HUGE Battery Drain

[bmdubya1198]

Back again with another unrelated battery drain issue! This time, it's definitely not alternator related (disconnecting B+ terminal changes nothing). My brother has been driving the car daily for the past week or two, then he took his other car a few days ago. Went to start the E34, and when it started the hazards and wipers came on and wouldn't turn off until the key was removed, so he just took his Volvo again. Went to move it to the garage the other day, and it was totally dead. Had to jump it, and it took a LOT to get it to crank up. Moved it into the garage, and the battery was totally flat the second I turned the car off.

Come today, after the battery showed a whopping 0.5V (this was a good 2 year old battery, by the way). After several drains (separate issues with the voltage regulator before this), I figured it would be best to just get a new one. Went and picked up a new battery, and I connected my meter to see an outrageous 14 amp draw! Normally I'd pull fuses, but I didn't want to blow the fuse in my meter by keeping it on for too long since it's only fused for 10A.

I first checked the central locking fuses and GM, since there have been some strange issues regarding that system. No difference.

I'll get into that too... the power locks don't work, and there are some weird things going on with them. If I lock the passenger door with the key, occasionally the windows and sunroof won't work. I have to get out and unlock the door, open it, then the interior lights come on and the windows work. I tested the micro switched on the lock cylinders, and they both work. I attempted to remove the driver door lock actuator, but I can't figure out how to get it out from behind the window track.
I checked the fusible link next to the battery, and while there's some corrosion on it, it shows 0 ohms of resistance.

Anybody have any ideas? I'd love to try to diagnose this with some sort of software, but I haven't found clear info for MY 1995 E34s. The earlier ones at least have the option of the stomp test, but on here I have no idea how to go about it. I have INPA with a K+DCAN cable and pac-man adapter, but I believe the E34 requires a different cable.

[shogun]

stomp test is only engine related, not for such electric problem.
Maximum closed current by vehicle
E31 50mA
E32 50mA
E34 40mA
E36 30mA
E38 50mA
E39 40mA
E46 40mA
E52 50mA
E53 40mA
Z3 30mA

Performing Closed Current Draw Test
• Select proper measuring device (DISplus, MoDic or DVOM),Remember amperage draw in excess of 10A will damage DVOM.
-Use inductive amp probe of DISplus when amperage draw is high.
-When using DISplus inductive probe, clamp on negative battery cable with arrow pointing away from battery. Switch off all consumers. (It is not necessary to disconnect B- from body when using inductive probe)
• Connect (-) test lead to negative battery terminal and (+) test lead to a known good ground.
• Ensure all systems are OFF !
• Be sure DVOM is on and set in proper mode.
• Disconnect battery ground lead from body.
• Observe meter reading, wait for vehicle to enter sleep mode.
• Identify faulty circuit by disconnecting fuses, relays, control modules or connectors, observing meter readings.
• Defective circuit is found when current is below maximum closed current for vehicle being tested.

http://www.e38.org/battery.pdf

[6erWEBB]

Pull a fuse, wait overnight, recharge if necessary, replace and remove next fuse until drain is found? That’d be the simple way.

[bmdubya1198]

Right, but I would think there's a way for the GM to store codes of some sort. E34s are way more advanced than I would have thought they were prior to working on one. At least with my E39, diagnostic software actually works with it!
I'll see what I can do.

- - - Updated - - -

Pull a fuse, wait overnight, recharge if necessary, replace and remove next fuse until drain is found? That’d be the simple way.

It'll work, just time consuming, and I don't want to kill the new battery. I guess I could just pull one at a time, then check to see if the draw is lower.

[prettyfoot]

With a draw that large I would look at voltage drop across fuses. You won't need to pull them, just put your meter on either side of the back of the installed fuse. The fuses the e34 use make this really easy. A lot of European makes call for this type of parasitic draw test because pulling and reinstalling fuses can cause modules on a network to "wake up" giving you misleading results. I dont know what type of meter you have but usually I'd be in mV scale. There's lots of good info and videos on using voltage drop to check parasitic draws, hopefully with such a large draw it will jump out at you.

