Fuse keeps blowing

[DWCamo]

Hi all,
My 12A fuse for the windscreen wipers, stop (brake) lights and gauges keeps blowing. Any suggestions on what I should check first?

Cheers, DW

[TK_Co]

I always found aluminium foil in the trailer plug was a good trick :)

2nd, I would suggest you have a short harness/loom. Try lengthening them :)

[DWCamo]

TK_Co,
thanks for replying. I'm not sure if I follow your drift with the aluminium foil in the trailer plug trick?

I've had a preliminary check to try to find any obvious shorts but will have another.

I'm thinking the recent wet weather in my part of Oz may have something to do with it. Thankfully the suns out now. Drying out.

Cheers, DW

[Chris078]

Hi all,
My 12A fuse for the windscreen wipers, stop (brake) lights and gauges keeps blowing. Any suggestions on what I should check first?

Cheers, DW


try the connections at the back of the gauges, moisture can get in there (well, it did in mine).
be careful, some of the wires are quite short when you pull the facia off, and getting the speedo cable off the back of the speedometer is a pain, but once you do, you'll be able to poke around back there.
try and either mark or make a note of where the cables from the back of the gauges go, if one comes off and it's unmarked, as I found out, it can be somewhat difficult finding where it goes amongst the spaghetti that is back there!

I think the other suggestion was make sure that the trialer plug is dry. water may be in there shorting it out.
also check where the main cables come out of the chassis next to the rear right brake light. mine were worn through from rubbing on the hole and were shorting out there as well :mad:.

[TK_Co]

TK_Co,
thanks for replying. I'm not sure if I follow your drift with the aluminium foil in the trailer plug trick?

Cheers, DW

If you want to play a prank on someone, get aluminium foil, scrunch it up, lift the little flap on the trailer plug and insert foil. When ever the light, indicators or brakes are used its blows the fuse. Takes some people for ever to find !! ..... Well so I've heard from a mate of a mate. 😀

[Chris078]

If you want to play a prank on someone, get aluminium foil, scrunch it up, lift the little flap on the trailer plug and insert foil. When ever the light, indicators or brakes are used its blows the fuse. Takes some people for ever to find !! ..... Well so I've heard from a mate of a mate. 😀

That is EVIL! :rocket:

[rar110]

I had the same problem.

The windscreen wiper power supply wire had rubbed against the steering column vertical support behind the instrument panel.

I insulated both the wire and column support.

[Phil B]

Also check the loom where it goes through the firewall behind the air filter
Often wears through the insulation there causing a short
Phil

[BadCo.]

Lastly, take your rear brake/indicator/reverse light cover off and make sure the brake light globe holder is seated correctly.

I had this same problem, the base of the globe would short against the earthed metal frame. Took me sooooo long to find the fault.

[DWCamo]

I have narrowed it down to the stop (brake) light circuit and reckon it could be the stop light switch because, until the fuse blows, the stop lights are stuck on (i.e. Illuminating all the time). My question is, how do I access the stop light switch? Should I take the underside of the dashboard off? Any guidance would be very much appreciated.

[BadCo.]

...the stop lights are stuck on (i.e. Illuminating all the time)...

Are the globes the correct type with the offset pins?

[Phil B]

The stop light switch is mounted on the back of the brake master cylinder tower between the tower and the fire wall.
The easiest way to see it is to take the cover plate off the mc tower so that you can see inside and you will then see how it works. I would still check for shorts (and bulbs as BadCo suggested) as the switch is reliable IMO.
Regards,

[DWCamo]

Thanks fellas,
BadCo. - Yes the globes are the correct type.
Phil B - I'll advise my mechanic mate who is checking it out for me.

[DWCamo]

Further investigation today revealed that my stop light switch had broken free from its mounting position on the tower due to the end piece of plastic thread breaking off (approx 2mm). Thankfully there is still enough thread on the switch to work with so I'm planning to reassemble tomorrow. Btw, removing the broken piece of switch in the tower was a PITA due to it probably having been glued in with loctite. Fingers crossed I'll be operational again tomorrow.
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[Chris078]

It's always something tiny and almost unfindable! well done tracking that down.


By the looks of that drip on your floormat in that photo, you need a new clutch master cylinder as well.

how easy was it to take the brake booster off?
I need to get in there to clean out some rust, but have been putting it off.

[DWCamo]

It's always something tiny and almost unfindable! well done tracking that down.


By the looks of that drip on your floormat in that photo, you need a new clutch master cylinder as well.

how easy was it to take the brake booster off?
I need to get in there to clean out some rust, but have been putting it off.


I'm very lucky to have a mate who's a very experienced mechanic. We worked on it for quite a few hours over the weekend and I think my fuse issue is now sorted.
In a nutshell, after refitting the stop light switch and reassembling the tower we replaced the stop light globes, which at first glance appeared to be OK but were probably totally cactus inside due to being on too long (too much heat) because of the switch failure described earlier.
The drips on the floor mat are from the WD40 we sprayed on the tower bolts (x6) before undoing them. It's quite easy to remove the tower and brake booster (as one unit) after disconnecting the master cylinder from the booster (only 2 bolts).

[DWCamo]

OK, here is the final chapter in this story (finger crossed).
The fuse blew again today (grrrr) when applying the brakes so I undid the connections to the stop light switch, replaced the fuse and applied the brake pedal again. Sure enough, no more blown fuses, so I then unscrewed the stop light switch from the tower to inspect it (see photos attached). Then I had a Eureka moment. I found the short. The plastic coating on the wire was split when bent at the angle it would be subjected to in its normal position, which would allow the bare wire to contact the fire wall and short. I insulated said wire with liberal amounts of electrical tape and reconnected the stop light switch. No more blown fuses. So far so good......945469454794548