Headlights & fuses

[ferlin]

So the dreaded headlight problem has finally cursed my wedge. I have one popping up fine the other refusing to lift. A fuse that I cannot identify that just blows straight away and the rear brake light? relay is getting hot! There is obviously a heavy current being pulled somewhere.
Has anyone got a layout of the fuses for a mk1 350i with coloured wiring and the fuses under the ecu panel in the passenger footwell please.
I have removed the offending lift motor and it works great on the bench and is bone dry inside too!
I have cleaned up the blade fuses, wiggled wires, tried to identify relays and now im pretty stumped and looking for ideas!

[wedg1e]

The brake lights don't use a relay....

[jeff m]

wedg1e said:

The brake lights don't use a relay....

Out on a limb here, and not trying to be a smart arse but some cars do have a brake light relays that operates brake light failure indicator lamps on dash. I'm not sure if the 350 has these. (I don't have a 350.)

Anyway for a start pull out the relay test across the two pairs of contacts one pair should be over 80 ohms the other should be open circuit (infinity), if in doubt buy a new relay.
Check if fuse blows with the suspect hot relay not in circuit.

If it is the brake light fuse, start faulting by the removing bulbs and checking brake switch.

[njhucker]

Try changing the lift motors over, just to finally rule out the motor. I have had to replace 2 of mine in 4 years, and
although they worked out of the car & I soldered all of the joints could stiil not get them to work in the car. Also if i remember corectly, there are wires which are tight up against the frame when the motor is screwed in and it may be possible that these hare shorting.

[ferlin]

thanks for the advise so far. I will investigate more deeply!
Does anyone have a decent and accurate layout of the fuses and relays though as mine dont bear any resemblance to the bible. I thought I had nearly cracked the relay layout apart from a coupke but there was definately one that stopped the brake lights from working when it was removed!

[wedg1e]

There are one or two relays which only operate when the ignition is turned on: they supply power to all the circuits that only work when the key is turned. I can't recall if the brake lights are fed from there, but it would certainly explain why pulling the relay kills the lights!
Also, these 'ignition' relays tend to get warm due to the amount of current taken by the ignition coil, heater fan, stereo etc...