2006 Golf TDI, crank but no start.

I'm pretty sure the speed sensor and crank sensor I mentioned earlier are one in the same.
Try wiggling the attached cable.

ya, speed sensor = crank sensor. and some flaw in that system (faulty, loose, distance too far, wire problem) could easily give a no-start

To many different modules involved.
I'm think bad ground somewhere.

If the ground under the battery case is bad then everything that grounds to the body is bad.

OK, just thought I'd update this.


Still haven't determined the exact cause. The large wiring duct running from under the engine to the top and containing the sensor wires in question was very brittle and it basically shattered when I pulled on it a little to I broke it all up, cleaned all the wires and put new tape and ducting on it.


It made it look pretty but we had another no-start episode a few nights ago that resolved itself after about 10 minutes so there was no chance for additional diagnostics.


If I was guessing, I'd say I'm getting one failure for every 100-150 starts.

Sounds like the wire strands are broken.

Another update, and maybe a breakthrough.


I took it out to a friend's last night, about 17 miles, 88F ambient, AC on.


I stayed there for a couple hours and when I came out, it wouldn't start. I grabbed my can of freeze mist and sprayed the transmission speed sensor and it started instantly!


Now, the down side is that I had to disturb the wiring harness to get the can in position to spray to there's a chance that wiggling the harness actually got it to start.


Will try this again and be more careful next time.

Long shot.
Did you slam the hood closed and then it started?

I had trouble years ago in the winter with a crank but no start.
It was the ASV sticking closed after the prior shutdown.

The engine fluttered slightly then spun fast.
Don't remember how I found it but there was a thread mentioning it.
Cleaned the inside where the flap is and no more trouble.

wonneber said:

Long shot.
Did you slam the hood closed and then it started?

I had trouble years ago in the winter with a crank but no start.
It was the ASV sticking closed after the prior shutdown.

The engine fluttered slightly then spun fast.
Don't remember how I found it but there was a thread mentioning it.
Cleaned the inside where the flap is and no more trouble.

Click to expand...

No, I had the hood open when it started.


I blew my scientific method out of the water in my haste to spray the sensor by jamming the can down into the mess of hoses and wires. I'll have to secure a longer spray hose for next time.


The ASV on this car failed VERY early in the car's life and was replaced under warranty.

Hard to diagnose a 1 in a hundred occurrence. My money is on bad wire or connect.
I had an issue with the IP that turned out to be a small nick in the wire insulation, looked like it came from the factory, only failed after 6 years. Passed continuity, but couldn't carry the necessary current, took me a very long time to diagnose.