Battery drains '97 Concours

[phillips4818]

I've got a problem that's eating my lunch. The battery drains overnight. First thing I did was replace the battery. The problem remained. I took it to my mechanic, not a dealer, but a very experienced professional. He removed the body control module, and the battery still drained. After much troubleshooting, my mechanic determined that the BCM was receiving a signal that the ignition switch was always in the "accessory" position. He removed the ignition switch from the circuit, and the condition remained, the BCM was still receiving a signal that the switch was in "accessory" position. So that's the problem. Doesn't seem to be the BCM or the ignition switch. Does it sound like a simple short in one of the many miles of wires in the car. Help!

[Cadillac Jim]

One thing that may help is reading the OBD II codes. Please read them and post them here. Here's how:

http://www.caddyinfo.com/readingcodes.html

According to the 1997 FSM, pages 8A-10-3 and 8A-51-1, the ignition accessory switch provides a switched power line on the ignition switch connector terminal C6 to a brown wire that is hot when the key is the in ACC and RUN positions. This brown wire goes to the trunk compartment fuse bock through the ACC fuse, which is a 10 Amp, which then goes on a yellow wire to the BCC terminal A10.

Page A8-11-1 shows a diagram of the fuses in the trunk compartment fuse block and the ACC fuse is in the left row, third from the top. You can check the ignition ACC switch by pulling this fuse and seeing if you have voltage on terminal C14, the brown wire, when the key is not in RUN or ACC. If you do, switch is bad or you have a short to hot on the brown wire. If you pull this fuse and still see voltage on the other fuse terminal C13, or on the BCM terminal A10, there may be a short to hot in the circuits involving the automatic day-night mirror or outside moisture sensor circuits.

A short to hot is very rare. I would start with checking the connectors themselves to make sure that the short isn't there, and that the connectors are placed correctly (not pushed into the connector) and are clean and tight.

[phillips4818]

One thing that may help is reading the OBD II codes. Please read them and post them here. Here's how:

<a href="http://www.caddyinfo.com/readingcodes.html" target="_blank">http://www.caddyinfo.com/readingcodes.html

</a>

According to the 1997 FSM, pages 8A-10-3 and 8A-51-1, the ignition accessory switch provides a switched power line on the ignition switch connector terminal C6 to a brown wire that is hot when the key is the in ACC and RUN positions. This brown wire goes to the trunk compartment fuse bock through the ACC fuse, which is a 10 Amp, which then goes on a yellow wire to the BCC terminal A10.

Page A8-11-1 shows a diagram of the fuses in the trunk compartment fuse block and the ACC fuse is in the left row, third from the top. You can check the ignition ACC switch by pulling this fuse and seeing if you have voltage on terminal C14, the brown wire, when the key is not in RUN or ACC. If you do, switch is bad or you have a short to hot on the brown wire. If you pull this fuse and still see voltage on the other fuse terminal C13, or on the BCM terminal A10, there may be a short to hot in the circuits involving the automatic day-night mirror or outside moisture sensor circuits.

A short to hot is very rare. I would start with checking the connectors themselves to make sure that the short isn't there, and that the connectors are placed correctly (not pushed into the connector) and are clean and tight.

[navion]

I've got a problem that's eating my lunch. The battery drains overnight. First thing I did was replace the battery. The problem remained. I took it to my mechanic, not a dealer, but a very experienced professional. He removed the body control module, and the battery still drained. After much troubleshooting, my mechanic determined that the BCM was receiving a signal that the ignition switch was always in the "accessory" position. He removed the ignition switch from the circuit, and the condition remained, the BCM was still receiving a signal that the switch was in "accessory" position. So that's the problem. Doesn't seem to be the BCM or the ignition switch. Does it sound like a simple short in one of the many miles of wires in the car. Help!

The first thing that I would do would be to check the glove compartment light (if so equipped) and the trunk light to make sure that they are turning off when they are closed.

I have seen this simple problem drive even good mechanics to distraction.

Britt

[BodybyFisher]

I know that this members dead battery hard starting happened in cold weather but I was reminded of this thread

http://caddyinfo.ipbhost.com/index.php?showtopic=16335

Check to see if the retained power circuits are turning off. I am not sure if that is the name for it, but if you turn the key off, and sit in the car, the radio and windows will work for about 10 minutes and then shut off, check to see if your power does shut off....

[phillips4818]

Would you be willing to fax me the pertinent pages from your 1997 FSM?

One thing that may help is reading the OBD II codes. Please read them and post them here. Here's how:

<a href="http://www.caddyinfo.com/readingcodes.html" target="_blank">http://www.caddyinfo.com/readingcodes.html

</a>

According to the 1997 FSM, pages 8A-10-3 and 8A-51-1, the ignition accessory switch provides a switched power line on the ignition switch connector terminal C6 to a brown wire that is hot when the key is the in ACC and RUN positions. This brown wire goes to the trunk compartment fuse bock through the ACC fuse, which is a 10 Amp, which then goes on a yellow wire to the BCC terminal A10.

Page A8-11-1 shows a diagram of the fuses in the trunk compartment fuse block and the ACC fuse is in the left row, third from the top. You can check the ignition ACC switch by pulling this fuse and seeing if you have voltage on terminal C14, the brown wire, when the key is not in RUN or ACC. If you do, switch is bad or you have a short to hot on the brown wire. If you pull this fuse and still see voltage on the other fuse terminal C13, or on the BCM terminal A10, there may be a short to hot in the circuits involving the automatic day-night mirror or outside moisture sensor circuits.

A short to hot is very rare. I would start with checking the connectors themselves to make sure that the short isn't there, and that the connectors are placed correctly (not pushed into the connector) and are clean and tight.

[Cadillac Jim]

I'll scan them in and put them up tomorrow. However, your best information is from the OBD II codes. Please do run them, write them down, and post them here. It only takes a few minutes.

[Cadillac Jim]

I'm not getting to this and it's a big deal for me to scan several pages from the FSM, fix it up for posting in Photoshop, and put them on Photobucket, and get the post up. Anyone who can get it done before the weekend please chime in. Otherwise I'll get it done Saturday.

[Cadillac Jim]

These are the referenced FSM pages referenced in post #2: