Creative Diagnostics

The vehicle in question is a 2015 Tiguan. It came in with a no crank condition. The customer assumed this was an immobilizer issue and called a locksmith with ODIS to come and re-learn the keys. 

This didn't change anything.

The customer called in with a tech support request. They informed me that the locksmith "learned the keys" and it doesn't start. I asked them if the locksmith matched the keys to the immobilizer and he wasn't sure. I advised them to get the locksmith back there and, if he was ok with it, I would log in and see if the process needed to be completed. If you have ever used ODIS before, one thing it is not, is simple to use...

The locksmith agreed to come back and let me log into his laptop so I could poke around in ODIS. As I suspected, the immobilizer was half learned. I helped the locksmith to finalize the process. After completion, there were no codes left for the immobilizer. Unfortunately the vehicle still did not crank.

Seeing how ODIS was still hooked up, I asked the locksmith if I could peek around and see what I could see. I went into the KESSEY to read some data. I went into the key positions, and saw no terminal 50 (start circuit) activation. There were also no codes in any modules for missing terminal 50. 

This told me that the vehicle doesn't know the key is being pressed all the way (this is a push key car). 

The Ignition switch on this vehicle tells the steering column lock module to allow the vehicle to start. Let's take a look at the diagram for the starting circuit.

You can see that the ignition switch has 2 inputs the steering lock module. The steering lock module communicates to the rest of the vehicle over medium speed CAN bus. As there were no communication issues with the rest of the vehicle, and the lock module doesn't see terminal 50, the problem had to be the ignition switch or lock module.

If you read data, this vehicle doesn't read the ignition switch from the Steering Lock Module. Soooooo do I guess.............?

Let's take a closer look at the diagram.

I see 4 wires coming out of the ignition switch. The customer happened to have a Pico...

I had him connect a channel to each wire on the switch, it was hooked up as follows...

I'll log into his laptop, and we will see whats going on.

OK! We have stuff going on here. I zoom in a little bit...

According to the diagram, the red trace is the control for the LED in the switch. You can also see that the LED is commanded in 1/2 sec after pressing the key in.

Does this help with diagnosis? No, Let's get rid of it...

OK. Now we have the blue channel. according to the diagram, this is the ground. To my untrained eye, it looks perfectly steady. Let's get rid of that to clean this up a little more...

Now we are left with the yellow and green channels. These go right to the steering lock module. you can see they go right to ground for as long as he holds the switch to start. This lines up to how the diagram shows the switch working. 

I have seen enough. I recommended a Steering Column Lock Module, which on this vehicle is the steering column. With the column replaced and the locksmith called back in to code and unlock it, the vehicle started right up. 

This isn't one of those pat yourself on your back type of posts. I just figured I would share some creative diagnostics with you. 

Thanks for reading.

Here is the raw file 

*Diagrams courtesy of Alldata

*Memes courtesy of Google