3 replies to this topic

[mullet]

Hi all,

 

I couldn't find the same issue posted before.  So here goes....

 

The lightswitch does not turn on the front 'side lights' (I think they are called (switch half depressed)), nor the back lights.  When the switch is pressed fully (2 clicks) the main headlights do come on, but again the back ones stay off.

 

Mini Mayfair, 1000cc, 1984.  Haynes wiring diagram seems to match wiring diagram #16, but I am not great at reading these. 

 

It seems the 7/8 fuse works and I do get a not-entirely-steady 10volts if I bridge the fuse with a multimeter with the switch pressed fully (2 clicks, main headlights on).  I think it is the 7/8 fuse that also runs the lights I have the issue with.  There appears to be no visible fuse damage in box or visible in-line fuses.  Wiring appears all original.  Bulbs are fine.

 

Absolutely no power reaches back red/green wire that should supply power.  Other lights (brake, reverse, indicator) do work, so earth seems fine.  Front not tested because rear was easier to test.

 

So the supply is broken somewhere.  What other tests could I try to trace it?  The switch has blue, red and brown wires running to it.  Should I use a multimeter on these to earth (if so, which colour would give me a reading to help know if brake is prior to, or after, the switch?)

 

Only thing done recently were new panels wielded on by garage.  These were side panels under their car (long panel where jack hole is).  But not sure any cables run there(?) and even if disrupted in that area, why affect the front?

 

Thanks for any advice!

[lsto]

If the headlight is working then you should have power to the switch. The power to the switch comes off fuse 3/4 and is a brown wire. The power then goes from the switch to fuse 7/8. Put the sidelights on and check both sides of this fuse for power, ie one probe on one side of the fuse and the other probe to an earth. Then repeat on the other side of the fuse, you should get roughly battery voltage each side if the fuse is good.
If you are putting the meter across the fuse and getting 10v it sounds like your fuse is blown.
Try taking the fuse out and checking it for continuity, you may find it's blown.
Also check the terminals on and the wires too the fuse box as the connectors are prone to corrosion.
If you are not getting power to fuse 7/8 on the red wire it may be your headlamp switch has failed.
Good luck.

Edited by lsto, Yesterday, 06:39 PM.

[sonscar]

Conect the wires together at the switch,they are known to melt inside it.One of the terminals can appear to be low or leaning.Steve..

[Ethel]

The supply to the switch may come off the fuse box but it doesn't go through the fuse. As already said it will be good if the headlights are working. 

 

At the lightswitch the brown should be a permanent 12v supply. When you flick the switch to the middle position it connects the  brown to the red, the red then supplies the fuse box where it turns into a red/green wire. The red green supplies the dash illumination, front & rear side/tail lights. There are 2 junctions in the wiring where the dash illum splits off then it splits for the front & rear.

 

(flicking the switch to the 2nd position connects all 3 terminals together, the blue wire then supplies the stalk on the steering column for the headlights.)

 

Tests you can try:

 

Pull the light switch out, to access its connector, so you can bridge the brown & red wires in the connector, eliminating the switch.

 

Check if the instruments are illuminating, if they are it must be a wiring fault beyond where they split of the circuit

 

....if there's no instrument illumination either

 

Confirm the connections at the fuse box are good. You could test the fuse by swapping it with the fuse between the brown & purple wires. BUT be sure it's only powering the interior light as a means of showing it's not blown (broken) - certainly not the headlight flasher!

 

The fuse boxes can get unreliable - removing the red & red/ green wires & connecting them together directly, preferably with the fuse held in the middle should show up any issues there ...if you can hold the wires, fuse and still manage to see the side lights!

 

A wiring diagram