Blowing fuse, can't work out why.

I have a problem with the Tail Light fuse blowing.
I have looked up on the wiring diagram and this fuse does the Park lights, tail lights, number plate light, dash and switch Illumination and headlight warning chime.
I have disconnected every external light and the trailer plug and it still blows the fuse, have also been checking every bit of wiring i can find for damage but cannot find any.
I have been trying to fix this for 3 weeks now and it is driving me mad and can't use the car at night while it is like it.

Anybody have any ideas how to find a short like this as it is driving me nuts and I am too stingy to pay an auto electrician.

Quote:

---

Originally Posted by TPC

I have a problem with the Tail Light fuse blowing.
I have looked up on the wiring diagram and this fuse does the Park lights, tail lights, number plate light, dash and switch Illumination and headlight warning chime.
I have disconnected every external light and the trailer plug and it still blows the fuse, have also been checking every bit of wiring i can find for damage but cannot find any.
I have been trying to fix this for 3 weeks now and it is driving me mad and can't use the car at night while it is like it.

Anybody have any ideas how to find a short like this as it is driving me nuts and I am too stingy to pay an auto electrician.

---

Had the same problem, I believe the issue was found in the left hand rear loom somewhere........ I gave up looking and took it to an auto sparky. Fixed it for $100.

Hopefully someone can help with troubleshooting, had the exact issue and it was trailer plug wiring underneath rubbing on chassis.

Have you done anything aftermarket connecting to these that you forgot about to check too?

My first thought was the trailer plug so disconnected that and have disconnected everything aftermarket.
It may end up being an auto elec job. :(

have you done the christmas tree light conversion?

take both light clusters out and check the rear passenger side loom, you make have a wire rubbed through where it enters the body there,

Just a chance look in the jack compartment mayhave accidently put the jack on the loom
or it maybe rubbing on the jack

Problems like this can be a real PIA as you have discovered.

One method is to replace the fuse with a test globe.
That way you are chasing voltage instead of blowing fuses.
While ever the globe is lit the short is present, whatever you disconnect that turns off the globe is the fault.

All you can do is split the system into sections.
If you unplug the connector M96/B102 near the RF guard that will disconnect the rear lights so if the fault is still present it will be in the switching or the front loom/lights

If the fault is in the front you next need to rule out the dash lights, dimmer etc.

Have you checked where the cable for the trailer plug is spliced into the vehicle loom?
Have you had anything in the dash apart recently, fitted a new radio or accessory?

Quote:

---

Originally Posted by Clunk

have you done the christmas tree light conversion?

take both light clusters out and check the rear passenger side loom, you make have a wire rubbed through where it enters the body there,

---

I did take out the rear light assemblies a few weeks back to check what was involved in changing over to the fully functional ones, will check behind them as i could have pinched a wire.

Quote:

---

Originally Posted by roofy

Just a chance look in the jack compartment mayhave accidently put the jack on the loom
or it maybe rubbing on the jack

---

Another possibility, will check there too.

Quote:

---

Originally Posted by the evil twin

Problems like this can be a real PIA as you have discovered.

One method is to replace the fuse with a test globe.
That way you are chasing voltage instead of blowing fuses.
While ever the globe is lit the short is present, whatever you disconnect that turns off the globe is the fault.

All you can do is split the system into sections.
If you unplug the connector M96/B102 near the RF guard that will disconnect the rear lights so if the fault is still present it will be in the switching or the front loom/lights

If the fault is in the front you next need to rule out the dash lights, dimmer etc.

Have you checked where the cable for the trailer plug is spliced into the vehicle loom?
Have you had anything in the dash apart recently, fitted a new radio or accessory?

---

Have not heard of using a globe to test but it makes sense so will try.
Will also try disconnecting the rear lights to isolate part of the car.
The trailer plug was the first thing i checked, they were easy to isolate as they plug in line with the cars original plug/sockets so could just unplug it.
I have not had the dash apart for over two years when i changed over the stereo but that still could be where the problem is as it is a larger unit and may have slowly rubbed through a wire.

Thanks all for the suggestions, more things to try now, if i knew it would only cost $100 i would just get a auto elec to fix it but had a mate take his cruiser to one for a similar problem and cost him over a thousand.

Think back a few weeks... did the fuse start to blow before or after you had the lights apart?
It might be a good place to check again.

Probably as much as 90% of electrical faults are caused by us humans touching things that weren't broke

The idea of the globe is to limit current.
If you use a small wattage globe like an interior light, a test light like in the screwdriver style probe or an LED in place of the fuse it means that only milliamps flow in the circuit so nothing gets fried or melts.
Very handy trick when you get bad power shorts to earth, switch mode power supply faults etc
You can power the circuit up and actually chase voltages to find the short rather than just picking things out of your butt to disconnect and blowing a gazillion fuses

You didn't install a stereo or anything did you.

Quote:

---

Originally Posted by the evil twin

Think back a few weeks... did the fuse start to blow before or after you had the lights apart?
It might be a good place to check again.

