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Cardoctor71
Cardoctor71, ASE Master Technician
Category: UK Car
Satisfied Customers: 670
Experience:  35 years experience in the automotive and Lt truck repair business, owner Cardoctor LLC Guthrie, OK
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This has been a running saga to get my 2001 Sharan started.

Customer Question

Hi all,
This has been a long running saga to get my 2001 Sharan started. (VIN: WVW ZZZ 7MZ 1V02 8968)
Short version:
-Replaced a blown cigarette lighter fuse.
-Car won't start (doesn't turn over)
-Starter itself starts the car when jumpered directly from the battery.
-Replaced 175 relay
-Replaced control unit box underneath relay panel.
-Still no luck...
Looking for the next thing to try before giving up. Ignition switch, possibly?
Long version:
Let's start at the beginning...
One of the kids put a coin in the cigarette lighter and blew the fuse. I found the blown fuse (#7). I replaced it with another identical 25 amp fuse from #12 that seemed to be for the rear defroster (or some other not so important thing). Now the car won't start because the starter won't turn over. I've since put all fuses back where they should be.
I did some diagnosis, and found the following. I should note that I've never attempted to diagnose anything like this before.
-All fuses seem OK (looked at the ones under the dash and in the engine)
-The relays are secure, but I didn't test them. Some of them are 9-pin, and I'm not entirely sure how to test these complex ones.
-The plug to the starter solenoid gets no voltage when I try to start the car. I tested with a multimeter.
-The starter is good because I can direct-wire into the solenoid, and touch it to the positive terminal of the battery (with key turned on)... car starts right up like a charm.
-The battery is obviously good.
-On a hunch, I replaced the 175 relay. This solved nothing.
-The glow plug light comes on when I try to start the car. I've read that a bad 109 relay could cause this light to not appear (and not allow fuel from the pump)
-I hear the fuel pump priming when I attempt to start. Well, and the engine runs fine once hot-wire started.
However, when I drive it, the following things don't work:
-Transmission doesn't shift (seems to start out and stay in 3rd gear)
-Left blinker doesn't work
-Speedometer (tacho) doesn't work.
I limped it up to the VW dealer (I live in Switzerland), and after 200 francs of "investigation", they told me I needed a new "central control unit". It's basically the control unit that sits under the dash where the relays are. OEM number is *****
Well, they said this would fix it, but they wanted 3500 francs for it! I immediately went to a breaker on ebay and bought a used replacement from Germany for little money. I replaced it tonight, but still the same problem. Car still starts when I "hot-wire" the starter, though. However, now my key fob no longer electronically locks the doors. Possibly this needs to somehow be programmed with the key? Maybe I'll put the old one back in.
I don't know if the dealer hooked up a VAG-COM, or whatever they have there, but I didn't get any codes from them. I cracked open the case of the supposedly bad control unit, and visually it looks fine. I'm not sure how they came to the conclusion that I needed a new control unit. I can't spend a lot of money on a car that isn't worth that much on the books.
My question is... What should I try next? Here are my thoughts on options:
1. Replace every relay (there are 12 or so of them). Is there a specific one I should target first (note that I already tried replacing the 175).
2. Take it to an independent mechanic and pay up, however, I'm quite determined to fix it myself.
3. Could it be the ECU (the one behind the battery) by any chance? From what I read, the ECU generally won't affect starting issues.
4. Could it be the ignition switch? That seems fairly simple to replace.
Submitted: 1 year ago.
Category: UK Car
Expert:  Cardoctor71 replied 1 year ago.

I am suspecting you have wiring damage leading to the cigarette lighter wiring harness rather than a component failure, all kinds of crazy things can occur when a coin gets put in a cigarette lighter, then once the electrical issues are remedied you will need to reinitialize ALL COMPUTERS, IN ORDER TO FINALLY GET THE CAR TO START. You will need an accurate wiring diagram to identify the affected secondary circuits that may have beeen damaged prior to the fuse blowing, you will also need sufficient knowledge and time to be able to remove whatever is necessary to access the damaged wiring and make repairs.Please RATE my service a 3 or above, if for some reason you can not, Please ASK me another question, i will continue to answer your questions even after rating is given, until you are completely satisfied with my answers.