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Problems with the reverse lights

Postby Frank Labruier » 17 Jul 2017 11:46

The reverse lights on my RV8 turn themselves on if the car is driven for at least 30 minutes in hot weather. They go out again when I cut the ignition or when the car cools down. Repeatedly engaging or disengaging the reverse gear doesn’t solve the problem. When I use the car on cold days it doesn’t happen. So the malfunction is definitively related to heat. Does anyone have any ideas how to fix the problem ?
Frank Labruier
Posts: 2
Joined: 03 Jan 2013 12:51
Location: Luxembourg / Europe

Re: Problems with the reverse lights

Postby John Hale » 17 Jul 2017 19:59

Hello Frank
I'll try to help, the reverse lights are powered from a live feed from the fusebox on a green wire to the reverse lamp switch which is on the top of the gearbox, when the switch is closed (reverse selected) the power goes to the reverse lamps on one then to two green/brown wires. There's a multi pin plug on each tail lamp which carries the power on to the bulbs and then back through the plug down to earth through two separate earth header joints (left and right).

So how could power be getting to the bulbs? 1) most likely for me is a faulty switch or 2) a short caused by pinched switch wires (that is the green and green/brown) under the tunnel or after they come back into the car (through a grommet in front of the handbrake) before being separated or 3) an earth return leakage.

3) can be ruled out by removing both tail lamp connectors when you have the fault and see if there is power on either of the green/brown wires, if powered then it must be fault 1) or 2). If no power it could be earth leakage but I can't see why/how, normally you would clean and grease the two earth contacts in the boot.

To determine between 1) and 2) disconnect the switch under the tunnel but not when it is hot (you may need a pre teenage child with small hands) run the car as when you get the fault: no lights its 1), lights as before and you'll have to trace the switch harness carefully.

With any luck you may get a better simpler suggestion from one of our members on here, the teenage child comment was a joke and no children were harmed in the making of this post, good luck. John H.
John Hale
Posts: 40
Joined: 06 May 2015 11:49
Location: Stratford, Warwickshire.

Re: Problems with the reverse lights

Postby Richard Withington » 18 Jul 2017 07:28

There is an earlier post on the BB around January 2015 which may be useful. Basically the switch on the gearbox is adjustable and it may be that a minor adjustment will cure the problem. I have not had experience of this but suspect this may help, unfortunately I understand it is difficult to access.
Richard Withington
Posts: 37
Joined: 18 Dec 2012 08:28
Location: Grantham Lincs.

Re: Problems with the reverse lights

Postby Nic Houslip » 20 Jul 2017 15:24

I think Richard's suggestion is most likely to be the solution. The switch on the selector housing is adjustable and the increase in temperature there could cause something to expand and cause switch to make contact. There are detailed instructions on how to adjust the switch in the Workshop manual AKM7153EN. It looks like a least a 2 cups of tea job to me. If you happen to have the engine and gearbox out it is much easier :-) B & G have the manual in stock, on CD, makes great bedtime reading. I have an RV8 gearbox [LT77] out of car at the moment and can send a picture if you wish.
Nic Houslip
Posts: 48
Joined: 18 Oct 2013 13:06

Re: Problems with the reverse lights

Postby Frank Labruier » 20 Jul 2017 17:25

Thanks a lot to John, Richard and Nic for your very much appreciated help.
As my mechanical skill are VERY limited, a couple of photos would be great. But I think that my RV8 (N°1984) is fitted with the R380 gearbox. Is there a big difference concerning the switch between LT77 an R380 ?
Frank Labruier
Posts: 2
Joined: 03 Jan 2013 12:51
Location: Luxembourg / Europe

Re: Problems with the reverse lights

Postby Mike Howlett » 20 Jul 2017 19:10

Frank, it's easy to tell which gearbox you have by the lever position for reverse. On the LT77 the lever has to go left and forwards, up beside 1st gear. On the R380 reverse is found by moving the lever right and back, below 5th gear. On the LT77 the switch for the reverse lights is on the remote housing next to the gear lever socket. On the R380 it is located forward of that on the main gearbox case, or that's what I seem to remember. It's years since I last had my gearbox out of the car.

If you can safely get the car up high enough to lie completely underneath, using a torch you should be able to see the wires and the switch. Whether you can get at them is another matter.
Mike Howlett
Posts: 130
Joined: 15 Dec 2012 09:27

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