One Headlight isn't working - Driver Side Fuse Keeps blowing

[kevboost7]

I checked, i dont think it was the indicator stalk. The problem just magically fixed itself though. 

[niZmO_Man]

On 29/04/2025 at 1:59 PM, kevboost7 said:

The problem just magically fixed itself though.

From experience, it will come back to bite you haha.

[dbm7]

12 hours ago, niZmO_Man said:

From experience, it will come back to bite you haha.

...yep, in the dark of a wet rainy night most likely 😃 

[GTSBoy]

7 minutes ago, dbm7 said:

...yep, in the dark of a wet rainy night most likely 😃 

That would be the better outcome. The one where the car is burning to the ground while also being broken down in the dark of a wet rainy night is also possible.

[MBS206]

4 hours ago, GTSBoy said:

That would be the better outcome. The one where the car is burning to the ground while also being broken down in the dark of a wet rainy night is also possible.

Hopefully not, since he knows the fuses work ha ha ha

[GTSBoy]

3 minutes ago, MBS206 said:

Hopefully not, since he knows the fuses work ha ha ha

Yeah, but knowledge of one wire's insulation worn through to short on earth implies the possibility of other wires doing the same.

I had my power steering die, because the wire that runs to the solenoid valve on the rack runs in the same loom as the power wire for the O2 sensor. And when the O2 sensor/wire did something stupid and burnt part of that loom to death, the only indication was the shit(ter) fuel economy and the heavy steering. It took deep excavation of the looms in the bay to find the problem. Not wear through in that case, but similar shit.

[dbm7]

He's right ~ there is no 'magic' with stuff like this ... it is more likely that in the process of looking for the short, the loom/wire 'incidentally' got moved in the process, thus removing the short ~ now, that maybe a wire (in a loom) rubbing against the edge of some grounded metal, that's worn through the insulation, causing the (now intermittent) short to ground. If one wire in a loom has been damaged in this fashion, it's reasonable to presume that other wires beside it may have also be damaged, and now exposed...you can bet the green crusty copper corrosion will start...

...that'd be a pisser, Murphy's Law steps right in as GTS observes...but worse, something like that is easier to find when shorted...ie; unplug bulb and fuse, and put multimeter in continuity mode so you get constant beep, and carefully poke about hoping to find if some movemet of the harness stop the beeping....

...it's still all a bit Arnie tho' ..It'll be back... 😃

[kevboost7]

After all the troubleshooting, the only thing i can think of that would cause it is the headlamp relay. Could that have gone bad and caused the short? 

[dbm7]

6 hours ago, kevboost7 said:

After all the troubleshooting, the only thing i can think of that would cause it is the headlamp relay. Could that have gone bad and caused the short? 

Very unlikely...

[kevboost7]

Took the car out for a drive.

Good news - both headlights are still on.

Bad news - my fuel gauge is pinned in the full position. 

 

[GTSBoy]

41 minutes ago, kevboost7 said:

Bad news - my fuel gauge is pinned in the full position.

That doesn't sound like bad news. That sounds like the never ending packet of TimTams.

[kevboost7]

7 minutes ago, GTSBoy said:

That doesn't sound like bad news. That sounds like the never ending packet of TimTams.

yes wtf, its never ending i swear. im literally losing hair

[MBS206]

From memory when the tank is full is when the resistance from the fuel sender reads its absolute lowest. It sounds like the short has made its way to the fuel sender wires...
Which also means the short could possibly be in / around the cluster.

[dbm7]

Correct ~ fuel gauge receives power (usually about 10volts) from a linear regulator on the cluster board (gives a stable reference voltage), and as you say, via a variable resistor to ground (float level) ; high resistance when tank empty, a low resistance when tank full. As you surmise, if the fuel sender wire was shorted to ground, there'll be full defection of the fuel gauge needle. I haven't got an R34 wiring diagram, but going by the R33 spaghetti schematic, about the only thing common here between headlight & fuel gauge circuits is the SMJ connector...

[kevboost7]

What is the SMJ connector?

[dbm7]

9 hours ago, kevboost7 said:

What is the SMJ connector?

Ahh...should have been clearer ~ there's 2 ... SMJ = super multi junction (connector)...

 

...this is connector 6 & 25 in above image -- body harness to engine loom (6) & body harness to main loom (25)

Headlights go to front via connector 6 ; fuel gauge goes to tank sender via connector 25  ...like I say this is R33 diagrams, but at a pinch R34 won't be too far different. *IF* the two ground faults are related, this can be the only place where both wires converge (as one runs to the back, the other to the front)...

....thing is, you probably need to establish if the faults are related (unless you examine that area and find obvious chaffing on the looms there to body ground)....*IF* the fuel gauge is still broken (full needle deflection), I'd be headed for the boot, remove fuel sender wire, key on and measure the voltage there ~ it should be roughly 10volts. If that's ok, check sender to ground resistance...if this is a dead short to ground (and there's fuel in it), then sender has failed or something funky has happened to wiring in the tank.

edit: ahh...rereading the thread, this is R32....above fuel sender test still valid tho'

Edited May 6 by dbm7

[GTSBoy]

And the full R32 GTR wiring diagrams are also freely available.

Hmm.... there's supposed to be an auto replace that would have linked the thread. Here it is, manually

 

[MBS206]

Those two circuits would end up in the same looms from near cluster/stalk all the way to the SMJ from memory, so fault could be anywhere between cluster/stalk area down to the SMJ, and even in the SMJ.

 

Other possible f**kery is some cars for compliance in Australia had extra resistors added to dash / headlight wiring to alter dash bright ness, so could be some dodgy free electrons floating out of that area if it's done in this car.

[kevboost7]

On 06/05/2025 at 7:49 PM, GTSBoy said:

And the full R32 GTR wiring diagrams are also freely available.

Hmm.... there's supposed to be an auto replace that would have linked the thread. Here it is, manually

 

Wow, i wish i found this sooner.