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MG MGB Technical - Reverse light problems?

I have a 1966 MGB GT which has a problem with the reverse lights, in htat they dont light up.
i have replaced the bulbs and think that the reverse switch may need replacing.
Does any one have any advice on how to find the problem
and how to fix it.
if it is the reverse switch how do I go about replacing it, it sound simple, but i recon its a job and a half, any help greatly apprecieted
yours GD
g sykes

I know it sounds obvious, but have you checked to see if the lights are plugged in?

Mine have little plugs under the housings in the boot, and they're easily dislodged......... just a thought..

Mike
Michael barnfather

I have exactly the same problem on my roadster. The plugs are a little worn and the first time you put anything in the boot they get knocked off and.... no reversing lights.
steve
Steve Coulson

Check for power at the bulbs first, then work backward from there, checking to insure they are plugged in, checking for power at all connections back to the switch on the transmission. The switch itself is easy to replace, just a bit hard to get to. If you have small hands you should be ok. I replaced mine without removing anything. It's located on the top right of the tranny. What condition are your lenses in? Mine were so cloudy that you couldnt see the light through them.
william fox

GD. William is correct. Start by checking your grounds to make sure you have them and they are good. Then, put the transmission in reverse with the ignition switch in the run position and start checking for power. If possible, get a copy made of the factory wiring diagram in your workshop manual. Have it enlarged when being copied. This makes it much easier to trace wires. Then go through, circuit by circuit, until you find the problem.

Some things to be aware of. When the ignition switch is in the run position, it also provides power to the fuel pump and coil. It may be desirable to disconnect these lines when doing your testing.

Reverse switch is located on the top of the tranny. On most cars, it is possible to drop the rear transmission cross member and get access to the reverse light switch. The area around it will be dirty (at least it has been on every car I have ever worked on). Make sure you clean it as well as you can and get the maximum amount of loose dirt from around it so none can get into the hole it seats in. The switch can fail to work for two reasons--switch failure and out of adjustment. The reverse light switch (same type of switch is also used as the OD and TCSC switches) is the "typical Lucas junk"--I have never seen one go bad unless someone physically struck it and broke it. I have seen one worn out switch, two switches which had been broken while removing the tranny from the car and numerous out of adjustment switches.

If there is power into the switch, but now power out, remove the switch and bench test it. If it tests bad, replace it. If it tests good, install it again and adjust it. It is adjusted through a series of fibre washers, usually either one or two. You want the switch to be able to be turned tightly enough to seat and not jar loose, but not be turned in so much it fails to operate properly.

It might be worth checking the VIN of your car to see if it really is a 66. Back up lights were made standard in late 67 about the time the Mark II was introduced. Mark I cars with back up lights are fairly rare in the 67 model. If you have a 66 with back up lights, you would have a fairly rare option which, to me, would make the car more interesting. Les
Les Bengtson

'lo

My 3-synchro trans didn't have a reversing switch on it, and my dealer-fit reversing lamps (very nice, glass lenses and everything) have a switch on the dash next to the O/D switch. I had thought they were all like this.

I really should get around to putting some new bulbs in them at some point :o)
--
Olly
Oliver Stephenson

Before groping around on top of the gearbox find the green and green/brown wires where the gearbox loom joins the main (green) and rear (green/brown) looms and link the green from the main to the green/brown to the rear. If that lights the lights with the ignition on then you will have to grope. If not check for 12v at the link and that will tell you whether the problem is back towards the fusebox on the green or forward (if you see what I mean) to the lights on the green/brown.
Paul Hunt

This thread was discussed between 23/01/2003 and 24/01/2003

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