however may not be the easiest thing to do if the concern is intermittent. An easier test to try is, when the concern occurs, get out of the car and shut all of the doors then insert the key into the drivers door lock and hold it in the unlock position and all the windows will roll down. If the windows roll down with the key in the door (or up if you hold lock) then the drivers door module and SCP is working correctly but the BCM is not seeing the Ignition switch input. You can find wiring diagrams to assist you by searching the web for XJ series electrical guide. If you can verify that the windows work using the key method, I would run a new wire from the ignition switch to the BCM. Let me know what you find and if you need more help!
Pin 1 is the Red / White wire to the BPM on page 37
Moisture gets in the switch connector so you just drop the lower column cover to get at it:
The pin 5 is a to the car frame ground and I found mine corroded
The BPM software has to match the master software of the whole vehicle so I would suggest putting the original back in when trying the ignition switch cleanup
Last edited by Lady Penelope; Aug 12, 2019 at 07:54 PM.
I bought a new ignition switch and I've also checked all cables that goes from the ignition switch to the body processor module and one cable that goes to the bulkhead. No improvement. Know also nothing happens when I try to start the car.
The Battery works fine and is fully charged. I've measured different positive/negative points all over the car and they show the same as the battery. Now when I turn on the ignition a light over the backseat turns on but nothing happens in the gauge cluster but the electric windows, radio and the seats works. Must be some grounding problem somewhere but any advice where I should look ?
The ground strap from the battery to the chassis sometimes has a poor connection in the fittings, and the bell housing to chassis ground strap should be removed and cleaned.
Electrical issues
