Jump to content

Help needed diagnosing electrical short in sidelights


megatoad

Recommended Posts

Help !

My 300 Tdi Disco has developed a fuse blowing short circuit on the N/S.

It has tail lights/indicators both in the bumper and rear light cluster.

At the weekend I did each of the following steps individually then put a new fuse in, then switched the side lights on :

  • Disconnected all sidelight bulbs – fuse blew.
  • Disconnected the rear bumper wiring loom from main loom – fuse blew.
  • Removed all the towing electrics from the loom in O/S which had been scotch blocked on rather than plugged in – Fuse still blew.
  • Checked as many points where harness when through metalwork as I could find – blew another fuse !
  • Removed and disconnected rear light unit from vehicle – still popped a fuse!

The motor is a very tidy 3 door M reg with very little welding done to it (my brother has owned and run it for the last 5 years before passing it onto my wife in October).

Also while investigating around the front wiring harness I found this strange connector on the N/S headlight loom, can anyone tell me what it is for ? (possibly the LR / Diagnostics plug)

I sprayed it with WD40 just in case but, pop, blew another fuse.

b3ek.jpg

Link to comment
Share on other sites

Think that's for the little motor for the headlight leveling if fitted! Just ignore it for now - there will be the same on the other side.

Back to your problem - must be a dead short somewhere if it's popping the fuse so quickly - have you done the same exersize for the front of the vehicle - quite possible water ingress behind the dash, the relays are mostly in the kick panels, or above the passenger footwell (sorry don't recall which one you'd be looking for - rave manual will tell you) or maybe the switch?

The loom for the back runs accross the dash to the passenger side a post and up along the roof / gutter line under the head cloth. It's held in place with duct tape and metal tabs - can often rub through - think there may be a multiplug to disconnect and isolate that section of the loom in the passenger footwell about level with the bottom of the dash. I think the head lamp looms exit both sides of the bulkhead just above the inner guard.

Get your hands on the electrical troubleshooting manual - invauable for this sor of thing as it shows where all the relays, multiplugs, earths are for each circuit.

Steve

Link to comment
Share on other sites

Thanks Stevie

Someone else mentioned the healight leveller, this is a nice low spec 3 door motor without too many electricals and no sun roofs (I used to have have an ES with everything).

Yes the short is immediate, I switch on the sidelights, there sounds like a relay click, then I can see the flash as the fuse blows. Looks like I have to do some dash dismantling.

Thats next weekends job, along with connecting up the heated mirrors on the 110 :), fortunatly theis is the 4th car, so she is back in the peugeot

Gottat dismatle the centre console in that to replace the CC backlights, apparently a 2 hour job, and that comes from the horses mouth, her vrother is service manager at the Peugeot dealer !!

Link to comment
Share on other sites

Could it be the dimming relay itself? I mean the one that causes the headlight bulbs to shine really dim when in side-light mode? I removed mine as it just kept clicking and flickering from dim to bright. Remove yours and see what happens?

Link to comment
Share on other sites

Might not be fited - rave shows it on the 95 300tdi disco, fed from the multi function unti via a (UW) blue with white wire off pin 5 of the main lighting switch, and a feed off fuse no 8 off the right hand side lamp circuit - if it's fitted there should be 2 relays on the passenger footwell, and the resistor on the lhs of the bulkhead engine side, differs slightly on the later models...

If you need it I may be able to post diagram later when I get home?

Steve

Link to comment
Share on other sites

Mine had both... little 5W5 'sidelights' but the main dim/dip lights also shone (dimly). Once I removed the relay, I just got sidelights.

Just another thought, if the fuse is blowing when switching to sidelights, you're also turning on the internal dash lights, the gearbox lighting (if auto), the rear number plate light, and of course the sidelights. Could be any of these causing the issue I suppose?

Link to comment
Share on other sites

Might not be fited - rave shows it on the 95 300tdi disco, fed from the multi function unti via a (UW) blue with white wire off pin 5 of the main lighting switch, and a feed off fuse no 8 off the right hand side lamp circuit - if it's fitted there should be 2 relays on the passenger footwell, and the resistor on the lhs of the bulkhead engine side, differs slightly on the later models...

If you need it I may be able to post diagram later when I get home?

Steve

That would be very helpful Steve

All info is welcome.

Any idea where I could find the electrical trouble shooting manual too?

Link to comment
Share on other sites

Check the number-plate light and wiring - though I would have expected that to be powered from the offside sidelight loom.

Also, I'm not sure about Discos [i'm a Defender man myself] but I recall one car of my acquaintance had a red light in the trailing edge of the doors which was powered by the sidelights and the wiring to this was known to chafe where the harness goes through into the A-post causing fuse blowing and spurious central locking behaviour.

While trying to trace these faults, making up a "fuse-fudger" harness is useful - two small male blade-connectors that push into the slots where the fuse goes, a few feet of 2-core cable, and a headlight bulb [one with one filament failed is OK].

Hook up the fuse-fudger in place of the fuse and switch on. Hang the [now lit] bulb somewhere you can see it, then go through the wiring wiggling/disconnecting things while looking at the bulb.

The bulb will limit the current to a safe level [5 amps for a 60Watt heaflamp bulb] while you're trying to find the fault.

Link to comment
Share on other sites

Thanks Stevie I have managed to download the guide, I will have a look through that tonight.

Thants too Tanuki that light bulb trick sounds like a good idea. (I am a Defender man too, 110 daily and then we both RTV the S1, the Disco is the wifes spare car :blink: )

Link to comment
Share on other sites

You can't beat the simplicity of the Defender wiring - I'm amazed at how much copper is in a Disco lol...

according to the diagram the number plate lamp is on the lhs / near side circuit!

Don't think the lower spec vehicles had the courtesy / red lamp in the trailing edge of the doors? It was a range rover thing afaik although the holes are all there for them, even the rear tailgate....

Enjoy the read....

Link to comment
Share on other sites

  • 3 weeks later...

Arghhh, OK pulled rear door trim off and inspected all the wiring, nothing suspicious.

Then though, hmm rear interior light needs changing so I removed that from the pilar on o/s and removed the dud bulb. popped a fuse in for a test and bu##er me if all the lights worked !!

Who would have thought some brummie muppet would have wired the rear door interior light to the n/s loom !!

So the missus can use her Disco again and park her 307 up.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy