12A Battery Drain on Fuse 20

[CallMePuff]

Hello again,

I've got a '95 525i that has a 11-12A drain on the battery with the ignition off.

I've noticed the interior lights will randomly come on at night when the cars off.

I've searched around and done the following to no avail:

Disconnected CCM
Disconnected OBC
Disconnected Climate controls
Disconnected the HVAC module (3 plugs on the center console near the cabin filter?)
Checked to make sure boot/trunk light stays off

I'm unsure where the gauge cluster plug is, as there's a mess of plugs underneath the driver's side.

Does anyone have any idea what could be drawing this much power?

Thanks in advance!

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[Ateyourv8]

Here's a diagram of all that is connected to Fuse F20 (20amp) in the front fuse box. Your heater/ac blower isnt on by any chance when you remove the key? Ive seen that happen and cause a parasitic drain. It has to be something major since the draw isnt small.
Capture.JPG

[CallMePuff]

Here's a diagram of all that is connected to Fuse F20 (20amp) in the front fuse box. Your heater/ac blower isnt on by any chance when you remove the key? Ive seen that happen and cause a parasitic drain. It has to be something major since the draw isnt small.
Capture.JPG

That would be like the AC button being pressed, right? That's a great schematic! The parts I haven't checked are the instrument cluster (which I'm sort of unsure how to check. Won't removing it cause an SRS issue?), the park heating ventilation relay box (have to look this one up), chime module, water valves.

Like I'd mentioned before, I BELIEVE I checked the IHKR module, but I was unable to find a picture that looks like my setup. I pulled the passenger side and saw, right next to where the interior filter is, a module that had 3 plugs in it. I pulled it out and ran the part number at it was a "General Comfort Module" which didn't at all sound like an IHKR but it was in the spot where I'd found online, though not identical.

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[shogun]

Most of the pin assignments you can see from the ETM http://shark.armchair.mb.ca/~dave/BMW/e34/e34_94.pdf

The control unit for the heating and cooling is located behind the interior filter, on my E32 which has a IHKA, there are 2 plugs on driver side and 2 plugs on passenger side. Not sure about the IHKR. Based on this link it also has 4 plugs https://www.ebay.com/p/BMW-E34-535i-...990/1042372308
I only have the pinout for the IHKA http://www.bimmerboard.com/forums/posts/426626/

EDIT:
5 Series - E34 (518i, 520i, 525td, 525tds, incl. touring) Schematics Model year 1994
Automatic climate control with filter (IHKR/F3)
Scheme 6450.5
A=X18155 26-pin, white
B=X18156 26-pin, black
C=X18157 26-pin, blue

https://download.bmwland.ru/valera/E...0.5/index.html

Parked ventilation info http://www.bmwe34.net/E34main/Upgrade/Ventilation.htm

Instrument cluster you can pull out after you have disconnected the battery, then no SRS light trouble.
http://www.bmwe34.net/E34main/Mainte...Capacitors.htm
cluster pinout for all cluster versions, grey, white, blue backplate http://www.e32-schrauber.de/bmw/s-stecker-kombi.htm

[ross1]

TWELVE! amps? It is(or should be) a 10a fuse on that circuit. The heater valves if left on would draw about the most current of anything on that circuit. However, unless it is shorted something else(IHKR)is commanding it to be "on". I'd disconnect it and see if the draw remains.

If truly drawing that much current all you need to do is find the warm wire.

[CallMePuff]

TWELVE! amps? It is(or should be) a 10a fuse on that circuit. The heater valves if left on would draw about the most current of anything on that circuit. However, unless it is shorted something else(IHKR)is commanding it to be "on". I'd disconnect it and see if the draw remains.

If truly drawing that much current all you need to do is find the warm wire.

Right?! I'm not quite sure what's going on.

I pulled this picture from Google. I thought the IHKR module was located where that group of wires on the right go. Is that correct?

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[ross1]

Right?! I'm not quite sure what's going on.

I pulled this picture from Google. I thought the IHKR module was located where that group of wires on the right go. Is that correct?

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That's it. It is held by a clip, look around you'll see how it slides out.

[CallMePuff]

That's it. It is held by a clip, look around you'll see how it slides out.

Yeah I pulled it out, had 3 plugs attached to it.

I ran the part number on it and it came up as a General Comfort Module. Is that correct?

The battery drain didn't stop after that.

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[Ateyourv8]

I agree on the heater valves drawing the most power of anything. They are located under the hood IIRC. Unplug them and see if anything changes. Also if you or a friend happen to have a thermal imager, that would help to diagnose it rather quick. Since the wire drawing power would leave a heat trace while the other wires would be off, itd be rather easy to find.

