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ramsar 09-13-2011 11:23 AM

Body control module
I have the problem with my jeep grand cherokee the gauge of the temperature doesnt move and the gas level too, also the whisper doesnt work when its raining, its suposse that its body control module is bad, and it must be replaced ( the mechanic says). there is any solution for this problem, can the body control module be repaired?

i will apreciate your help, very much.
best regards

ramsar 09-13-2011 11:25 AM

Re: Body control module
my car is a 99 jeep grand cherokee laredo, 4.0 L

Frango100 09-13-2011 11:32 AM

Re: Body control module
Both engine temperature and fuel level indicators are getting their signal from the PCM (Powertrain Control Module) and not the BCM.
But do an instrument self test first, to be sure that the instrument cluster is not the problem. With ignition in OFF, push the odometer reset button and while doing so, switch the ignition in on. The instument cluster selftest will be initiated and all instruments will go to full scale and back to normal position. The odometer will count from 00000 to 999999.
For the wipers i have to look into this, will come back later.

ramsar 09-13-2011 11:37 AM

Re: Body control module
Thanks Frank, for yopu advice, how you konw that?, i am going to follow your recomendations, althoug the odometer of my car doent work.

best regards

Frango100 09-13-2011 12:31 PM

Re: Body control module
Most of my information i get out of my jeep service manual. I have a 2004 service manual, but on the following site you can download the 99-04 service manual: (with thanks to cheapjeep Dave:D).
Just discovered however that there are still some minor differences in between this manual and my 2004 one.
It seems however that your instrument cluster has some problems, owing to the fact that your odometer, temp and fuel indicator won't work. Could be as simple as a not completely engaged connector on the cluster though.
An other good site with a lot of helpfull information is:

ramsar 09-13-2011 12:50 PM

Re: Body control module
Thanks a lot frank, i hope one connector is not correct engaged on the cluster, also, i will see the another recommended page you send me, and download the 99 jeep grand Cherokee manual from the site,

Cordials saludos

Frango100 09-13-2011 01:38 PM

Re: Body control module
De nada, estamos aqui por isso.:D

Frango100 09-13-2011 01:50 PM

Re: Body control module
And regarding your windshield wipers, when they function normal in the manual mode, the BCM is ok. When they only won't work in the automatic mode (using the rain sensor), there can be several things wrong. First of all, check if the fuse 25 (15A) on the junction block (below steering wheel) is not blown. Then there is an accessory delay relay which can be faulty (also on the junction block). You could measure on the rain sensor module if you have 12 V on point 5. If this all is ok, there could be a wire problem from/to the rain sensor module (not the supply, because you checked that at point 5), the rain sensor module itself or maybe even the multi function switch.

ramsar 09-13-2011 03:17 PM

Re: Body control module
Hi frank, I have printed the information, I will work today at night in my garage, i hope resolve this problem soon, there is a bad weather here on these days, and i have some problems driving my car when itís raining, itís a little dangerous.
So I have downloaded the repair manual, there are a lot of information regarding my jeep, I appreciate very much your help. I tell you that the windshield wipers doesnít work in a manual mode and automatic mode neither, I going to follow your recommendations,

Su espaŮol es muy bueno,

Thanks a lot

Frango100 09-13-2011 04:47 PM

Re: Body control module
When not working in any mode, check then first fuse 29 on the junction block. If thats ok, remove the wiper on/off relay in the power distribution center under the hood and measure point 87, you should have 12 V overthere (with ignition switch in run or acc). When not, or circuit breaker 1 on the junction block is faulty, or you have a wiring problem. If ok, try to insert a wire on point 85 of the on/off relay and put the relay in place. When connecting this wire to ground, the relay should be energized. If not, relay is bad. You could probably swap it with an other relay for trouble shooting. If relay energized and wiper works, the problem can be in the BCM or wiring to it. If it still doesn't work, there is a good change that the wiper motor is bad.

ramsar 09-15-2011 01:53 PM

Re: Body control module

Hi frank, thanks a lot for your information, i observed the wiper fuse is ok, so I have already checked the relay as you said and it work well, and, I energized the relay connecting with a wire the 85 point to the ground and the wiper worked very well, i just know the wiper is ok and its motor too, now i will proceed with checking the wiring.

i appreciate very much your help,



Frango100 09-15-2011 03:36 PM

Re: Body control module
The on/off relay gets its ground via the BCM. The BCM in its turn receives an input from the multifunction switch. Inside the multifunction switch are several resistors. The BCM could be faulty, but i give it a bigger change that its the multifunction switch. I couldn't find any measurement figures for this switch, but if you measure between point 7 and 8 of the switch connector, you should have the highest resistance in off position and each step of the switch, the resistance should go lower. If you don't measure any resistance on these points, the circuit is open and the switch faulty.
Did you try all the positions of the multifunction switch to see if the wiper would work in any of the positions?

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