98 A4 - won't start with new radio

My son wasn't happy with his factory Bose system so he has begun to build a new system.
The local 'Boomer Mcloud's' sold him a VW wiring harness and told him
that the 20 pin connector on his system was just for the CD changer- and that this harness would work. So he dilligently soldered all the wires to his new deck, plugged things in and had a deck that lit up, appeared to work, but put out no sound.
The car would start at this point.
There were a bunch of speaker ground wires from the new deck that were not connected to anything- and he grounded them to the chassis to see if that would give him sound. It didn't -- but the car quit starting. It turns over fine, but doesn't fire. It's in the driveway & it's been raining for days so I haven't even popped to hood to see if it has fire or gas.
Shortly after we saw the pinout diagrams on the old deck that showed the speakers on the 20 pin plug-- went to Circuit City- got hooked up & now he has a stereo-- but he can only listen to it in the driveway.
Any thoughts on what we might have screwed up during the install of the stereo? It seems like an unlikely co-incidence that something else failed as we were working on it. [Though it was started and turned off several times in succession as he tried different things to try to get sound from his speakers.]
Thanks, Jim Son's Car; 98 A4 Quattro
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Hmmm
Firstly he should have just got a normal ISO wiring harness for the Audi, that way no soldering etc needed to take place, as for the starting problem I would suggest it's not related but you never know, did he cut any other wires that were behind the dash?
The stereo would not normally have anything to do with starting the car, I know it is connected to the alarm so it's feasible that it is now immobilised, does the car turn over ok and just not fire? is the key symbol flashing or constantly on the dash display?
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-snip-

The soldering was all from the new deck to the harness-- I warned him not to touch the stock wiring as the 98 has some OBD stuff in it & we might need to plug the old radio back in to pass an emissions inspection.

Not on purpose, but things have been known to get jiggled loose.

Turns over fine. [new battery] But doesn't fire at all. I don't see any key symbol on the dash.
Thanks- When the rain stops [Sunday?] I'll start troubleshooting it. I was hoping it would be a simple & common problem.
Jim
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wrote:

There should be no soldering required, the new deck (kenwood/Alpine/Sony etc) all have their own ISO harness you can buy for around 25 quid ($50) you just plug that into the new deck and the 2 x plugs you pulled from the old stereo. The only problem with B5 A4's is the harness tends to be wired different so you have to reverse the yellow and red wire.

I would put the old stereo back in and start from scratch, or ask an Auto Electrician to sort it out, sounds like your son has been fiddling a bit too much :)
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-snip-

Ron- thanks. Update . . . . The rain stopped and we got to check it out. No gas was getting to the plugs. Couldn't hear the fuel pump running- so I checked the fuse. Both Bentley and the owners manual said it was fuse 28, but that one was vacant. I cursed them both out, but wasn't too surprised as the horn relay wasn't where they both said it was-- and some other fuse we had checked once was not where the owners manual said it was.
Then we pulled the relay [got the part number from bimmerzone and pulled relays to check for that part number]. The darn thing is $35 so we didn't just order one to swap out to test. While I was looking for some way to test it beyond the little diagram printed on it that shows the normal open & normal closed I remembered that my son's buddy had been checking fuses when we couldn't get the new deck to work.
Sure enough-- 27 is supposed to be rear wipers, and he doesn't have them. Moved that fuse to 28 & she fired right up.
For my son who has slightly more time than money it was a good cheap lesson on the importance of paying attention to the little things.
Jim
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