Head light issue

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sag
E30 Zone Regular
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Posts: 319
Joined: Tue Jan 08, 2008 11:00 pm
Location: London

Sun Dec 22, 2019 8:08 pm

Wiring guru's

Finally got my other E30 back , which has been converted to a M30 turbo, will be taking it to the workshop NX week for various issues and checks

First issue

Havin issues with headlights... when position light are on the headlights turn on

On low beam relay pin 85 is earthed for the relay to power on .. for some reason when position lights are put on,pin 85 is earthed and the headlights turn on

Probing the light switch connection YL/GN wire is always live, even with the connection off. As soon as i put it on dipped beam,the wire turns to earth( which to me the light switch is working correctly IMO).. when the light switch is put on to position lights the YL/GN wire is still live but on low beam relay pin 85 has earthed and powerd on the relay

To me it looks like the position light circuit is some how earthing pin 85(low beam relay)

Also on the second picture what are them two relays for(behind the glove box)? Its something to do with the lights,As when i remove them the YL/GN wire looses its constant Live.. but still when the position lights are put on , pin 85 earths and powers on the H/lamps, even with them two relays removed.

Might be related to the above issue... on the third and fourth picture.. when i got the car back the fused wire had melted/burnt out, the guy bridged the wire as a temporary fix, but it was still melting(4thpic) what i noticed was the the main fuse box wire was connected to that fused wire and according to the wiring diagrams it should be connected to main battery wire, i swapped the wire to the main battery wire and cut out the DIY repair and put in a inline fuse(pic5), so far that circuit seems to be ok, its not gettin hot or blowing the fuse out.

Just Hoping no fuse box issue.. but it could be quite possible the above issue might have caused a fuse box issue and in turn causing the head light issue.

Any pointers on what to check Next?? Or is it question of splitting the fuse box, is there a guide for it?

TIA

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Brianmoooore
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Sun Dec 22, 2019 8:39 pm

First of all, published wiring diagrams are likely to be for US spec. cars, and there are several differences in the headlamp and fog lamp circuits when compared to the wiring on UK cars.
The two orange relays in your second pic. are examples of the circuitry that I've never seen in a published wiring diagram, since they were fitted to UK spec. cars for a couple of years only, around '88 on, in anticipation of some new lighting regulations that never happened. They are part of the dim dip driving lamp arrangements, which ensures that you cannot drive with just parking lights on - similar to the driving lights which are always on on new cars nowadays.
If you pull the lighting switch to the first position with the engine off, just the parking, tail lamps, instrument and number plate lamps should light. If you start the engine, the dipped beams should light, but at reduced brightness. The reduced brightness is caused by two high wattage resistors (fitted right at the front of the LH inner wing), connected in series with each dipped beam lamp's filament. When you pull the lighting switch fully out, the two orange relays short out the resistors, so that the dipped beams come up to full power.
Is this what is happening with your car? If so, it's behaving exactly as designed.
Re, your blown fusible link, the only thing that should be connected to the terminal on the bulkhead that's fed by that link is the engine ECU. Starter motor, fuse box and ABS pump should all be connected to the other terminal fed by the much larger wire.
sag
E30 Zone Regular
E30 Zone Regular
Posts: 319
Joined: Tue Jan 08, 2008 11:00 pm
Location: London

Sun Dec 22, 2019 8:55 pm

Mr Moore the messiah 😎👍

The headlights are off at the moment... but did recall when the head lamps were connected that the dip beam was dim on parking lights on and brighting up on dip head lamps where put on... Hopefully thats sorted, will comfirm once i put the lights back

Yh the fused Bat wire is connected correctly Now. Was drawing too much current, Hence why the fused blow out and the temp repair was melting

Thanks for your help bud😁
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