Very strange electrical problem plaguing the ol' crate

The Goodz · 31-07-2005, 06:47 PM

Hello all, isn't it great that I haven't posted on here in ages, and when I finally do, it's because there's something wrong with the bloody car? Lovely.

Anyways, just been out to glenmaggie for the weekend, and while I'm out there, we decide to go for a drive. We take off and all of a sudden all the electrics are going spastic, both volt guages (for the triple battery system) start clicking around at 10 volts, so obviously it was a short circuit. Open the boot and theres smoke around battery no. 2. It stopped when I switched the engine off, obviously because the battery isolator solenoid saw that the main battery wasn't getting charge, so it separates them. There location of the short was not clear, so I disconnected the whole triple battery setup and figured i'd fix it later. So off we go and when we go to leave from our destination, the engine starts missing and backfiring really bad, the tacho starts jumping up and down quite wildly (although the engine revs aren't moving so much, the wolf is showing the revs to be consistent and closer to 1000-2000 rpm), and also the fuel flap ajar light starts flashing. So I go back to the boot, and found that the plastic sheath around the connector of earth cable for batteries 2 and 3 was a little melted, so a pull the cable and it comes right away from the body, the connector itself had broken off somehow and must've been touching the body back and forth, creating sparks and god knows what. I pull it away, and there is absolutely no difference. It still plays up. At this stage I've disconnected the whole triple battery setup, the solenoid is disconnected, everything.

Now the wierd starts.

A few anomalies have appeared. The volt guage for the main battery (which is connected straight to main battery) reads around 13-13.5V. Normally sits at around 14V. The wolf is telling me the voltage is 14.1V, same as always.

This backfiring and carrying on and losing power thing is intermittant, it'll be alright for a few minutes, then come back on. But what I noticed is that it seems to happen after or while I press the brake pedal. Usually after releasing the brake pedal. And if it starts carrying on while I'm driving, a tap of the brake pedal seems to make it come good, at least for a little while, although the brake pedal seems to cause it a lot of the time. Sometimes while I pull up to a set of lights with the foot on the brake, the tacho will read 0 revs, but when I lift my foot off the pedal, it comes on again. This only happens some of the time. Also, if the tacho dies while pressing the brake pedal, if I indicate the tacho jumps up with the clicking of the indicator.

I have had a look round the engine bay and can't see any obvious shorts, the battery terminals are tight, and I'm certain it's not my mass of wiring that many of you have seen, because a lot of it isn't even being used. I've looked under the dash above the pedals and can't see anything obvious there either. I'm thinking it could be something to do with the brake pedal switch, as the brake pedal is definitely playing a part here.

Any ideas?

Thanks guys

Alex

Damo · 31-07-2005, 07:17 PM

I doubt a brake pedal switch would cause all that, they either work or they don't. I got about 4 of them from pik a part for $5 if you think it's worth a shot, or they're $15 new i think.

Sounds like some weird problems you got there Alex, good luck getting them sorted.

How was the old crate going before these dramas, havn't had an update in ages..?!

LUXO_8 · 31-07-2005, 07:37 PM

woah alex, thats wierd.
sounds like its all to do with the dual battery setup....
still, very wierd!

The Goodz · 31-07-2005, 07:58 PM

The ol' crate was going just fine before this, apart from a new clutch I put in the other week because the pressure plate collapsed, other than that no dramas!

I also doubt it has anything to do with the brake pedal switch, but who the hell knows, could be a short in the wiring somewhere.

Alex

ilsautomotive · 01-08-2005, 09:08 AM

I hope there hasn't been a short that has actually damaged the ECU? Is it possible to get that checked?

Other than that, bad earths can cause weird things...

The Goodz · 01-08-2005, 05:05 PM

The ECU seems fine, it wasn't actually playing up today, although the fuel flap light is still flashing, will keep searching...

Alex

The Goodz · 02-08-2005, 10:54 PM

Ok an update. For 2 days now the thing was behaving itself, no major dramas or strange occurrences, with the exception that the fuel flap ajar light still flashes. Now tonight as I went to leave from school, I went to start it and it fired up for about 2 seconds, then died, and wouldn't start again. As I tried to crank it, the car outline lights on the dash were flashing all over the place. It seemed as if there was no spark. I checked under the bonnet, all the wiring seemed fine (as fine as things seem with a torch in a dark alley). Then I remembered that the drivers door light switch didn't normally work, tonight it did. I jiggled it around, tried again and the car started. All the way home the engine didn't give me grief but the tacho would still jump around and for the most part just sit on 0, although the wolf was giving me a correct steady reading. Tapping the brake pedal would make it come good for a little while.

The plot thickens only slightly!

Alex

LUXO_8 · 02-08-2005, 11:12 PM

woah, your car is posessed.

when my door adjar thingy was flashing, shortly after my battery died....

replaced it and it was fine....

although you have 3 batteries so...........

InitialD · 02-08-2005, 11:16 PM

Quote:

Originally Posted by The Goodz

Ok an update. For 2 days now the thing was behaving itself, no major dramas or strange occurrences, with the exception that the fuel flap ajar light still flashes. Now tonight as I went to leave from school, I went to start it and it fired up for about 2 seconds, then died, and wouldn't start again. As I tried to crank it, the car outline lights on the dash were flashing all over the place. It seemed as if there was no spark. I checked under the bonnet, all the wiring seemed fine (as fine as things seem with a torch in a dark alley). Then I remembered that the drivers door light switch didn't normally work, tonight it did. I jiggled it around, tried again and the car started. All the way home the engine didn't give me grief but the tacho would still jump around and for the most part just sit on 0, although the wolf was giving me a correct steady reading. Tapping the brake pedal would make it come good for a little while.

The plot thickens only slightly!

Alex

Do you mean the car goes wierd and doesnt wanna start when it shows the door's being open? my old ladys EA Ghia was doing this, whenever the drivers door sensor would stuff up, the car wouldnt start, I unplugged the sensor and it has started every time.. i have no idea why :S and her car also shows the fuel flap open when you go around a corner

renno · 03-08-2005, 08:59 AM

Was chasing a fault with the driver's door light switch the other day, found a wire from an adjacent loom was caught under the back of the switch. It had cut through the insulation, but fortunately had not touched the switch body and shorted. You may have something like this.

The Goodz · 03-08-2005, 05:02 PM

Thanks renno, I'll try that too.

Alex