FSI 2.0 auto no crank

Partner's 2005 Golf BLR is not cranking but when I jumper the solenoid S terminal to battery + the car cranks and starts. Put a multimeter on the solenoid trigger wire from the ignition switch and 0 volts when cranking, but 5 volts when not cranking. Weird.

Figure it could be a fault with the ignition switch itself or the alarm / immobiliser or the neutral / park switch. Anyone know whether the ignition start signal has a relay and where it is? Also, where is the alarm relay and neutral / park switch or relay located? Is there a connector close to the ignition switch where you can back test it? Thanks.

I wanted to move the car from the street to the driveway yesterday and I tried to start the car again by jumpering the solenoid wire and it turned over but didn't start. I kept trying and must have tried too many times too quickly and I think the starter motor is now fried. :facepalm:

Then I did a scan with VCDS (saving then clearing all previous codes) and 09:Cent.Elect. reads "no fault code found", same for 25:Immobilizer. This surprises me - how can you clearly have an electrical problem and the scan not pick it up? There were faults found in 01:Engine of EGR, TPS, Angle sensor, Intake air temp and ABS but I wouldn't think these would cause a no crank situation.

The previous scan showed this in 09:Cent. Elect: 01516 - Terminal 30 left [and right] 011 - open circuit, priority 1. My searches so far seem to indicate this as a headlight fault but I'm still searching.

Thoughts?

I took the starter out again today and it only took me 1 hour verses 4 hours the first time. Tested it again and yes its fried. The weird thing is I tested the ignition to solenoid wire again before I removed the starter and it now has 12.3 volts! Where did that come from? All I did was erase the old fault codes, do a new scan and renove and test realy #100 in the engine compartment fusebox, and relay #51 behind the interior storage compartment. Maybe its an intermittant fault so I would still like to find out about the starter relay etc. Might eventually have to go to that erWIN online manual which I find difficult to navigate and hate.

I installed a new starter motor yesterday (bought new for $220 which is alot better than the $1000 quoted by the dealership) and the car starts and runs perfectly. Not sure what the original cause was - an intermittent fault in the starter motor which eventually failed or maybe an intermittent fault in the ignition switch which is yet to return. I'll just have to wait and see. I learned that the problem definitely wasn't the immobiliser which is showing the "key recognised" symbol in the cluster when I insert the key.

Glad you got it sorted.
Mine failed many years ago. Sometimes slow, then not at all. Initial diagnosis by RACQ was a bad battery. Replaced battery but 5 days later no crank while at the servo.

Thanks. Yes its a relief. I also called the RACV early on as I thought they might help in diagnosing the cause. He only tested the battery and said it was ok and declared its therefore the starter motor - no trying to jump start the starter motor from the battery which I also had forgotten about. At that stage the starter motor was still working I later found out. I think I'll keep a length of wire in the car just in case.