99 GMC 3500 wiring issues

Check your messages. Going to send you a name of a guy that likes these diesels and has plenty of parts for them.

Yeah, and the white and brown wires were split and added to a new harness which went who knows where. Still can't find the external regulator, may have been taken out ages ago. Might price up both options. I can get another external regulator for cheap. But also don't need the big 190w alt.

I'm my case I opted for the bigger one. I'm doing audio in mine though and will need the extra power.

Okay, got some things sorted. I ended up buying an external regulator, and hooked it up temporarily via battery to alternator, which got the alternator working perfectly. This then allowed the tacho to get the correct signal and the great news is... the tacho works perfectly.

Next plan is to wire it in so I get the correct charge light, but for now at least I know it charges right. The volt gauge also sits happier. I can't take all the credit, my auto electrician friend provided most of the advice.

The slave CD player wiring arrived today, so will hopefully have all the stereo done tomorrow, which is kind of the last piece of electrical work.

So if anyone out there is having similar problems that I had, likely it not exactly the same given I didn't have a regulator, but you may find its the in-built regulator having problems.

I was given a couple good easy ways to test and happy to help if needed.

When I thought I was almost done...now having issues with tail light, indicators etc. Back to square one with that lol.

Its not the bulbs out either, its a matter of changing it to Aus standards and working out how to do it. If anyone on here has done this before, please let me know how you wired them up.

Hang on. That should already be done. Any idea who did the truck? Look on the compliance plate. There should be a name.

The oz compliance stuff I sort of know.

Yes it was already working once. But the wiring was all cut and no lights connected at the back. The headlights were a bit the same but everything was mixed up and ran off relays, which I have since deleted.

You might know though.. how should I wire up the headlights? as in.. I have the parkers as the small lights on the side (yellow covers), indicators as orange bulbs x 2 behind each clear double lower covers, low beam as the outside circular light and high beam as the inside circular lights.

They work okay that way, but not exactly ideal. The tail lights I have use 4 grounds each, all tech screwed to chassis from each light so it's pretty well grounded. Then using a test light found the wire corresponding to the signal I give, (reverse, low, brake and turn). This seemed okay but more than one wire controls one thing (US wiring, for which I have heaps of diagrams).

When I use hazards they almost all work perfectly, except the brake lights flashes also. When I indicate left its fast, even the interior light is affected. When I indicate right its flashing well but brake light left and right also coming on.

I think I'll ask my friend to come over and wire them all up, its probably easier. It seems about 3 different wires do the same thing - confusing me further.

Clinton said:

Yes it was already working once. But the wiring was all cut and no lights connected at the back. The headlights were a bit the same but everything was mixed up and ran off relays, which I have since deleted.

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Relays would be there to set up the wigwag flash you see on them.
Gutting all of that would leave you with the OE harness.
If you can give the fellow I gave you a call and get some export lights. It will make that fix a lot easier.

You might know though.. how should I wire up the headlights? as in.. I have the parkers as the small lights on the side (yellow covers), indicators as orange bulbs x 2 behind each clear double lower covers, low beam as the outside circular light and high beam as the inside circular lights.

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There are meant to be 6 Amber flashing lights on ADR specified vehicles and if one light fails it's supposed to flash quicker on that side.

As for parking lights they are meant to be clear only.

They work okay that way, but not exactly ideal. The tail lights I have use 4 grounds each, all tech screwed to chassis from each light so it's pretty well grounded. Then using a test light found the wire corresponding to the signal I give, (reverse, low, brake and turn). This seemed okay but more than one wire controls one thing (US wiring, for which I have heaps of diagrams).

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Diagrams are good, it will certainly sort out a lot of these niggles.

All of the wires should be single operation in that.

When I use hazards they almost all work perfectly, except the brake lights flashes also. When I indicate left its fast, even the interior light is affected. When I indicate right its flashing well but brake light left and right also coming on.

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Check you main body to cab grounds. That sounds like a bad ground to me.

I think I'll ask my friend to come over and wire them all up, its probably easier. It seems about 3 different wires do the same thing - confusing me further.

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May not be a bad idea to get a second set of eyes on it.

Yeh for the grounds issue. My friend said it has to be a ground issue...I think I saw a broken strap under the cab between the chassis rail and cab on the now passenger side under the seat. I'll reconnect that and see how it goes.

I'll also change out the parkers under the amber covers and use them as indicators. Then use parkers under the big clear covers which should get it ADR compliant. The tail lights are still a mystery, Ill connect the ground up first then retry them all.

Thanks for all the help too. I endeavour to get all this sorted. I can see the light lol