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Reversing light questions

1298 Views 11 Replies 5 Participants Last post by  Cosmo
I'm fixing up the wiring for the reversing light and have a couple of problems.

The switch in the gearbox should be a simple on/off type and make the circuit between a yellow/black feed from the side lights and the white wire going to the light itself. Instead I have a switch that grounds both wires when in reverse. Is this just a broken switch? I can't see any reason for having two wires coming from it if it were a switch to ground?

There is no hole in the rear bodywork for the feed for the reversing light to go through. Where is the hole located? I'm guessing it must be just a simple hole, with a grommet, somewhere close to the rear bumper mount.
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:confused: The leads at the switch should have almost zero ohms when in reverse, not ground, but no ohms allowing power to flow through said switch. Don't test to ground, test the two leads going into the switch, when not in reverse, should have infinite ohms, when in reverse, nearly no ohms.
Yup, I know how the switch *should* work - it is normally open circuit, but instead of being closed circuit when in reverse it connects both poles of the switch to ground. Must be a broken switch right? Fixable with a relay, but I would like to know the correct behaviour.

And where is that hole in the rear bodywork?
the switch is broken.
I have a working spare, pm me your address and I'll ship it out to you. Just donate $10 to the board and we'll call it even.
That's a kind offer but it's a long way to here in England and the US Post Office doesn't do surface mail anymore. I think I can work around it with a switching relay but just wanted to confirm that I wasn't imagining things.
Hi Cosmo
Contact Richard or Giles will be happy to help, they do postal which is a bit easier than visiting them in PeckhamRye. On my GTJ it would be a gearbox removal to replace it. You might want to consider what other parts you need at the time. The rear mount is a favourite & the rubber drive doughnut.

Is your 1750 Spider a '69? On all the Spiders that I'm familiar with, the switch is in the bellhousing. Up through '73 they were mounted on a bracket that screws to the top of the bell, after that they used a threaded switch that screws directly into the back of the bellhousing. As crash said, it requires removing the transmission to replace the switch so your relay idea might be a good one if it's a good solid (current capable) connection to ground. Some of the later transmissions have an additional switch in the tower but I think that's just a Neutral position switch for a seat belt interlock (or something).

Mine is a 1968 and the thought of taking the gearbox out just to replace a switch does not appeal. When I looked at the old, burnt wiring I had thought that it had somehow got too close to the exhaust manifold and shorted out that way - now I know what actually happened. Although, when I first hooked it up, it blew the fuse and did not cause wire meltdown.

It seems a pretty solid earth when it switches and only has to run a low current relay so I'll leave it like that for the time being.

Now, unless someone can point out the correct place for the wiring hole in the rear bodywork, I'll have to go driller killer and make a random guess. And how many points will that loose me in front of the judges? :rolleyes:
my gtj is behind the bumper somewhere outta sight! If you really want to be exact I guess an owner will measure for you.
Thank you very much, that's just what I wanted. From that picture it looks like you aren't going to loose any points at all! :):):)
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