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Old 11-06-2016, 08:53 AM   #1
mohmoh62
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fuse 4 shorting

Fuse 4 is blowing as soon as I turn the key to accessory on in my 87 325is. I've removed the hazard switch and it still pops, so I'm guessing that means the active check control system is where the short is? Anyone have any ideas on where to start? The check panel has a few lights always on because the sensors have been removed (i.e. washer fluid, aftermarket oil pressure gauge etc). The only one that doesn't make sense is the brake light check; the brake lights work fine.

Before I took the switch out, the hazards would work on the driver front and both rear blinkers, but not the passenger front, despite the running light and side marker being lit up with the lights turned on. Blinkers dont work because fuse 4 is popping before I can try it. I put new side marker bulbs in and both the dual filament bulbs in the front (running light / blinker) look brand new.

Edit: Forgot to mention, the blinker relay clicks and works when the hazards flash so I'm assuming that's not the problem.
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Old 11-06-2016, 09:08 AM   #2
Das Delfin
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as you know, dual filament means the light bulb has a low wattage for the parking lights and a higher wattage for the turn signals. This means the bulb is fed by three wires (hot for parking lights, hot for turn signals, and ground). So your turn signal is a separate circuit from your parking light (though they share a ground).

Since your turn signal isn't working, there may be a problem with the turn signal circuit. And it may have something to do with your short. It could be as easy as a messed up bulb socket or its connector. You need to get in there and check it out.

You're gonna wanna download the ETM and figure out how the signal path for the turn signal works. Then get out a multimeter and check for voltage across the line. Look for anything that might distrupt the signal

The ETM has troubleshooting solutions and may have your problem spelled out with an easy way to solve it
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Old 12-11-2016, 09:07 AM   #3
mohmoh62
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I checked the ETM and Bentley. ETM only and wiring diagrams and bentley only had a troubleshooting section for flasher relay.

I bought a tone generator and probed the fuse 4 circuit throughout most of the car. I opened up the wire harness loom along the entire driver side and followed the violet striped wire. It makes a tone all the way to where some connector was at the passenger side near the headlight.
Tone can be heard at the active check control unit and seat belt wire under driver seat. I stopped following it after it went into trunk.

That having been said, the hazard switch wires didn't give a tone with it plugged in and pressed or unplugged, but the defroster next to it did when it wasnt on / pressed (maybe the wire passed nearby?). None of the blinker wires / connectors gave a tone and the circuit still shows short to ground on each blinker connector.

Blinkers worked OK until I fixed the fuse 10 short problem by removing the seat belt timer relay, or at least that's when I noticed.

Any ideas?
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Old 12-22-2016, 04:17 PM   #4
RobDog
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Maybe the glove box light or glove box flashlight. I have read somewhere that they are wired to fuse 4 on some models?
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Old 01-01-2017, 10:32 AM   #5
mohmoh62
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Quote:
Originally Posted by RobDog View Post
Maybe the glove box light or glove box flashlight. I have read somewhere that they are wired to fuse 4 on some models?
I checked the glove box light. It was connected but the bulb was blown and I don't recall it ever working in the time I've owned the car. Haven't had time to mess with it since the last post, but going to troubleshoot more tomorrow
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Old 01-10-2017, 07:15 PM   #6
mohmoh62
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I checked glove box light and flash light connector. Both are fine/not shorting to ground. I did notice after rereading the etm that the wire I'm getting a tone on for fuse 4 in engine bay is violet with a black, maybe gray stripe. ETM says it should be violet with gray stripe, but going to connector 103 under LH side dash and then on to hazard switch and active check control. However, my wire goes from fuse box to front blinkers. Is that correct?

Anyone have any ideas? I'm about ready to burn this thing
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Old 01-10-2017, 07:19 PM   #7
ScottSneed
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http://www.e30zone.net/e30zonewiki/i...iring_Diagrams

Check this out..I had a similar issue with my interior lights, kept blowing a fuse. Ended up being a faulty headlight/foglight switch.
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Old 01-11-2017, 02:55 PM   #8
RobDog
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Ether D was shorting fuse 4 and it was because of smashed wires to the brake lights under the drivers seat.
http://www.r3vlimited.com/board/showthread.php?t=386838

Info from E30zone:

*Indicators:
Bulb: 12V 21W

The orange bits at each corner of your car are there to signal your intentions to other road users. They are called Indicators, and are operated by a column stalk switch and are controlled by a flasher relay located under the lower half of the steering column shroud, just behind the steering wheel. In typical fashion, if a bulb blows then the indicator on that side will flash twice as fast as before.

Wire colours are blue/red and blue/black, with brown earths. These lights also form part of the hazards circuit, and therefore all the wires go through the Hazard light switch on their way to the lamps.

If all of your indicators stop working, then check the Hazard switch, and ensure that it is plugged in correctly. It's also worth looking at the glove box switch

*Glove Box:
Bulb: 12V 4W capless (RHD) 12V 5W Festoon (LHD)

The glovebox light is a bit of an oddity on E30s, and seems to have been an afterthought for the interior designers.

There are two distinct versions in use, but either can be fitted with the right knowlege. LHD models have a separate light with a push-in switch mounted to the glovebox catch, RHD models have a combined switch/light with an exposed bulb.

Early facelift cars have the light on a permanently live supply from fuse 21. Later cars have an ignition switched feed from fuse 4, but the handbook was never updated.

If the RHD version of the switch/light is left without a bulb fitted, or, if the feed wires are connected the wrong way around, the unit is knocked askew, a short circuit will often occur, leading to issues with the indicators.
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Old 01-15-2017, 11:30 AM   #9
mohmoh62
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I probed the fuse 4 terminal to the blinker relay power in wire and saw it was shorting. I gave up trying to find the short in that leg of the circuit so I just ran a new power wire to it. Problem solved. Blinkers work again.
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