Reversing lights staying on

[clyde]

Got home today after taking my car for a quick spin to dry it off after washing it and noted that the reversing lights were on, even with the ignition off and the key removed from the ignition. They were not on when I had finished washing but I do have to reverse it out of my drive so presumably this is when they came on.

I presume that "back up light" indicated in the fuse box lid as fuse number 14 is the one for the reversing lights but removing this does not extinguish the lights. I also tried removing fuse 15 as this is the back up light fuse for an auto but this didn't make any difference either. I don't know where the reversing light switch is so have not checked this. So I have two questions, firstly does anyone know if number 14 is the right fuse for a manual C4 and secondly where is the switch mounted?

I should also say that I did hose the engine down a bit to remove some oil but have done this numerous times without any side effects.

I have disconnected the battery in the meantime but any help would be greatly appreciated.

Clyde

 

[John Maddox]

I have had a look at the diagram of the gearbox housing and it looks as if the switch is on the left hand side (looking from the back of the car) towards the rear. Just a small module activated by a plunger when reverse selected. I can't find the fuse number.
Sounds like a short to earth - may have been caused by your engine cleaning I suppose - in which case a run to dry it out may cure.

 

[Mark Elder]

Clyde,
Just checked on my C4 manual (even black!) and definitely fuse 14, reverse lights go out if I pull it.

Also - fact that they stay on after ignition off suggests to me a short with another circuit somewhere rather than a problem with the switch on the gear box itself.

Hope it's easy to find...
Mark

 

[vitesse]

If it's the same as a 964,then the switch looks like a radiator thermostat switch-a metallic hexagonal plug with a 2 pin non-reversible electrical socket sticking out on the driver's side of the gearbox forward of the bellhousing-easy to get at with any undertray removed with the car on ramps.Mine wasn't working at all & fitted a new switch & then found that it was probably the connection contacts at the switch.[&o]

 

[clyde]

Thanks guys, found the switch on the gearbox and pulled the connector on Sunday evening. Not overly succesful as the lights still stayed on and I mangaged to break one of the connector pins from the wire [] . Ended up taking the central reflector out and removing the bulbs; at least that way I can still drive the car and not worry about the plastic distorting from the heat build up. There must be a short somewhere but can't see how flushing the engine would have caused it as it must have had a much bigger soaking during some of the monsoon rainfalls we've been having recently. Unless I just managed to spray a particularly sensitive area

On a quite probably related issue I do not have any heat reaching the cabin since taking the bulbs out.

I'll run it this week to hopefully dry anything off that ended up wetter than it should be and put the bulbs back in at the week-end and see how it is but I suspect a visit to an auto electrician will be required, at least to re-attach the connector.

 

[Mark Elder]

Clyde, I'd be a bit worried the short is pulling current even with the bulbs out (although I'm no electrician!) and might cause a fire[]. Is it worth pulling a few more fuses to see which circuit is shorting across to the reversing lights.

 

[silver7]

have you tried removing/cleaning the wiring harness plug that connects the bumper loom into the main loom? sits behind the plastic panel on the right hand side of the engine bay? Just an idea but would take a few minutes to try. Good luck

 

[D Ward]

ORIGINAL: clyde


Thanks guys, found the switch on the gearbox and pulled the connector on Sunday evening. Not overly succesful as the lights still stayed on and I mangaged to break one of the connector pins from the wire [] . Ended up taking the central reflector out and removing the bulbs; at least that way I can still drive the car and not worry about the plastic distorting from the heat build up. There must be a short somewhere but can't see how flushing the engine would have caused it as it must have had a much bigger soaking during some of the monsoon rainfalls we've been having recently. Unless I just managed to spray a particularly sensitive area

On a quite probably related issue I do not have any heat reaching the cabin since taking the bulbs out.

I'll run it this week to hopefully dry anything off that ended up wetter than it should be and put the bulbs back in at the week-end and see how it is but I suspect a visit to an auto electrician will be required, at least to re-attach the connector.

You wont have any heat in the cabin till you find out the cause of your reversing light issue, as the ccu thinks you are reversing the car, as when the car is in reverse the heater flaps on the engine close to prevent exhaust fumes from entering the cabin

 

[szklarek]

You wont have any heat in the cabin till you find out the cause of your reversing light issue, as the ccu thinks you are reversing the car, as when the car is in reverse the heater flaps on the engine close to prevent exhaust fumes from entering the cabin

So that's why the fan speed changes when I select reverse! Another 993 mystery answered!

Regards
Anton

 

[clyde]

ORIGINAL: D Ward

You wont have any heat in the cabin till you find out the cause of your reversing light issue, as the ccu thinks you are reversing the car, as when the car is in reverse the heater flaps on the engine close to prevent exhaust fumes from entering the cabin

The plot thickens. I didn't know that the flaps closed when reversing but makes perfect sense and the lack of heat is at least one thing less that I need to worry about I suppose.

I think that probably addresses Mark's concern about the wiring still shorting out as well because if the CCU isn't picking it up as live circuit it is presumably not drawing any current.

I did have a look behind the plastic panel for a connector or a fuse for the lighting loom but couldn't see either - it was pitch dark and I was working with the overhead garage lights and a small torch though. I'll have a proper look at the weekend although it was only the nearside of the engine that I was washing down so I would be surprised if it was that but you never know....

I wouldn't have this much fun with a modern car, would I? []

 

[clyde]

Woohoo, I now have working reversing lights and heater []

Still not entirely sure what the exact cause was but this afternoon I split and cleaned up all connectors that could possibly have been affected and put the bulbs back in and all is now well. I'm not sure how long the soldered connection I made on the pin connector for the reversing light switch will last because soldering when you're lying upside down under a car is not the easiest thing to do (as my burnt finger will testify) but we'll see.

Thanks for all the suggestions and advice

 

[John Maddox]

Well done.

 

[D Ward]

glad you got it sorted

think the moral of this story is dont wash your engine[]