B6 S4 cranking issue - starter motor?

[Error404]

Got an odd intermittent issue with the S4 at the moment.
Sometimes it refuses to do anything when the key is turned in the ignition - no cranking or anything. Other times is starts first turn - never any issues starting it running once its actually cranked... but very hit and miss. Can't hear the starter solenoid firing or anything when it refuses to crank, so my thoughts are towards starter motor. Anyone got any ideas on how to test this?

Cheers
Alex

[mcandmar]

B6 is one of those new fangled A4's right? In my experience with modern VW/Audi stuff its electrical, either switch on the key or a relay somewhere. Even if the starter motor itself was bad you will have other visual clues like accessory's turning off when in the start position, or lights dimming if its got a dead short etc. The fact you say nothing happens implies to me its not seeing the signal to start, or its just ignoring your input due to immobilizer or something not working properly.

I worked on a TT last weekend, brake pad wear indicator stuck on, and interior lights no longer working. Cleaned the contacts for the brake pads indicator and the interior lights starting working again. Thats the kind of electrical voodoo you can expect from modern VAG cars..

[Error404]

Cheers Mark

Sorry I should also say it cuts the 12v to all non-essential systems as expected, just doesn't crank.
Will pull the codes later and see if it shows anything. I'd have thought the only other explanation could be immobiliser related?

[andy10v]

I would guess at ignition switch.

My crude way of testing a starter is to feed it 12v with a jump lead and see what happens.

You can use a lighter cable to the engagement solenoid to see if it throws out etc (if it works the same as older ones)

Check how the immobiliser works, on a b5 a4 it fires and runs for 1 sec before cutting out.

I worked on a TT last weekend, brake pad wear indicator stuck on, and interior lights no longer working. Cleaned the contacts for the brake pads indicator and the interior lights starting working again. Thats the kind of electrical voodoo you can expect from modern VAG cars..

WTF? Common earth?

[stocious]

Check to see 12v on signal wire, is it easy to access?

[LHD_Kid]

Stinks of an immobiliser issue to me.... unless it hasn't got one fitted...

[4WheelDrifter]

Check to see 12v on signal wire, is it easy to access?

^^^ Do this first.
There should be a single 12v feed to the solenoid. Get a mutimeter on it and get an assistant to turn the key.

[Error404]

Access to everything is difficult on the V8
I'll have a go and see if I can get to it, seem to remember it being well tucked away behind the engine mount.
Sods law dictates when I come to test it, it'll start first time

[stocious]

Access to everything is difficult on the V8
I'll have a go and see if I can get to it, seem to remember it being well tucked away behind the engine mount.
Sods law dictates when I come to test it, it'll start first time

Follow the conduit back from starter and there's a plug to make it easier to remove starter " wires on" test at the plug if easier!

[4WheelDrifter]

You need to check that the starter is getting a signal.

I had an intermittent non-starter problem with the A3 a few years ago, as you describe. The wire had rotted off at the connector at the starter. A quick cable strip, a new terminal pin, and it was fixed.

Last month the starter failed again. This time the cable that goes from the solenoid to the starter had rotted. A short 50 mile trip to the nearest ECP and back for a new starter, a few basic tools that I had in the car, and about 30 minutes work in the snow and the job was done.

[Monkeymagic]

I've seen this on couple of b6 a4. both times it was the starter. they would do nothing first cycle of key then 2ne turn they cranked. once warm would always start. possible dirty contacts and swapping them cleaned things up?

[Error404]

/\ Only does it from stone cold, if its been run within 24 hours it starts perfectly first time.

I'll have a look at the wiring and test it if its dry next day off I get

[stocious]

Would be nice if you could give solenoid a little tap with something when it's not working. If there is power going to solenoid but no click, a tap usually does the trick, and makes decision on purchase easier when it's in a awkward spot. Good luck with the test's

[4WheelDrifter]

Would be nice if you could give solenoid a little tap with something when it's not working. If there is power going to solenoid but no click, a tap usually does the trick, and makes decision on purchase easier when it's in a awkward spot. Good luck with the test's

It's always worth a go, especially in an emergency. Poke a wheel brace or breaker bar down/up there.

[Error404]

no way to get anywhere near it to tap it unfortunately, that would normally be my first trick.
Just had a read som some of the yank forums and seems to suggest the starter itself it dodgy.
I'll test the connectors and wiring, if that looks ok I think i'll just replace it.