Fuse #5 keeps blowing...

[Hornswoggler]

Hello all!

I have a 1991 535i 5-speed I call Sinbad.

I am having a problem and could really use some help. If anybody here has ideas on my electrical problem, PLEASE post! I have the E34 Bentley manual, and the schematics are very nice... except I do not know the wire routing and don't want to tear up the entire car when it might be much easier to do a spot check somewhere.

My fuse #5 keeps blowing whenever I turn the parking or headlights on. Once the fuse blows (or is removed completely, as it is now), I get the following symptoms:

- Instrument illumination (console/dash lights) is out
- Passenger side parking lights are out
- Error message on OBC display that says "Parking Light +" and another error message

Things I have already tried:
- Have replaced the headlight switch (and fuse again) with no success
- When headlight switch is in the Park or Headlight position, I measure 12.4 V across fuse 5 socket.
- Disconnected some of the load (right front parking light, right rear parking light, interior light dimmer, LCM or lamp control module) and get same readings.
- Disconnected headlight switch and jumping RED/BLUE coming into switch to GRY/YEL and still measure 12.4V. Jumped red/blue to GRY/BLK and still measure 12.4V.

My questions:
- Is there any more load that I am missing or needs disconnected? The GRY/BLK wire goes to the Interior Lights system, which seems pretty complex. If I have disconnected all the load, then I would want to trace GRY/YEL and GRY/BLK along a common path where they might both be severed and shorted to ground. My gut feeling tells me there might be more load on GRY/BLK that needs disconnected.
- Anybody seen this before? :)
- What are some common junction points for the GRY/BLK wire? Some I can disconnect and test to try and isolate the source of the problem.
- Do I really have to remove the steering wheel and dash to dig deeper? I would like to be 80% sure the problem is in that area before that time consuming task. Trying to avoid any wild goose chases if possible.

Any help is much appreciated! If you guys have some suggestions or tests, I can check it out. TIA!

[Javier]

feeds a Gray/Brown wire, and a Gray/Brown/Yellow wire that run trough the Trunk Hinge Harness.

Do a search under Hinge Harness and you will find plenty of information on this miserable bug on E34's.

Javier

Edit: An easy check is to remove LKM to verify if bug is related to Lamp circuits after LKM (like trunk hinge).

[Hornswoggler]

LKM = lamp control module, right? I have removed that already and still getting a short.

I also checked that hinge the other day by taking off the plastic covering and looking at the wires. They look great but I'll also do a search to get more description on what I am looking for.

Thanks!

[SnakeyesTx]

I'd start simple and look for a wire touching frame or body. My friend was fighting blown fuses for a month and when I found out his car was hit in the front, I discovered that his horn wires were crushed and exposed and arcing on the frame shorting his light circuit and bang... no horn or tail lights. Little electrical tape and the car's 15th or 16th fuse since I got there, and he has lights and a horn! Whodathunkit? :D

[Hornswoggler]

removing the LMK, disconnecting right sidemarker bulb/connector, and disconnecting the rear right tail light, and did another measurement.

Took DC voltage from the fuse 5 socket to Gray/yellow wire connector for the headlight switch (switch removed), and still read 12.4V across it. I suspect that GRY/YEL wire is grounding somewhere.

Anybody know where this wire snakes around? Hopefully I don't have to take the car all apart but will do it if I have to. ugh.

[Hornswoggler]

I think thats probably whats going on... just gotta find it! haha

[Javier]

LKM pins 7, 27, and to rear and front right side markers. Splice X245 is in the front harness between the Light switch and the LKM, one wire in, four wires out. Gray/Yellow wire for the rear right marker, also goes trough connector X13 (21 pin white connector below driver's foot rest).

Javier

Edit: If you removed both right side markers and the LKM and still get continuity to ground on Light switch Gray/Yellow wire, no doubt you have a short to ground in the Gray/Yellow wire system coming out of Light Switch. You may select to replace all this wire system together running alternate cables (first unplug X13 below foot rest to discard a fault in the rear side marker cable itself, from X13 to the bulb).

[Javier]

Put and blown a new fuse? To measure voltage across F5 and find 12V does not mean there is a short there until you are positively sure all load was removed.

You can also test across F5 with a bulb light. If normal brilliance is achieved yes there should be a short. If dimmed, probably remaining load.

