Only when the key is fully pulled out, the ignition is switched off an engine stops. In the display there's a message with a yellow key symbol (and a yellow triangle at the bottom) saying something like "Engine Start System Fault, contact workshop". The car is drivable and seems to work, but the ignition remains "on" (and engine running, if started) until key is pulled out.

 

The issue is only when trying to switch "off", when switching "on" all works normal (besides of the error message). The issue is permanent and came suddenly. Battery is quite new and charged.

 

I have:

• Checked with VCDS, and module 09 says fault "B12E6 Terminal 15, short to positive".
• No error codes in steering wheel electronics (that includes the ignition key lock, I think). And no other fault codes at all.
• Checked ignition relay J329 that switches the KL15, and it is working. Both on the test bench and in the car - but seems to still have coil power (from J519 ?) even when key has been turned to "off".
• If I, when switching on, not turn the key all the way to the mechanically steady "on" position but only as far as ignition has switched on and hold the key in that position, it will go off as normal as soon as I release the key and let it return to "off". But as soon as I have turned it far enough to reach the (mechanically steady) "on" position, ignition will stay on regardless of what I'm doing. Until I remove the key from the ignition lock.
• Performed a power reset, i.e. disconnected and reconnected the battery. No difference
• Checked signals associated with KL15/ignition on module 09, and I can see that one of the four followed the key position and always changed from "active" to "not active" when key is turned to "off". Looks like it still could understand the key correct position....
• Also checked signals associated with ignition key lock at Steering Wheel electronics. Both followed the (faulty) ignition status and said "enabled" until I fully removed the key. But I don't know if this test is relevant at all, not 100% sure about the monitored signal impact on the function.

 

I really don't know how to proceed. Any ideas ?

Edited 27 October, 20241 yr by Ingper

21 minutes ago, Ingper said:

module 09 says fault "B12E6 Terminal 15, short to positive".

So module 09 is seeing the ignition switched terminal as unswitched.

 

I would check against a wiring diagram where module 09 gets its ignition switched feed(s) (there may be more than 1) from and get tracing with a multimeter.

27 minutes ago, PetrolDave said:

So module 09 is seeing the ignition switched terminal as unswitched.

 

I would check against a wiring diagram where module 09 gets its ignition switched feed(s) (there may be more than 1) from and get tracing with a multimeter.

But it is really unswitched (or at plus level when it shouldn't), because the ignition/KL15 relay J329 is still enabled (controlled by module J519).

 

And I'm afraid the ignition key switch information is sent by CAN, from Steering wheel module (J527, that has no fault codes). Not easy to measure:

 

 

 

Edited 27 October, 20241 yr by Ingper

Problem solved !

 

If anybody else will have the same issue and find this thread, I post a follow up.

 

Some people with exactly the same problem has got the transponder antenna ring at the key hole replaced. I also tried that, but it wasn't the problem.

 

The issue was the ignition switch electronic - copper powder from the worn PCB seems to have been stucked in the space between to sections with a short circuit as result:

• The name/text of the DTC (module 09) seems to be used for many ignition/KL15 related failure, and is somewhat misleading in this case ("KL15 short to plus")
• It was not KL15 that is short to plus that was the root cause (it was the result), it was the key position "ignition" signal (not power) from ignition lock switch that seems to be present ("to plus") in a forbidden combination with other key lock signals, and then triggers the DTC
• Steering wheel module, that is the module that receives the signals from key lock switch, will not recognize any problem, because it has not the whole picture I think.
• By comparing the ignition key lock related "measured values" (VCDS) of Steering Wheel module to another (functional) similar car, I realized that it was something wrong already at the signal output from the key lock switch (although that module didn't recognized it was anything wrong)

The electronic switch unit is possible and easy to replace as a separate part of the key lock (some homemade tools needed at the arrows to release the locking tabs):

 

Disassembled the switch unit and as can be seen there is a lot of "dirt" at some isolating spaces between the sections, "dirt" that was found to be somewhat conductive:

Edited 1 November, 20241 yr by Ingper