SteelHeadz
Super Moderator
Do you know what circuits are on this C838 connector?. It will sure help narrow down my search to help you out.
MUX/T TOW fuse draining battery
- Thread starter RCJP
- Start date
I meant C383 "Door Ajar Switch/Seat belt/Parking Brake" It was previous talked about on this thread, he said it was a bad sensor creating a draw on the battery. I believe I have the same problem, my Jeep claims the back gate is constantly open and its battery keeps going dead. Can you please help me locate this sensor.
SteelHeadz
Super Moderator
The circuit he's reffering to is the ajar switch. It's located on the liftgate behind the panel.
SteelHeadz
Super Moderator
let me know if there's anything else i can help you with.
IA_Chiefs_fan
New member
Okay guys, I have a friend who has a 1998 Jeep Grand Cherokee. He asked for help because his battery was draining. A search landed me here a few days ago. I have been trying to follow along with my limited mechanical abilities and determined I have an issue with a specific wire in the white plug on the BCM. It is the purple wire (top left or bottom right depending on how you are holding the plug). I determined this by using a multi-meter on the battery as previously explained. Then I took a 6" piece of 16 guage electrical wire and pulled the wire through a little leaving a quarter inch at one end in which there was a hole prior to the wire. I slid this over the prong on the BCM while sticking the bare end of the wire in the corresponding port of the plug. All read around 9-10 Ma except the purple wire which read 104. I am exhausted but hopefully I'm getting close now. Can someone offer some further guidance please?
P.S. I'll make him bookmark this site for future reference!
P.S. I'll make him bookmark this site for future reference!
SteelHeadz
Super Moderator
If it's a solid purple wire, it's a fused positive signal wire from the junction block, Fuse#7, 20 amps.
IA_Chiefs_fan
New member
Okay, so what's my next step in tracking this down? I was hoping someone would say the purple wire runs to the "___".
SteelHeadz
Super Moderator
One end of the purple wire is connected to the Junction block and the other end is to the Body control module.
IA_Chiefs_fan
New member
Right, but I'm not certain what my next step is still. I apologize if I'm missing the obvious. This project has been very frustrating. Thanks for the help!
SteelHeadz
Super Moderator
Have you already checked the rear gate ajar switch for a stuck closed condition?
IA_Chiefs_fan
New member
I think so, but will tell me the proper way to check it?
SteelHeadz
Super Moderator
With the rear gate door panel removed, trace the Tn/Bk wire. There should be a connector there to the latch assembly. Disconnect the wire connector and perform a continuity test between the Tan and Black wire to the body ground. If the continuity status changes as you open and close the gate, the switch is good. If not, replace the switch.
Another way to know if it is a door sw is to meassure the current on the Mux/t/ tow fuse on the power distribution center (read above for location of the mux/t tow.) this is the test
set the multimeter to high range current (with at least one door open)
it should read around 200~300mA.
close all doors and disconect the under-hood light.
lock them with the remote (you will see a temp current spike around 1A)
then it will read the 200~300mA again.
if after a minute this current does not go to 10~20mA that means the BCM is still "awake".
next disconect the small black connector from the BCM this connector has all the door sw, liftgate sw, lifgate window sw and the hand bracke sw.
performe the test again and if this time the current does go down, check on the connector to see wich pin is grounded (close all doors for this.)
good luck
I've got a 98 Grand Cherokee Laredo, 4X4, with the 318.
I just wanted to say thanks. This thread helped me track down a problem that's been vexing my jeep for a while now. I knew it was the MUX/T Tow fuse, I knew it was the #7 fuse, and I could isolate things also with the circuit breaker. After 2 hours of tracking stuff down I disconnected the bottom connector to the BCM. Finally the current draw was reduced and I knew I had gotten the BCM to sleep. I had a feeling it was either the lift gate switch or the rear window switch. When I disconnected either one the BCM would still stay awake. But after I disconnected both it went asleep.
After messing with the switches I found the rear window switch to be loose. I reconnected it and left the lift gate switch off. Bingo. It's the rear gate switch, which doesn't surprise me because I've been having issues with the whole assembly for awhile now.
Anyways, thanks again for your diagrams, diagnostics, and explanations.
P.S. Don't be fooled by the ticking noise coming from the courtesy lamp relay. Mine started to tick as the battery started to die and I had one of the doors open.
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SteelHeadz
Super Moderator
Your welcome. We are glad to help and Welcome to Jeepz..
This thread has helped me so much i feel i need to contribute. I have a 1998 grand cherokee limited.