Javier

[Hornswoggler]

I do have a few more fuses... so I can try that.

I have been measuring the same 12.4V across F5 both with and without the LKM. Whatever a bulb light can detect, a multimeter should be able to read as well, right? (I would expect a lower voltage to result in dim bulb light. Just working with what I have)

[Hornswoggler]

So removing the driver side foot-rest (dead pedal, left of clutch, right?) and I will find X13. That will help a bunch, thanks!

X245... which side of the firewall is that? Deciding to tear out the interior dash or if I need to take out the fuse box to find it.

Thanks for the help! Much appreciated!

[Hornswoggler]

Alright, more info.

I disconnected X13 (atleast I think it was x13... a big white connector under dead pedal), tried again, and blew another fuse.

One thing I did notice, is that the hood light went out with it, which was not on the bentley schematic for the 1991, but is under F5 (GRY/BLK) on the 93+ models. Could not find it anywhere for the 1991. I removed teh bulb and did a few quick tests...

From fuse socket 5 to either end of the hood light socket, I got 12.5V. I then disconnected the ground strap from hood to chassis and got a different reading... 12.5V from one end, and 11.0V from the other. Things changed, but not sure what all that means. If I had more fuses, I would try another, haha.

Does that give any ideas?

[Javier]

very high impedance so being not comparable to any load in the car, will always read around 12 volts no mater if ground trough a short or a load. Instead of measuring voltage across F5, try to get readings of ohms from suspected circuits to ground.

Javier

[Javier]

the Gray/Black wire in the light switch also in 1991. Different light contact than the Gray/Yellow, but share inside light switch a connection to F5.

If you got connection to ground from Gray/Yellow wire being disconnected from light switch, and being LKM and marker bulbs removed, think you are in the right pad. You can remove Gray/Yellow wire from the light switch and connect all together again. If tuning on light does not blow the fuse, bing X13 (white 21 pins) removed, then your issue is in the Gray/Yellow wire portion of wire going to LKM or Front marker. I would first explore the Gray/Yellow wire going to the front marker, it is more prone to short to ground that the harness under the dash and the LKM.

From fuse socket 5 to either end of the hood light socket, I got 12.5V. I then disconnected the ground strap from hood to chassis and got a different reading... 12.5V from one end, and 11.0V from the other. Things changed, but not sure what all that means. If I had more fuses, I would try another, haha.

If 11V with bulb plugged, you just included the bulb load in the circuit, but still grounding trough a short, guess you were working with light switch on, though the rest of the load connected to the Gray/Black wire is also a very low impedance. This test means nothing to your quest.

Javier

[Hornswoggler]

Thought I was getting somewere just a minute ago. I disconnected more of the load from the GRY/BLK wire (sunroof switch, vanity mirror lights, and interior dimmer had been disconnected) and was able to keep fuse 5 alive for minutes without blowing.

Slowly I started reconnecting things, testing inbetween each step. Once I plugged in the door chime (above the pedals), the fuse blew again. Maybe it is just a matter of time until it goes (it doesnt blow immediately) as I am now stumped since the door chime shouldn't have anything to do with fuse #5. weird.

Oh well. Off to buy more fuses and continue tinkering with it.

[Javier]

may be I did not understand what you meant here.

removing the LMK, disconnecting right sidemarker bulb/connector, and disconnecting the rear right tail light, and did another measurement.

Took DC voltage from the fuse 5 socket to Gray/yellow wire connector for the headlight switch (switch removed), and still read 12.4V across it. I suspect that GRY/YEL wire is grounding somewhere.

Be sure that messing around the chime did not moved the wires and caused the short to be back blowing the fuse.

Think you need to remove Gray/Black wire from the light switch and test the system without this cable (all the rest connected), if fuse blows, or test bulb light across the fuse socket light up normally, it is the Gray/Yellow system. If not, go back again to the trunk hinge harness and check it extensively.

To pull out a wire from its connector, you can use the thin wall tubing of a telescopic antenna from an old radio, or home wireless phone. Select tube section which diameter fits in the connector so that the connector pin socket gets in the tubing. It will push back the locks, allowing the wire with its terminal socket to be pulled out from the wire side of the connector. I have an AMP tool for doing this, but guess it is not necessary to buy one.

