Voltage drop when brakes applied

Well now the mystery deepens.
Just took the steering column cover off. lots of mud/dust but no signs of any melting/shorting.

Unplugged the light switch just to be sure and the parker lights are still half lit (the headlight light on the dash is half-lit as well)
very strange.
not sure what to do from here.

If it makes any difference, at the moment the entire rear harness is disconnected. Is there something that makes the driving lights go on if there is a missing connection in the rear?
Only thing I can think of now. Guess I'll find out in a couple of days when I wire it back up, unless one of you genius' can think of something in the meantime :confused::confused:

the headlight switch could definitely be knackered- i think thats a fairly common problem- but i cant see how the parkers would stay on when the earth is disconnected from the battery. i would'nt have thought that was even possible; you've clearly got some gremlins in there!

my truck also had some wiring connections at the back that had not fared well after being completely caked in mud for who knows how long. i didnt realise there was a problem until the tail light on my trailer stopped working. some were ok after a good cleaning but some needed replacing. the wiring there is surprisingly vulnerable. those metal sheets- whatever they're called- between the mud flaps and the tail lights are brilliant for smuggling a few kilos of concealed mud!

ok we were both typing at the same time there. if the switch looks ok i would suggest you start tracing the wires back from the parkers until you find where they are getting power from.

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Originally Posted by The Beast

the headlight switch could definitely be knackered- i think thats a fairly common problem- but i cant see how the parkers would stay on when the earth is disconnected from the battery. i would'nt have thought that was even possible; you've clearly got some gremlins in there!

my truck also had some wiring connections at the back that had not fared well after being completely caked in mud for who knows how long. i didnt realise there was a problem until the tail light on my trailer stopped working. some were ok after a good cleaning but some needed replacing. the wiring there is surprisingly vulnerable. those metal sheets- whatever they're called- between the mud flaps and the tail lights are brilliant for smuggling a few kilos of concealed mud!

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oh yes. Mud flap strengtheners they are called. Mine are currently off. They were clogged with mud up to the floor (including the wiring harness that was tied up above them :censored:. Nicely rusted they are. stripping them back and re-painting.

If yours were full of mud, I'd seriously recommend pulling out the taillight fitting and checking the interior of that rear crossmember. Mine was completely full of mud as well.

good call. another job for the weekend.

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Originally Posted by The Beast

good call. another job for the weekend.

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check the wiring harness while you're under there. Mine was worn through where it comes out of the chassis and also where it enters and exits the rear crossmember.

If you have the time. It's reasonably easy to disconnect all the tail lights, and pull the harness out of the rear cross member to fully check it.

Just remember to label everything(especially the wires!) before you pull it apart.

I disconnected the convoy lights and removed the wiring for them while I was back there. Removes quite a few extra wires.

This job keeps growing. I've now removed the jerry can holders in order to clean off the rear cross member properly.
The bolts holding them on are shot. Would have hated to see what would have happened driving over some rough stuff with full cans in them; they are all rusted half to 3/4 through.

So I need new bolts. would the High-Tensile bolts you get from Supercheap etc be good enough or should I get something else?

These are what I was thinking of. Also does anyone know the difference between the yellow and blue packs? The yellow ones seem to have yellow coloured bolts, whereas the blue look like stainless. I can't find any information about what the specific difference might be.

Yellow is metric, blue is imperial.
They are all high tensile and will be OK for what you need.
Regards,

If you disconnected the earth at the battery and the lights were still on and if you don't have a second battery fitted some where then you probably have a very dirty battery or a damaged battery housing. Pull battery out, clean it and check housing for cracks.

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Originally Posted by camel58

If you disconnected the earth at the battery and the lights were still on and if you don't have a second battery fitted some where then you probably have a very dirty battery or a damaged battery housing. Pull battery out, clean it and check housing for cracks.

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brand new battery, and battery bay is prestine.

May have found the issue.
behind the instruments the ground cable for the switch had come loose and was dangling.
I think it was touching on something just enough to create a partial ground.
about to start it up to confirm.

<edit> seems I may be in the right area. I think i may have connected the loose ground wire to the wrong spot - now the parker lights come on when I hit the brakes :/