Thanks to Steelheadz, and RCJP for posting the diagrams. I couldn't have done this without them.
anyway been having the 220ma draw on the battery killing it like everyone. started narrowing it down with fuses. reading online. Once we got the pinout for the bottom black plug on the BCM we were able to test the doors. the doom lights would stay on all the time and the previous owner had pulled the fuse.
we couldn't get the bcm to go to "sleep" always pulling around 200ma.
What we found was the purple/yellow wire or pin 10 on the bottom black plug was always grounded. the paper says "to door and liftgate vtss disarm switches". We did have the rear gate all torn apart and tested the latch sensors on the gate and window and seemed to be working fine. So we just cut the purple/yellow wire and the interior lights went out and bcm went down to 30ma and then 15ma. Now when we open the gate or window the interior lights don't come on but we don't really give a crap. no more dead battery. interior lights do come on with the doors thou.
from what i know the disarm switch should be connected where you put the key in, so not sure why its somehow connected to the gate/window sensor open sensors. whatever its fixed. Hope that helps someone else.
Thanks to Steelheadz, and RCJP for posting the diagrams. I couldn't have done this without them.
anyway been having the 220ma draw on the battery killing it like everyone. started narrowing it down with fuses. reading online. Once we got the pinout for the bottom black plug on the BCM we were able to test the doors. the doom lights would stay on all the time and the previous owner had pulled the fuse.
we couldn't get the bcm to go to "sleep" always pulling around 200ma.
What we found was the purple/yellow wire or pin 10 on the bottom black plug was always grounded. the paper says "to door and liftgate vtss disarm switches". We did have the rear gate all torn apart and tested the latch sensors on the gate and window and seemed to be working fine. So we just cut the purple/yellow wire and the interior lights went out and bcm went down to 30ma and then 15ma. Now when we open the gate or window the interior lights don't come on but we don't really give a crap. no more dead battery. interior lights do come on with the doors thou.
from what i know the disarm switch should be connected where you put the key in, so not sure why its somehow connected to the gate/window sensor open sensors. whatever its fixed. Hope that helps someone else.
With the connector disconnected, I get continuity between the black and tan wire. Is this normal. Also, I get continuity between the two corresponding pins of the switch no matter what position the latch is in. The switch is bad right?
1998 Grand Cherokee 4x4, 4.0L 6 cyl.
180mA current over MUX/T TOW fuse (50A) draining the battery. After reading the above replies I traced the problem to the tailgate glass door switch near the unlocking solenoid: the crimp came undone and the switch no longer indicated the closed position. Problem fixed.
THANK YOU ALL!
180mA current over MUX/T TOW fuse (50A) draining the battery. After reading the above replies I traced the problem to the tailgate glass door switch near the unlocking solenoid: the crimp came undone and the switch no longer indicated the closed position. Problem fixed.
THANK YOU ALL!
**the short answer in this case was the key switches on the drivers and front passenger doors** but read on for a complete version.
I too had this problem, until tonight. If you know your way around a VOM read on and see my diagrams and you will have this fixed in no time. By probing the purple and yellow wire, (Pin 10) on the bottom black 14-pin bcm connector, (C383 in the diagram in the post linked to herein) the one you can get to without removing the bcm, I could see that the wire was sensing a ground, meaning one of the three door cylinder switches was grounded and telling the BCM to disarm. You can also check all the other door/rear window sensor inputs at this connector.
The only ones that should show a ground are Pin 8 Ground and maybe the seat belt sensor( i havent figured that out yet but it will not effect the lights or alarm).
Suspecting the drivers door lock cylinder switch, I pulled the canopy off the door and unplugged it, that connector is right at the bottom of the door. Immediately the ground signal at the purple and yellow above-mentioned wire went away and I knew I nailed it.
The door lock switch was grounding out or stuck on ground, telling the system to disarm. I put it back together and for the first time since I owned it everything, and I mean everything worked. Interior lights, fade after 20 seconds, the ring around the key, all the chimes, and the alarm even armed when I used the lock switch on the door. It lock and unlock with the fob, the interior lights came on with the fob, the red led blinks on the dash, and the panic button worked. Even the previous owner was stumped by this and had pulled the fuse for the lights.
Best of all the current drain went from 200ma, to 30ma, and to 10ma finally, and the bcm was asleep and not draining my battery. I did not have to use the $10 bcm I got at the junkyard earlier at all. It would have screwed up the odometer anyhow. Ill return it and get something else.
