One hell of a strange problem

[Cypher]

I've got one hell of a strange problem, it's a bit long winded but it will definatly leave you scratching your head:

1989 WT Sierra Hardtop, I decide its time for a headlight upgrade, so in goes Narva Headlight Conversion kit plus Ultima 175s, with brand spaking new wiring loom and relays, the lot. All goes in sweet, and on the drive out to Bribie to check her out as I'm crusing out of Ningi suddenly something goes pop (main fuse) and I'm forced to roll to the side of the road with limited electrics. Ok, so main fuse gets replaced and I drive home to investigate.

Heres where it gets wierd.

The main fuse will only blow if the headlights are on + high beams + spotties + engine running it seems. Only seems to blow when you get up it/give the engine a hard time/high revs. None of the cabin fuses have blown/are blowing. When the fuse goes the dash lights go really bright for a split second as the fuse blows then the warning lights are on as the engine runs off the alternator. Sometimes as the fuse blows the windscreen wipers come on and do one cycle. As the fuse blows I've noticed what feels like the ignition being cut but only for the split second as the fuse blows

No obvious signs of melted wiring, nothing smells burnt. Checked and rechecked and tripple checked new headlight loom...and I re-wired it entirely...and I've also disconnected it entirely from the car and it still blows the main fuse. Ran with the tacho removed, still blows. Put a brand new alternator in, still blows. Checked all earths...still blows.

So I think I've narrowed it down to a few things. I know that the problem lies somewhere between the battery and the cabin fuse box as none of the cabin fuses are blowing...so I'm currently in the process of splitting up the wiring loom and removing the main battery wire from the entire thing.

In doing so, and poking around under the dash, I've spotted the emissions control box, which got me thinking it might be related to that (engine load + revs + whatever = emissions control box trying to switch something = short = blown fuse). I pulled that out and had a look inside, nothing burnt or melted.

Anyway, I'm done stuffing around with it for tonight, i'll be back at it tomorrow after work though...


...Any input would be muchly appreciated.

[BlueSuzy]

lol that is so funny i just almost pissed my self. never heard that b4 ha ha ha

[built4thrashing]

where did you get the power from to run the new headlights? hopefully its from the barrery not from the original headlight power wire. everything ive added to mune is wired off the battery with a relay as factory loom wont be big enough to run high current accessories.

[Cypher]

where did you get the power from to run the new headlights? hopefully its from the barrery not from the original headlight power wire. everything ive added to mune is wired off the battery with a relay as factory loom wont be big enough to run high current accessories.

Yep, new headlights running from the battery via relay.

[Mudgee_Engineering]

Hey how are you?
First i would disconnect your upgrade and wire all back to stock. Retest the system. It may be coincidence that it happened when fitting the upgrade, but nothing to do with it. Process of elimination.

If you go back to stock and it still does it, then you know its not directly to blame. But this doesnt mean that the upgrade didnt highlight the problem.

Goodluck and i will be watching out to see how you go.

Cheers

[Cypher]

Hey how are you?
First i would disconnect your upgrade and wire all back to stock. Retest the system. It may be coincidence that it happened when fitting the upgrade, but nothing to do with it. Process of elimination.

If you go back to stock and it still does it, then you know its not directly to blame. But this doesnt mean that the upgrade didnt highlight the problem.

Goodluck and i will be watching out to see how you go.

Cheers

Thanks for your input.

I have disconnected the new loom/relays entirely, and returned it to stock bar having the headlights plugged in and the fuse still blew.

Last night I split up the loom and seperated the main positive wire from the engine loom up to the plug in behind the dash. Tonight I'll start on the interior loom, though I'm trying to decide if I want to take the dash out or not ...

[gman79au]

it sounds like the link between the battery and alternator is faulty what i mean is the 12volts which should tell the regulator the condition of battery voltage. the alternator should have a large wire going to it fastened by a nut to its terminal and also a plug with maybe 2 or 3 wires. my guess is get a manual first of all second find out of the small wires which is suppost be positive and than make sure you know what the other wires do too (one should be for your battery light and one earth) run a wire from the positive to positve teminal of battery and see if it fixes it.
If the battery is disconnecting from the circuit it will also do make globes and fuses blow. or if it has a broken cell it might try a different battery if you have a spare too.

[gumtree]

yep, to me it also sounds like a faulty alternator setup. try this. if u have racq call them out coz they have a current meter thing they put to your car to c how much charge the alternator is giving. or u can go buy one and do it yourself but racq is free if u have them. it should stop the current at 13.8v or something and it sounds like its not limited and gives alot more.

[zooki]

do you have an uprated alternator? are you fitting the right size main fuse?

doesnt seem possible to me but seems like you are simply drawing a lot of current through all your lights being on and the alternator is putting more back in than the fuse is rated at

leave your lights on for a while with the engine off and then start it up so the alternator is charging flat out and see if it blows, if you have a multi meter see what the battery voltage is at the time, if its up around 13.8 to 14.4v I could be right, if its lower than that it could be something else, if tis higher than that your alternator is stuffed anyway

[smileysmoke]

go past an auto sparky and they will test it for you also.
i dropped by one and he had a trolley with a big multimeter looking thing on it

[St Jimmy]

check the plugs under the dash mine did the same thing but ended in a fire i had to get a new harness and put in still fixing the fire damage up it's more likely the main plug shorting out

[Cypher]

Well, it seems to be fixed. I put the interior back together and taped up the loom, but instead of using the stock alternator wire I've run a 8ga wire directly from the terminal on the alternator to the battery. Took it out for a decent run with plenty of high revs and all lights on and didn't have any problems



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