Reversing lights stay on

[hatman]

The reversing lights on my S4 have now decided that they prefer to stay on all the time. I am assuming that it's a case of a sticking switch and, if so, my first problem is gaining access to it.

I've been underneath and identified the two wires from the switch, which appears to be on top of the gearbox; it's certainly inaccessible from beneath the car. Removal of the gearlever and a subsequent squint down the hole took me no further forward as I could see neither switch nor wires from that viewpoint.

Questions then: - 1) Is my diagnosis likely to be correct? (ie sticking switch); 2) How do I get at it? 3) Is it likely to be free-upable or will I need to replace? 4) Is the switch actually inside the gearbox or (as I've been assuming) attached to the outside of the box?

All input gladly and gratefully received.

[john.p.clegg]

The switch is top front right of the gearbox,maybe reachable from the engine bay (if you have thin arms) or even underneath (if you have thin arms)
John

[hatman]

Thanks for that, John, it's a helpful start. Er, having groped my way to it from the engine bay, what am I feeling for and likely/hoping to achieve? Does the switch unplug from something, or is there a moving part that I can manipulate to try and free up for instance?

[ppnelan]

The two wires (you can follow them back from the engine bay on my S4) are fixed (don't just pull them!) to a threaded steel part with a hexagon top. It screws into the top RH corner of the geaqrbox, just behind the start (rear) of the bellhousing. There is a locknut that clamps it. If you can slacken off the locknut (sorry I don't know the size), it may screw out by hand if you're lucky.

I can reach (well, touch!) mine from the engine bay - yes, I have thin arms! The engine has a Stromberg head which means there's space to get behind the rear part of the inlet manifold casting. If you have Webers/Dellortos it will be more difficult.

If you haven't done so already, I would put it in & out of reverse a few times to see if you can free it off first. Then, I would disconnect the wires in the engine bay and put a test meter between them, then in & out of reverse again, to make sure the switch is the problem before struggling to remove it.

Best of luck!
Matthew

[john.p.clegg]

On mine the locknut is 9/16 AF and the switch head is 5/16 whit,Best of luck
John

[hatman]

Once again, thanks John. My car has Dell 'Ortos - wouldn't you just know it! Getting an arm through to the box might well be a no-no, but I'll certainly give it a shot. Being optimistic for a moment (and assuming that me arms is thin enough!) am I really going to be able to get spanners on it that way?

A thought that occurred to me was that 'the correct' way to get at it might be via one of the large circular holes in the side of the chassis - what's your view on that? I'm understandably reluctant to start pulling the glued-on carpet off the tunnel if it doesn't do the trick so any previous experience in that regard would be extremely helpful.

I have tried popping the box in and out of reverse, with no improvement being seen and, if it isn't a faulty switch, what else could it be? Any ideas?

Not sure what I'd be looking for with the multimeter across the wires; checking whether or not the switch is actually switching or not I suppose (but don't the lit reversing lights tell me that already?) Anyway, thanks again for all your input - it is appreciated.

[john.p.clegg]

If your car is going in and out of reverse OK and the light stays on it is the switch

John

[ppnelan]

I was thinking it would prudent to make sure that the switch is in fact NOT switching (with a multimeter) before trying to remove it. After all, it could be a couple of wires shorting somewhere instead!
ALWAYS eliminate the EASIEST things first, even though it's usually the most difficult/painful/expensive ones that are the cause....

Although, this could happen where they are attached to the top of the switch itself, as I think the connections are exposed & uninsulated here and run quite close to the top 'arched' cross member of the chassis. They could have been squashed together if they contacted the chassis. You haven't had any severe engine/transmission jolts recently have you ?

Just a (wild) thought....
I'll shut up now!

Good luck!
Matthew

[rgh0]

With a Weber head in an Elan you need to remove the carbs to be able to reach in and remove the reversing switch. At least that was the only way i could find to do it.

Rohan

[hatman]

Matthew - no untoward shock treatment applied to things but, if I can actually reach it, I'll certainly bear in mind the shorting-across possibility.

Rohan - if it's a case of pulling the carbs off I'm afraid that I'll opt instead for life without reversing lights by disconnecting them! Any thoughts about going in via the side holes in the tunnel?

[rgh0]

I tried it from all sides, top, bottom, gear lever etc before pulling the carbs. The hole in the tunnel is to far back and the top brace across the chassis is in the way when coming from the rear.

Pulling the carbs is not all that hard especially with a cut off 1/2 inch open ended spanner to get at the lower carb nuts.

You could try pulling the engine mounts, dropping the engine down and coming in from the top but that is as much work as pulling the carbs. You could also try pulling the starter and coming up from there, I never tried that, may be possible, but you would also need to pull the mechaincal fuel pump if you have one!

Rohan

[hatman]

Wow! It's looking more and more like a bulbs-out job!