Battery draw

Tiny
KELTON98
  • MEMBER
  • 2004 LINCOLN TOWN CAR
  • 89,000 MILES
I have a battery draw that I have traced to fuse 31 of the instrument panel. I completely unplugged the LCM and still have the draw with the number 31 fuse plugged in. I have read there are other fuses in this circuit that could be an issue but I can’t find anywhere detailing which fuses these are and how to continue the test to determine where the draw is coming from. Can anyone help?
Tuesday, March 24th, 2020 AT 5:50 PM

10 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Take a look at this diagram. There appear to be multiple connectors on the LCM. When you say you completely unhook it, you are unhooking all connectors?

If so, I want you to test for continuity on this circuit with all the others. That means, unhook all connectors and with fuse 31 plugged in so you have the draw, and then put one test lead of your meter in this circuit (cavity 25 of the LCM) and then use the other lead to touch each terminal of all the other circuits on the LCM connectors. Have your meter on continuity (the one that beeps when you are touching the same circuit) or ohms. You should have no continuity with any other circuit. If you put it on ohms it should read OL or open/infinite resistance. If you are getting some resistance then between circuits then they are touching and keeping something alive.

Also, what is the draw that you are getting? How many milliamps?
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Tuesday, March 24th, 2020 AT 6:29 PM
Tiny
KELTON98
  • MEMBER
  • 6 POSTS
I was unhooking all 4 connectors and with fuse 31 in place I still had between.40-.80A (not mA) draw. The draw did not change when with or without the LCM hooked up. I am about to check each circuit for continuity and will let you know the results. Thank you for the help!
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Tuesday, March 24th, 2020 AT 7:30 PM
Tiny
KELTON98
  • MEMBER
  • 6 POSTS
If there should be no continuity between any of the wires and the orange/white wire to fuse 31 then there is a serious issue with the car. Almost every wire on each plug had continuity with the orange/ white wire. Please advise.
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Tuesday, March 24th, 2020 AT 8:19 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

With your amp meter hooked up at the negative cable, remove the fuses one by one until the draw drops to 50-75 milli amps. That will narrow the circuit then need to isolate each component on the fuse to find the failure.

https://www.2carpros.com/articles/car-battery-dead-overnight

I would start over.

Why do you suspect the LCM?

Roy

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Wednesday, March 25th, 2020 AT 4:45 AM
Tiny
KELTON98
  • MEMBER
  • 6 POSTS
I know how to trace the draw. I had already done this three times and verified that the draw was coming from fuse 31. I do not suspect the LCM as the draw is not eliminated with the LCM disconnected. I did some more tests and found that there is a short between ground and the orange/white circuit (fuse 31) however this short disappears when you disconnect the harness at the connector that passes through the firewall. The short is non existent on either side of the harness when the connector is disconnected and returns when it is plugged in again.
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Wednesday, March 25th, 2020 AT 11:26 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Okay, got it.

If the orange/white wire was grounded, it would pop the fuse. I think it is more attaching itself to another wire in the harness causing the draw.

That will not be easy tracing down as it runs from the LCM out under the hood as you know. If it is true there is more than 1 wire involved in this.

Roy
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Wednesday, March 25th, 2020 AT 11:56 AM
Tiny
KELTON98
  • MEMBER
  • 6 POSTS
Thanks. Do you have a diagram detailing what components are in the circuit 31? I have now determined that my draw is eliminated when I remove the single connector that the orange/white wire is in from the LCM.
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Wednesday, March 25th, 2020 AT 12:13 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Just what I posted. The LCM is the only component on that circuit.

Okay, if you removed the connector, then it points right to the LCM.

Roy
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Wednesday, March 25th, 2020 AT 12:22 PM
Tiny
KELTON98
  • MEMBER
  • 6 POSTS
The draw is eliminated when removing the one connector from the LCM but the draw remains of you unplug all 4 connectors to the LCM. It’s very strange.
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Wednesday, March 25th, 2020 AT 12:24 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
That is strange but you need them plugged in for the LCM to work.

I still think you need the LCM replaced.

Roy
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Wednesday, March 25th, 2020 AT 12:47 PM

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