Reverse Lamp Gearbox Switch

[LaikaTheDog]

Hi,

For a couple of weeks now I have had a repeated fuse blow upon ignition.

After two solid days of testing , including a complete dash rewire I eventually traced the problem to the switch for the reverse lamp, it sits on top of the gearbox in a really inaccesible place, when wired up it causes the ignition circuit fuse to blow. I have run a multimeter across it, the switch works, but it appears to have one wire (the Brown and black) going to earth, I guess it is not meant to do this !

can someone confirm that the wire to earth is a problem, and if so , the best way to get the **** switch off the top of the gearbox. My manual makes no reference to this switch as far as I can find, even in the gearbox diagrams it is missing.

4 speed Plus 2 by the way...

Laika

[clemf]

Laika,

The switch is held on by a locking nut that needs to be released and it then unscrews. If you cant get your hand to it from underneath then I think the only way will be to remove the center console and go down through the hole by the gear stick. I'll check my wiring diagram tomorrow about the earth, unless someone else has the answer by then.

[clemf]

Laika,

another thought, be carefull if you take it off. There is a connector about 10cm along the cable, disconnect this first or you might break the wire. I know as I did it !


Clem

[LaikaTheDog]

clemf,

I answered my own question just now, it is definitely not meant to earth to the box itself, I just went through the diagrams and checked the length of the circuit aswell for relays, and then performed some multimeter and test lamps on it, it is definitely busted.

you mention a cable, do you mean the cable from the top of the switch to the wiring loom , or is there some cleverness inside the box ? I have checked this wire from the loom, and replaced it where it had got brittle, hoping to fix the problem with no result.

guess I will have to get my daughter interested in cars...she has dinky hands made for the job...

[TomR]

I had a similar problem on an S4SE and found that it was not the switch itself, but rather the reverse light fixture that was shorted. The copper support for one end of the lamp passes through an uninsulated hole in the lamp housing. The copper was bent and touching the housing. This in turn caused the two bundled wires going to the reverse switch to melt together so the switch appeared to be at fault. May not be your issue but it is probably worth checking.

Tom

[clemf]

Laika,

Yes the cable on top of the switch.

Clem

[LaikaTheDog]

thanks everyone for your input,

I have now fixed it and found the following along the way;
the switch is right at the top of the gearbox and as clemf says it has a lock nut, but the gearbox case around the switch is slightly recessed making it really difficult to get to the lock nut.

To get a good grip on the nut I dug out a spanner with a short handle (3 inches) which meant I could tip it up over the recess lip to get to the lock nut , I found that I had to get the car at least two foot up as two hands are needed to get some leverage, one on either side of the gearbox which means you need to lie right under it ! (maybe I need to loose weight !)

once the switch was off I found the problem; the switch top appears to have bumped repeatedly on the fibreglass of the body above the gearbox, so much so that the fibreglass is now just soft matting, but along the way the two contacts at the top of the switch had bent down until eventually they had touched on the brass nut of the switch mounting, everytime I put the car in reverse I shorted the circuit to ground and blew the fuse.

In the process of removing the switch I broke off the wiring to it as both wires had got very brittle, luckily the wires are soldered to the switch, so not difficult to fix, I put an extra long covered pair to the siwtch so that the connectors are now under the dash and not above the gearbox.

all fixed now