Strange electrical fault

[amec Lurker Find all posts View Profile Close amec]

After some advice from an intuitive sparky.

Last weekend i ran some chunky cable from my dual battery isolator under the bonnet to the rear left quarter panel through the chassis rail and through the rubber grommet that the rear tank electricals and the rear left bumper lights run through. I cut a hole large enough in the grommet for the 8mm figure 8 cable to run through and wired it up to an Anderson plug.

All good there.

I got into the car to go to work monday morning and found that the reverse light on the dash was glowing faintly while in any gear, bright when in reverse. When i got home i found that all the rear left lights on the bumper and the rear quarter are all on. Both tail and brake lights, the left indicator , plus the reverse lights on left and right.

Also my main fuel tank gauge has stopped working, shows empty and it is full.

This arvo i pulled everything apart thinking i would find a wire arked out over everything else causing this problem. Not so. All the factory installed wiring is intact showing no signs of damage at all.

I put my multimeter across the lighting plugs and they all show 12v

Anyone got any clues as to where to look next?

[Ryzz Advanced Member Find all posts View Profile Close Ryzz]

Have you tired disconnecting the new cable from the battery and seeing if everything returns to normal.maybe the cable is tariff out somewhere causing this reaction.

[amec Lurker Find all posts View Profile Close amec]

Yep, did that this arvo. Had the new cable disconnected from the voltage sensitive regulator and all the lights shone bright and clear...

[Ryzz Advanced Member Find all posts View Profile Close Ryzz]

Yep, did that this arvo. Had the new cable disconnected from the voltage sensitive regulator and all the lights shone bright and clear...

Just so I got this right, even with the new cable disconnected the trail lights were still on?

[amec Lurker Find all posts View Profile Close amec]

Correct. Tail and other lights still on.

[Matty80 Avid PP Poster! Find all posts View Profile Close Matty80]

Did you damage on of the existing wires when you cut the hole in the original grommet? Sounds like a new earth fault.

[amec Lurker Find all posts View Profile Close amec]

I thought that too. So yesterday i stripped back the cabling insulation and could not find anything wrong.

[amec Lurker Find all posts View Profile Close amec]

I had another look at it this arvo with no change.

I did however notice that the fuel gauge will show the tank volume with the ignition on and the engine NOT running. With the engine running the gauge shows empty.

Any thoughts??

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Check for dislodged plugs where you've been working or possibly wrong plug
in socket etc

[amec Lurker Find all posts View Profile Close amec]

Yep, did that. There are 3 plugs in where the jack is stored. A blue one with a cover on it. A white one which looks like it has never been connected to anything and the rear quarter light plug which is screwed to the tail light.

[Dubbo Lurker Find all posts View Profile Close Dubbo]

I agree with Matty & Loz, sounds like an earth fault but have you disconnected the VSR from the battery? Then check where nad how the VSR is mounted, could a screw have gon through a wire? I know we are grasping at straws but hard to diagnose when it is not visible.

Cheers

[Matty80 Avid PP Poster! Find all posts View Profile Close Matty80]

I agree with Matty & Loz, sounds like an earth fault but have you disconnected the VSR from the battery? Then check where nad how the VSR is mounted, could a screw have gon through a wire? I know we are grasping at straws but hard to diagnose when it is not visible.

Cheers

Electrical faults are definitely difficult to work out remotely... Trial and error is the only way...

Remove all the wiring that was added for this project and verify the tail light and accessories fault once sorted then reinstall the mod. Does sound like an earth fault or a cross connection in the wiring.

Hard to say without seeing it.

[amec Lurker Find all posts View Profile Close amec]

Found it!!

The VSR was not at fault.

A workmate who is also a mechanic suggested i trace back to where the rear lights are earthed on the chassis. I pulled out the plastic trim from the inner left rear quarter. And right there i found a little mess of chafed wires. So i will get some small heat shrink, solder the wires back together. Wrap it all up and put it all in some conduit to protect it in the future.

Thank you all for your your suggestions.

Adam

[Matty80 Avid PP Poster! Find all posts View Profile Close Matty80]

Good find mate, glad to hear that you have it sorted!