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Electrical woes............ :-(

Posted by Flyboy 
June 26, 2012 08:16AM
Hi Flyboy & Ferdiand & All,

This is my first time to the E30 Network.

I did a search for the following problem and it brought up this extract from this forum:

"..........Check the fuse box, sure as nuts, number 10 is blown, pop in a spare and all is good, all lights on, starts right up, driving to work the next day the whole panel dies, tem, fuel tacho, fuel consumption, every thing except the speedo.
Get to work, whip the bonnet open, sure as God made little green apples, #10 fuse, blown........."

I have a 1989 E30 325i Automatic and my car has been giving me the exact same fault (intermitently) Whilst driving the temp gauge and rev counter would stop working and sometimes I will see smoke coming from the under dash area. The car will not start unless I replace the fuse and then a few months later the problem recurrs. My fuses used to blow intially, now they just melt.

Kindly advise what the cure was for your number 10 fuse blowing. Was the fix just the rheostat or something else as my dash lights are all fine.

Looking forward to your help.

Thank you.
June 26, 2012 12:51PM
Not sure if it was on the same fuse, I was once having issues on a previous E30 with a fuse blowing, dash lights went out, turned out to be the rear ash tray light wires being damaged somewhere under the center console.



Edited 1 time(s). Last edit at 06/26/2012 12:51PM by Michiel 318iS.
June 27, 2012 02:23PM
Quote
carrapeza
My fuses used to blow intially, now they just melt...
Kindly advise what the cure was for your number 10 fuse blowing.
Is it only Fuse-10 that's blowing?

Fuses should not be melting! Fuse-10 should be just 7.5 amp. The whole point of having a fuse is that it's the weakest link in the circuit. Any short downstream in the circuit should blow only the inexpensive and easily replaceable fuse, NOT causing smoke from under the dash or melting wires.

Download the wiring diagram for your model year from this link: [shark.armchair.mb.ca]
Start with section 0670 Power Distribution.

0670-0 shows the fusebox layout
0670-1 shows which fuses power which circuits
0670-3 (See left side of the page) When the ignition switch is in the start or run position, Fuse-10 powers the K7 Unloader Relay. If Fuse-10 blows, that means there's no power to the K7 relay, and subsequently no power to either of the circuits through Fuse-19 or Fuse-20 as well.

0670-8 details for Fuse-10. That page shows an overview of the various circuits fed by Fuse-10, with page references for further details.

I've never looked at the wiring for an automatic transmission equipped car, but the most common cause of a blown Fuse-10 is the wiring for the reverse light switch. On the manual transmission there is an electrical switch mounted up on the side of the transmission. The two wires for that switch run from inside the car, down through the shift lever opening in the transmission tunnel. Those wires are subject to chafing and shorting out.
rkj
June 28, 2012 11:16PM
Quote
Ferdinand
Quote
carrapeza
My fuses used to blow intially, now they just melt...
Kindly advise what the cure was for your number 10 fuse blowing.
Is it only Fuse-10 that's blowing?

Fuses should not be melting! Fuse-10 should be just 7.5 amp. The whole point of having a fuse is that it's the weakest link in the circuit. Any short downstream in the circuit should blow only the inexpensive and easily replaceable fuse, NOT causing smoke from under the dash or melting wires.

Download the wiring diagram for your model year from this link: [shark.armchair.mb.ca]
Start with section 0670 Power Distribution.

0670-0 shows the fusebox layout
0670-1 shows which fuses power which circuits
0670-3 (See left side of the page) When the ignition switch is in the start or run position, Fuse-10 powers the K7 Unloader Relay. If Fuse-10 blows, that means there's no power to the K7 relay, and subsequently no power to either of the circuits through Fuse-19 or Fuse-20 as well.

0670-8 details for Fuse-10. That page shows an overview of the various circuits fed by Fuse-10, with page references for further details.

I've never looked at the wiring for an automatic transmission equipped car, but the most common cause of a blown Fuse-10 is the wiring for the reverse light switch. On the manual transmission there is an electrical switch mounted up on the side of the transmission. The two wires for that switch run from inside the car, down through the shift lever opening in the transmission tunnel. Those wires are subject to chafing and shorting out.

I had a weird thing happen to mine (1988 325is/5) that sounds a little like carrapeza's deal. It only happened once and I changed my battery after, and it hasn't happened since (as he knocks on wood). I was at the beach listening and watching the ocean, and I had the radio on low. All of a sudden I got this whiff of smoke from under the dash; a few seconds of real smoke and then nothing. I went to start the car and nothing.... after a tow home I charged the battery and everything was fine, no blown fuses or anything.

I've repeated that beach scene many times since and all seems well, but, what the hell was that smoking all about?:rolleyes:

Cheers, Rick
Hi Ferdinand, Flyboy & Everyone across the Autobahn smiling smiley

I am the original owner of a manual shift 86 325e with under 100K miles. I am so glad after much searching to have found this site, because I keep experiencing the dreaded INTERMITTENT #10 fuse burn out. The only "symptoms" are the loss of tachometer, gas gauge, temp...etc. It's driving me crazy because it's so darn intermittent. It can go for days, almost a week or literally hours. Every time I bring it to my mechanic, it works.., for awhile and I'm beginning to think he may not be the person to diagnose it. Electrical repair here in SF costs a fortune and before I spend more than the car is (financially) worth, I thought with a little help I might be able to tackle it myself.

I've tried to isolate what I'm doing when the fuse burns to see if there's any cause and effect; thought it was the blower but it blows regardless of whether the fan is on or off....I can go 50 miles and boom goes the dynamite...I'm blowing fuses just about every other day now. It blew yesterday at about the same time I hit the horn, but I don't have any fuses left to test THAT theory.

Here's what's strange...I've noticed that when the panel drops out, the tach will come back momentarily on start up...and then again the tach may come back on for 5 seconds or so on it's own while I'm driving (presumably with a blown fuse). Tonight with a fuse blown for several days, I noticed that while parked without engaging reverse, the tachometer came back up every time I applied the brakes and then went back down...I repeated this pattern maybe 5 or 10 times over a few minutes. Brake pedal down...on goes the tach...foot off brake, tach back down...repeat 5X...I was so excited, I didn't notice whether the gas and temp gauges were working too.

Once I started driving no more brake/tachometer interaction...and I never saw that pattern before today...No idea if it will repeat. Any help would be greatly appreciated....I love the car but I need my AIR...Could the horn be interacting....or am I just noticing a non existent pattern. (It always happens only in the daytime except when it doesn't) smiling smiley

Thanks guys!!
Welcome! Electric gremlins can be so annoying to troubleshoot. The first thing I would do is get yourself a wiring diagram from here: http://www.armchair.mb.ca/~dave/BMW/e30/. It says that Fuse 10 controls the following:
  • seatbelt warning
  • service interval indicator
  • tach/fuel economy gauge
  • gauges/indicators
  • brake warning system
  • back-up lights
  • on-board computer
  • idle speed control
  • active check control
  • stop lights/cruise control
That's a lot (which isn't going to make it any easier to troubleshoot)!

The second thing I would do is see if any of those components (starting with the easiest ones) are shorting out anywhere.

I'm sure Ferdinand or Rick (if he ever gets back after Sandy) or others will have more intelligent things to suggest.

__________
Dave
'91 325iX
Quote
Dave_G
Welcome! Electric gremlins can be so annoying to troubleshoot. The first thing I would do is get yourself a wiring diagram from here: http://www.armchair.mb.ca/~dave/BMW/e30/. It says that Fuse 10 controls the following:
  • seatbelt warning
  • service interval indicator
  • tach/fuel economy gauge
  • gauges/indicators
  • brake warning system
  • back-up lights
  • on-board computer
  • idle speed control
  • active check control
  • stop lights/cruise control
That's a lot (which isn't going to make it any easier to troubleshoot)!

The second thing I would do is see if any of those components (starting with the easiest ones) are shorting out anywhere.

I'm sure Ferdinand or Rick (if he ever gets back after Sandy) or others will have more intelligent things to suggest.

Hi Dave,

Thanks for the input...I'm looking over the wiring diagram right now and it makes me wish I had gone to MIT instead of getting a liberal arts degree. I may go spring for a voltmeter...It can't be much worse than the time I bought a few old Tandberg reel to reel tape decks with the intent of using the parts to put together one working deck. It was very easy taking the things apart...but at the end of every "reconstruction" I kept having extra parts left over...reminded me of a meth head who decided to take a television set apart because the picture was fuzzy...
Might want to check that wire that goes to the switch to the trans mission controlling the backup lights. That can get frayed insulation along it and short to ground.

Bob in Everett
That's a good one. Had about the same issue with the dash illumination, turned out the rear ashtray light wiring was touching ground somewhere below the central console.
Quote
Bob in Everett
Might want to check that wire that goes to the switch to the trans mission controlling the backup lights. That can get frayed insulation along it and short to ground.

I think this is the first place you should look. If the wire to the backup light switch isn't properly restrained it can swing around and once in a while it will touch the driveshaft. After that happens a few times the insulation will wear through and then when it touches, it shorts the circuit to ground through the shaft. That's what happened on my car. My original wire clips were long gone, so after I repaired the wire I used wire ties that I didn't pull down tight to hold the backup light wire close to the shift linkage. No more blown fuse 10 since the repair.

John
October 31, 2013 01:59PM
Greetings Ferdinand & Flyboy & all the E30 fans !!!,

I trust you are all well.

Herewith feedback on how the problem was finally resolved. Fuse #10 had not blown for about year , however in March this year my E30 was due for an oil change. I had taken my car to an E30 specialist where I had mentioned in passing about Fuse #10 blowing once in a while. The owner of the garage offered to look for the fault. After stripping the dash it was discovered that some of the wires on the harness to the fuse box had melted. The main wire that was affected was the Green / White wire from the blue block that plugs into the instrument cluster. Some of the neighbouring wires were also slightly affected. Replacing the entire harness on the car was the right option but not a practical one. Luckily we managed to obtain the piece we were looking for from another donor E30 that was being customised for the track. With my car being a right hand drive, this entailed having the entire piece from the instrument cluster to behind the glove box being replaced. This was a mere cut and join (solder) process. The entire repair took four months, understandably the garage had to divert it's resources to other customers whose cars required normal repair work unlike mine. So far I am happy with the end result, unfortunately the fault was not identified during the repair process. My suspicion is that this was caused by poor workmanship when the previous owner had an aftermarket alarm fitted in. In addition to this I had discovered and removed two complex vehicle tracking devices as well, which were installed by previous owner/s.

I tried to attached some pics of the harness that was removed from my car which shows the damage to the wires, unfortunately they were bigger than 500kb. If anyone would like to see these send me your e-mail address and I will gladly forward to you. But I managed to squeeze in a pic of my ride.

Thanks for all the help & advise.

Take Care
Carrapeza
Attachments:
open | download - 184038_106352572799558_2649338_n - Copy.jpg (112.6 KB)
January 20, 2015 11:46AM
Hi Guys, just some feedback, late I know, but better than none.
Yep, wire from the reverse light switch was shorting out where it entered the car at the gear lever tunnel.
May thanks all.

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E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.
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