Electrical gremlin

[AndyP]

Which relay, under the steering wheel, can kill power to the whole system?

Here's the reason for asking, couple of weeks ago I went to the car and it was dead, no lights on the dash, nothing. I pulled the rear seat out to check the battery cables and they were OK, I went to try it again and it fired up as normal. Having experience similar syptoms in the A6 I guessed at a faulty ignition switch. When I pulled it out I found this



exactly the same as the A6, so I figured a new one would cure it. Fast forward to today and it's done it again. I switched it on to lower the window, the power came on and as I hit the window switch there was a click from under the dash and all power went off. Whilst poking around under the steering wheel I hear another click and power is back.

Now I can't make it do it again so I can work out which relay it is!

[Error404]

Could be the X contact relay that cuts power during cranking?

[UrS4boy]

Load Reduction Relay (J59/"213&quot and what can be affected when it fails

Could be the X contact relay that cuts power during cranking?

That would be the J59 213 "Relief Relay" (sometime a "111") shown here behind the spare fuse holder in Position 5.





213 = 443951253J



Or it could be a 111 = 357906381B



REFERENCE: Load Reduction Relay (J59/"213") and what can be affected when it fails

http://forums.quattroworld.com/s4s6/msgs/300411.phtml

[Mikes2]

does the car have a factory alarm / immobiliser ?

If so, there is a relay under the dash for that

[mdz]

... or aftermarket alarm?
X contact relay feeds power-hungry consumers such as headlights, heater bower, e.t.c. Car would run fine without it.
One thing that aftermarket alarms cuts off (depending on installer) is the ignition. Without ignition car won't start, nothing will light up in instrument cluster and power windows won't work after you open drivers door.

[AndyP]

No alarm or immobiliser, that I know of, if the load reduction relay fails surely the car would still crank? This is like the battery has been disconnected. Whilst it was dead I pulled the connector off the back of the ignition switch and that had no power to it.

[cooperquattro]

Check the terminal on the fuse box where the main power cable from the battery attaches,it powers the complete fuse board and car

[GazzaG60]

had this in mine when i had a bad battery earth during the build. it was as if it tripped out. disconnected then reconnect after a minute or so and all was good. replaced battery earth cable and all was good.

[AndyP]

Check the terminal on the fuse box where the main power cable from the battery attaches,it powers the complete fuse board and car

What is inbetween that connection and the feed to the ignition switch?

[AndyP]

Finally fixed this last night, after much head scratching and wire tracing, it turned out to be something that I'd done, and checked a few times before

When I re-located the battery to the rear I used an Avant battery cable that needed shortening, and it was the crimp on the battery end that was loose! It was literally moving by only a fraction of a mm, but enough to break the circuit.

I've re-crimped it for now, but I'm going to get an auto electrician to do it properly at some point.

[LHD_Kid]

Nice cheap fix then....

Glad its sorted...

[AndyP]

It's sort of a blessing in disguise because some time in the near future that ignition switch would have failed and left me stranded somewhere!

[Error404]

I've got a big *** battery terminal crimp tool here mate

[LHD_Kid]

Stupid question I'm sure... how easy is the ignition switch replacement?

I feel I should do mine - as a precaution rather than necessity... would you happen to have a part number too (I'm looking on 7zap but I'm a little unsure )

[AndyP]

It's dead easy, I followed the write-up that Dave did for the S4/S6 as the S2 is essentially the same, I'll find the link and part number when I get home