Head unit install - How i almost started a fire!

[mike_nofx]

Just thought id share this, so it doesnt happen to anyone else.
I know i farked up, but it was a simple mistake.
Ive installed plenty of stereos, alarms etc.

Anyway, i was replacing the factory GQ unit with a mp3 player, what i did was cut off the harness of the factory unit so i had access to the wiring to solder in my new harness.
I identified and connected constant 12v, acc 12v, the 4 speakers, and the earth (or so i thought it was earth!)

The earth/body wire i found using a continuity test to the body.

Anyway i have my stereo all up and running no probs at all. I drive the car and realise the tail lights dont work... it blew the 15a fuse. Didnt think much of it, but had no spare 15a so i (stupid mistake!) fitted a 20a fuse temporarily until i get to the shop. what harm can an extra 5a do!

Turn lights on to check and almost immediately the cabin begins filling with smoke... oh shit!

I realised what i had done at this point, I had connected my stereo earth to the lights wire! (the wire that dims the stereo display when lights are on)

The lights wire is earth/body when the lights are off (confirmed with multimeter, and the fact the stereo worked with the lights off!) and 12v+ with lights on!! strange, but i have heard of this system before, i dont think they are all like this.

anyway, the only wire that was damaged was the earth wire of the stereo, it was basically stripped down to copper the entire length, to the internal circuit board. The existing wiring of the patrol is undamaged, it was thicker than the headunit wiring.

Had to remove the wire from the circuit board and solder in a new one.

Anyway, thats my stupid mistake, hope someone else can learn from it!

[RN]

Pictures?

[404HZS]

had a mates ford laser do that!
replaced a blown 15A fuse with another 15A fuse and was driving down the highway when smoke started pouring from under the dash and we immediatly pulled over to find that the fuse hadn't blown but had caught on fire!!!!

[Dooley]

Haha. Nice one!

It's a good idea to actually check that the wire you're using for ground goes to a decent connection to the chassis regardless.

[-Scott-]

Haha. Nice one!

It's a good idea to actually check that the wire you're using for ground goes to a decent connection to the chassis regardless.

I did something like that at work.

New machine, first of it's kind in the country, customers arriving from interstate for training on Monday, and it's not working properly on Friday afternoon.

While troubleshooting the problem on Friday night, I hooked up a CRO to look at motor pulses (PWM DC motors). Not paying attention, I hooked up to what looked like a signal ground, but of course it was through the motor to ground.

Blew a driver on the motor control board - with no spares in the country. Switzerland could get a spare part to Australia within 24 hours - but it would take up to 3 days to get through customs.

We found a workaround - and then found the problem & fixed that too.

[BadMav]

I installed a second hand cd player, amps, speakers and subs to a mate's car once and couldn't work out why the radio would work and as soon as the cd went in no sound. I opened the unit up and checked for burnt out circuitry and found nothing. 6 months later it got the better of me and I pulled the unit out again and it dawned on me the blue remote wire I used to turn the amps on was the aerial motor wire, unlabelled and exactly the same as the remote wire. It now has a label on it for next time.