[ross1]

Are there any aftermarket accessories such as alarm or cell phone connected to that circuit?

[CallMePuff]

Are there any aftermarket accessories such as alarm or cell phone connected to that circuit?

I've got an aftermarket head unit and a subwoofer, but the drain was occurring long before that addition.

I unplugged the radio and the drain still existed, and the subwoofer amp is only on when the ignition is turned.

When I pulled the back seat, there is a security module on top of that fuse box, but as far as I know the alarm system hasn't worked during my yearlong ownership. Could this be it?

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[ross1]

When I pulled the back seat, there is a security module on top of that fuse box, but as far as I know the alarm system hasn't worked during my yearlong ownership. Could this be it?

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Sounds like the factory unit. Not served by the circuit in question.
Are you sure the draw from is only that circuit? It goes away if you pluck the fuse out, right.

[CallMePuff]

Sounds like the factory unit. Not served by the circuit in question.
Are you sure the draw from is only that circuit? It goes away if you pluck the fuse out, right.

I checked all of the fuse circuits in the front fuse box (besides all of the very large fuse/relays) and fuse 20 was the only one pulling NEARLY that many amps. I'll have to check the heater valves when I get home from work.

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[CallMePuff]

Hi,

I've come back to this thread to admit my idiocy...

When I was reading my multimeter, I had it set up to only read DC Voltage and not Amps, so I was reading 11-12V on fuse 20. Switched it to Amps tonight and 20 draws nothing.

I switched it to the CORRECT setting and I'm draining 43mA off the battery. I'm going to start pulling fuses again and measuring the battery.

Consider this my formal apology to all the folks that have sent me schematics and provided insight.

I still am not sure if 43mA is normal drain.



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[shogun]

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.

use this link for more details http://www.e38.org/battery.pdf

[ross1]

Hi,

I've come back to this thread to admit my idiocy...

When I was reading my multimeter, I had it set up to only read DC Voltage and not Amps, so I was reading 11-12V on fuse 20. Switched it to Amps tonight and 20 draws nothing.

I switched it to the CORRECT setting and I'm draining 43mA off the battery. I'm going to start pulling fuses again and measuring the battery.

Consider this my formal apology to all the folks that have sent me schematics and provided insight.

I still am not sure if 43mA is normal drain.



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This explains how a 10a fuse managed to pass 12 "amps".

[CallMePuff]

This explains how a 10a fuse managed to pass 12 "amps".

Yeah that was a little confusing, eh? I'll make that mistake once and only once.

Still have a slight drain at 43mA and got no current through the fuses in the front box while the car's off.

The search continues


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[demetk]

You're now going to search for the additional 3mA?

[ross1]

What started this whole adventure anyway? The interior lights coming on at night?
Not sure how you noticed this but lifting the door handle will turn the lights on. Perhaps some potential thieves in your neighborhood?
I caught a couple of punks trying for open cars in the grocery store parking lot a few weeks ago.

[CallMePuff]

What started this whole adventure anyway? The interior lights coming on at night?
Not sure how you noticed this but lifting the door handle will turn the lights on. Perhaps some potential thieves in your neighborhood?
I caught a couple of punks trying for open cars in the grocery store parking lot a few weeks ago.

Well, if I'd leave the car for a few days and tried to start it, it'd be dead.

Then my family said they noticed the lights randomly being on. I would sure hope it wasn't thieves, but that is a possibility.

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[ross1]

Well, if I'd leave the car for a few days and tried to start it, it'd be dead.

Then my family said they noticed the lights randomly being on. I would sure hope it wasn't thieves, but that is a possibility.

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Have you considered checking the health of the battery?

[CallMePuff]

Have you considered checking the health of the battery?

Sorry, forgot to mention initially that I did have it checked and was shown to be in good health, although that was about a year ago. The battery-dying issue was still occurring at that time despite where we took the battery to test saying it was alright.

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[shogun]

a total of 43 mA is normal, or is there more than 43mA on fuse 20?. If the battery check was a year ago, check it again, but with a load tester, just to use a voltmeter is not a real test, it must be tested under load.
At HF you get a cheap load tester for $21.99 https://www.harborfreight.com/100-am...ter-61747.html

[CallMePuff]

43 mA is normal. If the battery check was a year ago, check it again, but with a load tester, just to use a voltmeter is not a real test, it must be tested under load.
At HF you get a cheap load tester for $21.99 https://www.harborfreight.com/100-am...ter-61747.html

Yeah, it was tested under load last year. I'll have it tested again now and see what it comes back with.

Thanks for the tips!

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