Javier

Edit: This picture may help understand the procedure.

[Bill R.]

.
Thought I was getting somewere just a minute ago. I disconnected more of the load from the GRY/BLK wire (sunroof switch, vanity mirror lights, and interior dimmer had been disconnected) and was able to keep fuse 5 alive for minutes without blowing.

Slowly I started reconnecting things, testing inbetween each step. Once I plugged in the door chime (above the pedals), the fuse blew again. Maybe it is just a matter of time until it goes (it doesnt blow immediately) as I am now stumped since the door chime shouldn't have anything to do with fuse #5. weird.

Oh well. Off to buy more fuses and continue tinkering with it.

[Hornswoggler]

I did quite a bit of troubleshooting today. So far, with the chime disconnected, I have not blown any fuses. I did pick up some new fuses, so I might plug the chime back in just to verify it is the cause of the problem.

Since the chime is not directly related to the F5 circuit, I am at a loss for explaination. Maybe I did jiggle something around, I don't know. Another possibility is that the chime is what breaks the camels back. Maybe the wires get crossed somewhere else? (i.e. fuse 5 circuit melted onto chime circuit.. sounds crazy but I guess possible)

Tomorrow I'll reconnect the chime to see if the fuse blows. It did it once, now I need to confirm if it is repeatable.

[Hornswoggler]

Thanks for the chart

Do you know which fuse powers the chime?

[Bill R.]

here.





Thanks for the chart

Do you know which fuse powers the chime?

[Javier]

trough the light switch, two separated contacts feed together from F5, runs power to:

- Gray/Yellow wire for right side markers and "LKM feed trough" right Park and Tail lights, if you removed both side markers, lights switch, and LKM; and still got connection to ground at the Gray/Yellow wire, there is the "Illegal connection to ground"

- Gray/Black wire system feeding must of interior indication lights (including power socked light in glove box), License plate lights feed trough LKM, and underhood light. If Gray/Yellow wire is OK, illegal connection is at the Gray/Black and must possible cause is the trunk hinge, some times, the damage is concealed below the tray and not the hinge itself.

The wires melted together is a possibility, but in that case, I doubt plugging in the chime would blow the fuse. if short is to grounding wire, it is there no mater the chime is out, if short is to feeding wire, you plug the load with he chime and not a short.

Javier

[Hornswoggler]

When I got the short on gray/yellow, I had not removed a sidemarker light (just the right front parking light, not realizing the side marker was illuminated... thought it was just a reflector). Disconnecting that bulb, I think gray/yellow is fine.

To test which circuit is causing the overload, I can remove the light switch and jump blue/red wire to either gray/yellow or gray/black and see which one blows the fuse next time (assuming I cannot repeat the chime causing the problem).

Going to drive to work today with headlights on to give it a long test. Will mess with it more tonight.

Thanks again for everybody's help!

[Javier]

unplug LKM and see if it remains there (the short). If so, no doubt it is the License Plate system, as it is the only one Gray/Black going through LKM.

Javier

[Hornswoggler]

So far today I have been driving around (~40 minutes of seat time) with the chime disconnected and headlights on, no problem yet. (/me crosses fingers)

[Hallmark]

I've been tracing a fuse problem involving the same lights for almost a year now. As I read this post it occurs to me that I don't recall hearing the chime when the fuse is blown.

[Hornswoggler]

I plugged the chime in last night to see if the fuse would blow... but it didn't. All my lights are working now so hopefully I somehow fixed it in all that disconnecting, checking, and reconnecting the load.

The chime is above the pedals. Remove that black cover above gas/brake pedals and its the small connected cylinder that is attached to the cover. It didn't make sense to me when I connected it and the fuse blew the first time... so still a mystery if it is involved in the problem or not.

[budshaw]

I had identical problem w/ my "95 525it. Broken wires at the right hatch hinge was the cause. First look, it appeared fine. Upon manually squeezing the harnesses I finally noticed the obvious break. From that point it was an easy fix.

[dgarlits]

This was the fix for mine:

Remove the inside trim (and tool box) from the trunk lid to give access to wiring. Remove the plastic protector from the left side trunk lid arm. Examine all wires for wear points and/or damaged insulation.

Make necessary repairs to all wires. Hope this helps, good luck.