Hello everyone. I've got an electrical gremlin running around in my car and I'm hoping someone can help me out.

First off, the car is a 2000 coupe A4 with 75,000 miles. All stock.

The issue started a couple mornings ago when I went to go to work. I turned the key on and the gauges did their sweep. As soon as I hit "Start", I heard a pop (kinda like an electrical arc or a big relay) and all the gauges / lights went black. It was like I had no battery.

So I turned the key off. As soon as I did that, I hear relays from all corners of the car start to cycle on and off quickly. The gauges, radio and interior lights were turning on and off right along with the relay cycle.

The strange thing (to me anyway) was that if I put the key back to "On", the relays would calm down and everything just stayed off.

So, here's what I've done so far...
1) checked the battery (12.5v) and cleaned the battery terminals (they were dirty)
2) checked the continuity between the ground terminal and the chassis ground.
3) checked the continuity between the power terminal and the B+ post up by the under hood relay panel
4) pulled the ignition switch and checked it per Bill Curlee's post here. If I did it correctly, everything seems to be fine with the switch.

This weekend I was thinking of going over all the ground points I can find and checking / cleaning them.

Anyway, I was wondering if anyone has experienced this before or had any tips?

Here are a couple of videos of the issue. If you turn up the volume you can hear the relays cycling on and off.

Any help or ideas would be appreciated.

Thanks,
John



http://s301.photobucket.com/albums/n...t=dscf2496.flv



http://s301.photobucket.com/albums/n...t=dscf2497.flv

 

I saw this last night but no one's responded to your post. It sounds like you've done the correct things so far. I suggest that you check the battery to starter connection as the main power for a lot of things goes through there. Don't forget that its hot. Also, I strongly suggest that you send a PM to Bill Curlee as he might have some additional insight. From the video, it looks like you are getting nothing at all. Asking the dumb things now.. have you personally checked with an ohm meter, each and every fuse in the car in both fuse compartments? There is an important ground connection between the engine compartment fuse box and the battery, down low.... needs to be looked at.

 

Hi David. Thanks for the suggestions, and I'll PM Bill tomorrow after I borrow a service manual and make sure I checked all the grounds.

I just got done checking the starter connection, all the fuses and all the grounds I could find under the hood. All the fuses and connections checked good with the ohm meter (The battery to starter read 0.3 ohms, but I think that's still good????). Everything looks clean and all the connections were tight.

The ground from the fuse box you mentioned ... Is that the small black wire coming from the bottom of the fuse box that runs to the chassis ground that is in the front left corner of the battery box area? If so, the wire and connection looks good, but I couldn't figure out where the other end of the wire was. Anyway, I pulled a relay and there's continuity between the ground pin of the relay and the battery ground wire. Is this a valid way of checking the fuse box ground?

So, the plan for tomorrow is to bring the battery in to get tested. And after that, a bunch of reading in the service manual to try and figure this thing out.

If anyone has any other suggestions, please let me know.
Thanks,
John

 

WOW! Thats a weird power issue.

You need to do some checking with a Volt meter. When you turn the key to ON, the fuses below get powered. There should be BATTERY voltages on these fuses:

Ok,,,here are the fuses that your going to check:

Under Hood Fuse Center

ENG ING1 FUSE# 19

INJR 2 FUSE# 18

THROTCONT FUSE# 17

INJR 1 FUSE# 22

PCM FUSE# 16

F/PMP FUSE# 13

Instrument Panel Fuse block

BTSI BU Fuse# 21
BCM 13 Fuse# 22

The starting circuit looks like this:



Check the main points for correct voltages


BC

 

Thanks for the suggestion Bill.

It turns out that as soon as the battery is loaded, the voltage drops to 7v. Of course this isn't enough to run most of the electronics, so everything shuts off. As soon as everything shuts off, the voltage goes back to 12.5v and everything tries to turn back on. So anyway, I put a new battery in and everything is back to normal.

Thanks again Bill and David for the help.
John

 

Glad you figured it out. Lots of batteries give up when winter temperatures start setting in.