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Reverse Lights Stuck On


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#1 dunkyb

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Posted 04 March 2020 - 09:44 PM

Hi all,

Hoping someone can point me in the right direction. My ‘98 Mini’s reverse lights are always on (with ignition). I disconnected and removed the reversing light switch on the gear selector housing, yet the lights were still on!

This suggests there’s a short? If so, any clues as how to find it? Haynes manual says fuse C6 circuit is shared with stop lights and reverse lights. Brake lights and everything else seem to work ok.

Tested the switch whilst it was out and also managed to blow the fuse whilst under the car, so definitely power running to the switch. Have tried pulling all fuses one at a time and the reverse bulbs stay on, only when pulling fuse C6 do they go off.

The wiring at the RHS light cluster looks ok to me, but the fuel tank is in the way so can’t see the LHS cluster wiring.

I’m a bit of a novice and this is my first classic mini, only just picked it up and absolutely loving it .. so be kind 😉

Many thanks!!
Duncan

#2 sonscar

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Posted 05 March 2020 - 09:39 AM

Are the wires melted near the exhaust?Cheap easy check.Steve..



#3 dunkyb

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Posted 05 March 2020 - 10:34 AM

Hi Steve,

 

Thanks for the reply.  Would I be checking around the reverse switch wiring do you think, which runs very close to the exhaust?  

I know the wiring from the switch to the bulbs is Green/Brown, but guess something else must have melted onto one of these somewhere feeding it 12V ?

 

Duncan



#4 KTS

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Posted 05 March 2020 - 08:26 PM

if the cables have melted as a result of contacting the exhaust, it should be fairly evident from a visual inspection (after cleaning all the crud off the wires of course)

 

the other possible cause is a short where the wires pass through the floor of the car under the gear lever gaiter - as above, once you've removed the gear lever gaiter to inspect the cables it should be apparent if the issue is there 

 

the reverse switch loom connects to the main loom by a couple of bullet connectors (green for live, green/brown to the rear loom for the reverse lights) )to the rear of the heater unit (cables to the reverse switch usually run from there under the carpet to the gear selector housing) - disconnecting them should disable the reverse light.


Edited by KTS, 05 March 2020 - 08:28 PM.


#5 dunkyb

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Posted 06 March 2020 - 02:34 PM

Thanks very much for that info, really useful! Now I have a good understanding of where the switch wires connect to and run to the reverse lights at the back, now it's just finding where the 12V feed is being introduced. It looks like the carpet has to come up and a few screws removed to get the gaiter off, was rather hoping

that wouldn't be the case haha.



#6 dunkyb

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Posted 22 March 2020 - 10:03 AM

Hi all,
Still struggling to find where the short is.

Does anyone happen to have a picture of where the reverse light switch wires run / connect to at the back of the heater unit so I know what to look for and possible places of chafing?

Many thanks,
Duncan

Edited by dunkyb, 22 March 2020 - 10:05 AM.


#7 KTS

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Posted 22 March 2020 - 10:57 AM

you can see them in this picture - it's from an earlier car to yours, so connectors may have changed,  but as far as i'm aware the cabling should be in the same area

 

 

https://i.imgur.com/VEdb2Q3.jpg



#8 dunkyb

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Posted 22 March 2020 - 11:04 AM

Thanks KTS - So the wires would come up from the gearbox switch through the gear selector hole and connect into those ball connectors at the back? Guess the carpet has to come up then in order to get the gear selector gaiter off and check further?

Thanks a lot

#9 KTS

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Posted 22 March 2020 - 11:16 AM

yep - carpet out will make it a lot easier to see what's going on, and how the wires route through to the switch on the remote selector 



#10 dunkyb

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Posted 22 March 2020 - 05:25 PM

Disconnected the reverse light switch today and probed the green/brown wire, and it has 12V running across it.  (Light screwdriver lit up when probing it with earth connected to chassis).

I expect it'll be around the gear lever selector as that's where the most movement is.

 

What confuses me is why when I put it in the reverse (and the switch connects the two wires together) it doesn't short out, if there's 12V on both the green and green/brown wires?

 

Duncan



#11 KTS

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Posted 22 March 2020 - 10:14 PM

The fuse would only blow if the wire is shorted to earth - as both wires are at 12v there's no potential difference between them so no current will flow

Is there any sign of damage to the wiring from where it emerges from the interior around the gear selector to the reverse switch connectors ? As mentioned above, it's quite possible the wires have touched the exhaust and melted the sleeving resulting in a short circuit upstream of the switch. You mentioned in an earlier post that you managed to blow the fuse whilst under the car so that might also suggest the problem is in that area

#12 dunkyb

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Posted 24 March 2020 - 05:26 PM

There's no sign of any damage to the wiring underneath the car, but I need to spend a day taking the seats out and carpet up, to get to the wiring and check it all properly.  

I'll report back once I've got this far...

 

Thanks for your help!



#13 GraemeC

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Posted 24 March 2020 - 07:01 PM

It won't short if those two wires are already 'joined' somewhere else and that is why they are both at 12V.
I suspect someone has connected them up incorrectly up behind the heater.



#14 dunkyb

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Posted 24 March 2020 - 07:23 PM

Hi GraemeC, does the heater unit have to come out to check?  This doesn't look like something I could attempt myself looking at the Haynes.

 

Apparently the newer models had a multiplug connector into the heater.

 

I think I understand why they pulled the bulbs out haha.



#15 dunkyb

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Posted 28 March 2020 - 09:04 PM

Hey guys,

As it was sunny today and we’re all in isolation, I decided to pull the seats out of the mini and the carpet back (as much as I could - Seems I have a one piece carpet!) Found The wiring coming up from the floor from the switch into a white connector block. Disconnected it and was reading 12V on both green/green+brown here. Also 0 resistance across both wires.

From here the two wires go into a sleeve, which disappears up behind the heater and I couldn’t trace it any further. Feeling with my hand, it felt very ‘flat’ so couldn’t quite understand what was happening to that wiring or where it went.

Anyone have any ideas? Guess it’s coolant out and heater out next to carry on tracing it?

Edit: Looked like someone had been there before as bits of the underlay were cut out in areas around the wiring! Maybe someone tried and failed in the past

Edited by dunkyb, 28 March 2020 - 09:05 PM.





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