I found a very helpful diagram with pin numbers, wire colors, and function table of the black connector and probed each input for the appropriate signal. I totally recommend you take your multimeter and check the sensor signals for the purple and yellow 'disarm' wire and to the doors and rear window. Mine were ok except for the disarm wire. The link to that is here, scroll to the bottom of the post:
Installing a ZJ/XJ overhead console: - NAXJA Forums -::- North American XJ Association
This diagram, half way down, will show you the block picture of the bcm inputs: http://www.justanswer.com/jeep/7j4hf-grand-cherokee-disable-alarm-97-grand-cherokee.html
**If you suspect any of the relavant sensors are bad, simply disconnect them until you can repair or replace them. The system wants to see an open circuit on all of them to operate normally.
Two things that will make this tons easier are 1) have a backup supply of fuses for your small ammeter which will blow them if you try to measure your battery voltage when in the 10 amp configuration, I am an electrician and I still popped about 5 of them, but the MOST IMPORTANT HELPFUL thing I found was 2)
INSTALL A BATTERY DISCONNECT SWITCH. IT WILL MAKE THE PROCESS 100 TIMES EASIER AND IS HANDY TO HAVE, IF MAYBE A LITTLE UNSIGHTLY. Also if your alarm goes off while your repair is in progress, usually a few days to round up parts etc; you can just switch off thewhole car and reset it if your door key switches aren't working, until you fix them. I INSTALLED MINE ON negative cable on the underside of the left front bumper. Saves A LOT of time and aggravation ...putting your ammeter inline with the battery and taking it out, and with troubleshooting etc. Also a light wire to the + battery so you can use your voltmeter under the dash to check those signals on the black connector. Hope this saves you $$$'s and puts you back in shape like it did me.
I too had this problem, until tonight. If you know your way around a VOM read on and see my diagrams and you will have this fixed in no time. By probing the purple and yellow wire, (Pin 10) on the bottom black 14-pin bcm connector, (C383 in the diagram in the post linked to herein) the one you can get to without removing the bcm, I could see that the wire was sensing a ground, meaning one of the three door cylinder switches was grounded and telling the BCM to disarm. You can also check all the other door/rear window sensor inputs at this connector.
The only ones that should show a ground are Pin 8 Ground and maybe the seat belt sensor( i havent figured that out yet but it will not effect the lights or alarm).
Suspecting the drivers door lock cylinder switch, I pulled the canopy off the door and unplugged it, that connector is right at the bottom of the door. Immediately the ground signal at the purple and yellow above-mentioned wire went away and I knew I nailed it.
The door lock switch was grounding out or stuck on ground, telling the system to disarm. I put it back together and for the first time since I owned it everything, and I mean everything worked. Interior lights, fade after 20 seconds, the ring around the key, all the chimes, and the alarm even armed when I used the lock switch on the door. It lock and unlock with the fob, the interior lights came on with the fob, the red led blinks on the dash, and the panic button worked. Even the previous owner was stumped by this and had pulled the fuse for the lights.
Best of all the current drain went from 200ma, to 30ma, and to 10ma finally, and the bcm was asleep and not draining my battery. I did not have to use the $10 bcm I got at the junkyard earlier at all. It would have screwed up the odometer anyhow. Ill return it and get something else.
I found a very helpful diagram with pin numbers, wire colors, and function table of the black connector and probed each input for the appropriate signal. I totally recommend you take your multimeter and check the sensor signals for the purple and yellow 'disarm' wire and to the doors and rear window. Mine were ok except for the disarm wire. The link to that is here, scroll to the bottom of the post:
Installing a ZJ/XJ overhead console: - NAXJA Forums -::- North American XJ Association
This diagram, half way down, will show you the block picture of the bcm inputs: http://www.justanswer.com/jeep/7j4hf-grand-cherokee-disable-alarm-97-grand-cherokee.html
**If you suspect any of the relavant sensors are bad, simply disconnect them until you can repair or replace them. The system wants to see an open circuit on all of them to operate normally.
Two things that will make this tons easier are 1) have a backup supply of fuses for your small ammeter which will blow them if you try to measure your battery voltage when in the 10 amp configuration, I am an electrician and I still popped about 5 of them, but the MOST IMPORTANT HELPFUL thing I found was 2)
INSTALL A BATTERY DISCONNECT SWITCH. IT WILL MAKE THE PROCESS 100 TIMES EASIER AND IS HANDY TO HAVE, IF MAYBE A LITTLE UNSIGHTLY. Also if your alarm goes off while your repair is in progress, usually a few days to round up parts etc; you can just switch off thewhole car and reset it if your door key switches aren't working, until you fix them. I INSTALLED MINE ON negative cable on the underside of the left front bumper. Saves A LOT of time and aggravation ...putting your ammeter inline with the battery and taking it out, and with troubleshooting etc. Also a light wire to the + battery so you can use your voltmeter under the dash to check those signals on the black connector. Hope this saves you $$$'s and puts you back in shape like it did me.
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