Sent from my SM-G970U using Tapatalk

[bmdubya1198]

Good call, I’ll try that tomorrow. I’m hoping you’re right about it quickly revealing itself!

[6erWEBB]

Prettyfoot with the technique!! That way sounds much better haha. Yeah if you’ve got a draw that big as soon as you can find what circuit it’s in I’ll bet it’ll be pretty obvious.

[bmdubya1198]

Just checked the voltage drop across all the fuses, can’t find anything suspicious. Weird. The only thing I notice when I connect the battery is a relay click sound somewhere in the car, but I can’t pinpoint it. It clicks every 5-10 seconds or so.

[moroza]

GM does not store codes.

One click is normal when connecting the battery. Every 5-10 seconds is not.

Got wiring diagrams? If the voltage drop technique doesn't work, read the Power Distribution section and proceed systematically, starting by isolating whether the problem is the rear or front power distribution.

Vague hunch says your data link circuit is frying things. Unplug the diagnostic cap and see if that changes anything.

[bmdubya1198]

I'll look into the DLC. I was looking over the diagrams last night, but I haven't had a chance to really look at anything on the car too in depth. I should be able to take a closer look today.

[demetk]

Just checked the voltage drop across all the fuses, can’t find anything suspicious. Weird. The only thing I notice when I connect the battery is a relay click sound somewhere in the car, but I can’t pinpoint it. It clicks every 5-10 seconds or so.

Heater control valve clicks on/off every couple of seconds. Maybe pull all fuses and check amp draw across each fuse holder.

[moroza]

Heater control valve clicks on/off every couple of seconds. Maybe pull all fuses and check amp draw across each fuse holder.

Only when the ignition is on, blower fan is on, and heat setting is not maximum.

[demetk]

Unless he has a short to voltage.

[bmdubya1198]

Happy to report I got this figured out today! After pulling a 30A fuse in the rear distribution box (don't remember the specific number), the draw went down to a normal range. Checked the circuit, and ended up at the passenger seat. The slide adjustment switch was jammed in the back position against the seat trim. That'll do it! I snapped it back in place (actually removed the knob/switch since the trim would just allow it to happen again), replaced the fuse, and sure enough the draw was back down to normal.
Thanks for the guidance everybody!

[shogun]

Fuses 41 + 42 30A under rear seat is for power seats. Other 30A fuses under rear seat are for ZKE locking, ZKE power windows, electric steering column

[6erWEBB]

Nice work!!! So glad you stuck with it, problems like this can become overwhelming quickly.

[bmdubya1198]

They certainly can! I was really happy to find that so quickly. I just went rapid fire pulling every fuse over 15a and I quickly found it once I got to the rear box.

I believe it was fuse 42.

[TiagE39]

Nice! Was following this for the last few days, glad to see a happy ending.

Make sure to test your power seats in every direction. I have spare E34 seat motors (non-memory) if you burnt one out, no need for them.

[bmdubya1198]

Nice! Was following this for the last few days, glad to see a happy ending.

Make sure to test your power seats in every direction. I have spare E34 seat motors (non-memory) if you burnt one out, no need for them.

Thanks! I need to pull apart the seats at some point and fix the twisted backs. All adjustments seem to work otherwise, fortunately. I’ll definitely let you know if I end up needing any!

[ross1]

Happy to report I got this figured out today! After pulling a 30A fuse in the rear distribution box (don't remember the specific number), the draw went down to a normal range. Checked the circuit, and ended up at the passenger seat. The slide adjustment switch was jammed in the back position against the seat trim. That'll do it! I snapped it back in place (actually removed the knob/switch since the trim would just allow it to happen again), replaced the fuse, and sure enough the draw was back down to normal.
Thanks for the guidance everybody!