Probably as much as 90% of electrical faults are caused by us humans touching things that weren't broke

The idea of the globe is to limit current.
If you use a small wattage globe like an interior light, a test light like in the screwdriver style probe or an LED in place of the fuse it means that only milliamps flow in the circuit so nothing gets fried or melts.
Very handy trick when you get bad power shorts to earth, switch mode power supply faults etc
You can power the circuit up and actually chase voltages to find the short rather than just picking things out of your butt to disconnect and blowing a gazillion fuses

---

The problem started after doing some sand driving through dunes and on beaches, plenty of corrugation and some heavy bumps which would be just the thing to make some badly positioned wiring rub through.
Don't know why I didn't think to use a light in place of the fuse as it makes sense and I am a Technician myself.:icon_bonk:

the loom runs along the top of the chassis in the rear wheel arch maybe you cut the loom there
during one of those heavy "bumps", You should be able to see any damage.
Id also check where to OE loom splices into the towbar loom, that is a common area for faults

I have just about given up on finding this short and will have to take it to an auto elec to get sorted.
I have eliminated all the front and rear lights and disconnected most of the internal switches that have illumination.
Replaced the fuse with a 1w globe for the tests and it only has .035v on the output side and I can measure this same voltage at the lights and switches.

Bloody frustrating as I don't like being beaten.

I found the short Yaaaaaaa.:Yahoo!:

It was something I had done, I had taken out the ashtray in the front center console and replaced it with USB sockets and had screwed through the wiring for the ashtray light that I did not know was there, sort of thing I would kick an apprentice up the backside for. :1087:

Very happy its fixed now, time to put the car back together.

Gutsy admission mate. Glad you solved it.

Win...

Been there, done that, hid the evidence, noone knows any different.

Happy to provide the size 13 boots for the kicking at our next meet up:). Glad you found it without having to pay someone.

consider yourself kicked lol
Good thing,,,,, you can rest easy now and not worry about,,,,, every minute of the day
Good tip on the light by ET,

It's always something you've done yourself ;)

Quote:

---

Originally Posted by AB

It's always something you've done yourself ;)

---

speaking from experience I see there AB.....

Quote:

---

Originally Posted by wa 489

speaking from experience I see there AB.....

---

He is a wise man... Being that he has been there and done that haha

The real annoying thing is that simple mistake cost me about 3 days of puling things apart and cursing.
Also blew about a dozen fuses before I saw ET's idea of replacing the fuse with a globe for testing.

Nice work mate glad you found it

Show us your USB sockets I want to see where and how you mounted them as it sounds interesting

All your earth's good ?

Well done champ, you reached 25 posts.

Quote:

---

Originally Posted by TPC

The real annoying thing is that simple mistake cost me about 3 days of puling things apart and cursing.
Also blew about a dozen fuses before I saw ET's idea of replacing the fuse with a globe for testing.

---

thats a keeper , a great idea

I had the same issue but caused by something different. I will post here for future reference just in case. Hopefully it can save someone days of stuffing around.

Vehicle: '96 GQ Patrol DX 4.2TD

Problem: every time the headlights were switched on, the "tail light" fuse would blow. This supplied illumination to the tail lights, dashboard, center console, and possibly other components like number plate light etc.

The cause: Wiring harness for the stereo head unit. (CD Player)

As I discovered, the wiring harness for the head unit did not have an earth wire, but instead there was a PINK wire with a Blue stripe that was powered when the lights were switched on. Due to no earth wire I naturally assumed this was earth as it was the only wire left after the rest were connected, it was also tested as dead before I connected it (obviously because I didn't have the headlights on at the time). This caused an earth leakage through the pink wire and into the CD player, then out through the casing and into the chassis.

It was an easy fix, but hard to pinpoint. All I did was isolate the Pink wire coming from the loom, and then connected my CD Player earth wire to the chassis.

I was seriously going WFT, what is that wire even for??? Then it dawned on me.... the old original cassette deck units that were in there did not have illuminated display and buttons, they relied on an external power source... so when it's night time and you switch on your lights, the dashboard, centre console and the cassette tape deck all light up!

Quote:

---

Originally Posted by DaveGQ

I had the same issue but caused by something different. I will post here for future reference just in case. Hopefully it can save someone days of stuffing around.

Vehicle: '96 GQ Patrol DX 4.2TD

Problem: every time the headlights were switched on, the "tail light" fuse would blow. This supplied illumination to the tail lights, dashboard, center console, and possibly other components like number plate light etc.

The cause: Wiring harness for the stereo head unit. (CD Player)

As I discovered, the wiring harness for the head unit did not have an earth wire, but instead there was a PINK wire with a Blue stripe that was powered when the lights were switched on. Due to no earth wire I naturally assumed this was earth as it was the only wire left after the rest were connected, it was also tested as dead before I connected it (obviously because I didn't have the headlights on at the time). This caused an earth leakage through the pink wire and into the CD player, then out through the casing and into the chassis.

It was an easy fix, but hard to pinpoint. All I did was isolate the Pink wire coming from the loom, and then connected my CD Player earth wire to the chassis.

I was seriously going WFT, what is that wire even for??? Then it dawned on me.... the old original cassette deck units that were in there did not have illuminated display and buttons, they relied on an external power source... so when it's night time and you switch on your lights, the dashboard, centre console and the cassette tape deck all light up!

---

A lot of new CD players will utilise that wire too, they dim the display when your lights are on.