Ugh Head Unit will not work!

[jackjohn13 10+ year member]

Hey everyone this is my third post about my on going issue with my 98 vw golf. I bought this car from my friend who had previously had an aftermarket radio that was working. However he lost his license and decided to pull all 4 speakers and the head unit out. So i purchased the care with 4 speaker holes and a gaping hole in the dash where the radio was. I already had my whole audio system from my last car which i had successfully installed myself. So this was my second time installing this same head unit. My trouble started before i spliced anything at all. The radio harness was tucked in the hole so when i went to pull it out the live wires touched and sparked. My last post had some good responses about fuses and all that good stuff, however now i have checked all of the fuses with my little tester and they are all good. Im just so confused as to what could have heppend if it wasnt a fuse. Is it possible that i fried the cars wiring harness? Or could the harness adapter from the audio store have failed? Im just baffled by what could have happend and i dont have the $300+ for a new wiring harness to be installed. Any information would be highly appreciated. I need this headache to go away! Thank you to everyone who read through this book i just wrote.

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[keep_hope_alive Premium Member]

hi there. if you saw a spark, then a fuse popped.

step #1: always disconnect battery negative before working on electronics.

step #2: undo his installation. you can't trust work performed by someone else, and since you had a problem when moving wires, his install was very poorly done.

step #3: derive new sources for ignition and battery and ground, these can be separate from the vehicle wiring.

this is how i bypass vehicle wiring with a simple tap of an ignition wire:

rewire speakers - run new wiring and make all new terminations. remove any wiring the previous owner installed.

solder and heat shrink/tape all connections. crimp if you cannot solder, but buy a nice ratcheting crimper so you know they are done right. never rely on tape and twisted wire as a connection.

when testing the fuses, did you test both sides of the tabs?

a test light is not a good tool. a DMM is a minimum requirement for automotive testing/troubleshooting. you need to measure voltage and resistance. i use my DMM to measure resistance of all wires before making final connections. i look for short circuits between the wires and also to ground.

 

[jackjohn13 10+ year member]

Thank you for the response. Ive always unhooked the negative before doing any electrical work. This is the first time i didnt and look at the mess it got me into. Now as far as that diagram goes does the image in the middles represent the head unit? I know that question makes me look really dumb, ive just never had to go further than matching my HU harness with the cars harness. On top of that what guage wire would i use?

 

[jackjohn13 10+ year member]

Now that i re read that i believe the square represents the ignition wire. Which makes more sense to me. So scratch my last post which makes me feel dumber reading. Where do i find that wire and whats the process you use to make those connections. Im really not as dumb as i sound haha just a bit confused.

 

[jackjohn13 10+ year member]

I also just whent and checked if the cigarette lighter outlet worked (it doesnt). I know they are connected to the same circuit. So i there has to be a short. But like i said according to my little tool and visual inspection that fuse is fine?!

 

[>>SQL<< 10+ year member]

his diagram is of a RELAY.

Try changing the fuse for the stereo / lighter anyway.

 

[keep_hope_alive Premium Member]

yes, the square is a standard BOSCH/TYCO 5-pin relay.

Red = switched ignition wiring

Yellow = constant battery wiring

Black = ground wiring

with this relay, you can tap an igntion wire anywhere in the vehicle without worring about adding load (you should fuse for the wire used - or 1A is fine)

I agree the fuse should be changed. There are two ways to test a fuse, and both require a DMM.

1. measure VDC on both sides of the fuse tabs

2. remove fuse and measure resistance between tabs