Battery draining for past 8 months

[witsend]

My bf bought a 2000 Cadillac Catera in Jan last year.

In May we started having problems. If left a few days the battery would die. We jumped it. The problem got progressively worse until it would die if left for 5 min while we were in the grocery store.

We took it to the dealer who quoted $1100 to fix the body control module. We said no we'll get a second opinion and they added that the battery was also bad (this seemed a little sketchy on their part which is why we didn't go back to them). We had them replace the battery and hoped for the best. It was better for a few weeks (we were driving it daily) slowly it got progressively worse until it was really bad again.

So in August we took it to an Electronics specialist (we are in Sacramento, CA - we were recommended to take it to CA Rewire). They also said it was the Body Control Module and charged $900 to replace the BCM and the battery (which had again been ruined from repeated jumps and recharges).

We then took a 2 week vacation and the car was fine (we drove it daily). When we got back my bf was out of the country for a month. 5 days in his roommate tried to move the car and it was dead. So when he got back we charged it and hoped for the best. It continued to die if left for 4-5 days. So we took it back to the Electronics place in November. They had it for 2 wks and said it never dropped charge at all (which I don't understand at all - they either moved the car around every few days or are lying). So we paid $90 for their time and brought it home.

Of course, it continued to die. Now its really bad again, dying after being left only a few hours.

I'm really at my wits end with this. I just want the car to start and stop like its supposed to. I don't want to take it back to the electronics place just to pay $90 to be told "there is no problem." But if I take it back to the dealer will the warranty on the body control module hold? Or will we have to pay for it all over again?

Any suggestions on what it could be? What I should look at myself? Or where I can take it and avoid spending more than the $1200 we've already spend on this car.

Thank you so much for any help!

[witsend]

Anyone have any thoughts?

If nothing else, does anyone know what will happen to the part warranties if I take the car to the dealer to be repaired instead of back to the electronics place?? Will I have to pay for the parts all over again or will the dealer pursue the warranties for me so I don't have to worry about it?

[Marks DTM Calib]

First thing to do....get a volt meter and measure the battery voltage with the engine revving (3000+rpm).......report back the findings.

My first guess without this reading wuld be a failed alternator reg which is overcharging the battery and slowly cooking it......piss poor diag work by the dealer so far though.....

Also, check the boot light is turning off, leave the ski hatch open and shut the boot as an easy way to check.

[witsend]

Originally Posted by Marks DTM Calib

First thing to do....get a volt meter and measure the battery voltage with the engine revving (3000+rpm).......report back the findings.

14.3V

Also, check the boot light is turning off, leave the ski hatch open and shut the boot as an easy way to check.

Yeah we did this when it first started months ago - it doesn't stay on - nor does the glove box light.

Thanks for your reply and any additional info you might have.

[Marks DTM Calib]

Thats fine....can you measure the current drain from the battery with an ammeter whilst the engine is off and doors closed.......?

Repeat with it locked (might need to disconnect the bonnet switch in the engine bay to stop the alarm sounding).

Any aftermarket fitments ie radio, alarm etc?

[witsend]

Originally Posted by Marks DTM Calib

Thats fine....can you measure the current drain from the battery with an ammeter whilst the engine is off and doors closed.......?

Right now its about .01 V every 5 seconds or so.

Repeat with it locked (might need to disconnect the bonnet switch in the engine bay to stop the alarm sounding).

Same, .01V every 5 sec

Any aftermarket fitments ie radio, alarm etc?

Nope, none. Although the factory CD changer has been jammed for a long time.

[graphicsman]

Could be the motor in the changer whirring away. If this is the changer in the trunk, see what happens if you unplug it.

[witsend]

Originally Posted by graphicsman

Could be the motor in the changer whirring away. If this is the changer in the trunk, see what happens if you unplug it.

Yeah thats what we were thinking. We're gonna try that too. I was just gonna pull the fuse and see if that worked, but the fuse runs the headlights, taillights and blinkers too so that wouldn't work.

The problem got to the point where it shot the battery to hell again, so we're getting that replaced. I can't do too much testing until then because right now the battery itself can't hold charge.

But if anyone else has any ideas to try I'll be eternally grateful. I really wish I understood cars better and could do this better myself.

[Marks DTM Calib]

Well my next step would have been to monitor the current (which will be in Amps not Volts) and pull fuses one by one.....

[heavycat]

I was having the same problem with my 2000,I was killing batterys very frequently, i figured out that its was as simple as running a new 4 gauge power from the alternator to the battery. The original wire had burnt itself right through the shielding. I left the factory wire in, and ran the new one carefully away from hot spots. Apparantly the factory cable was undersized for the vehicle. hope this helps,