Fixing Chevrolet Spark immobilizer (dead k-line)

[SAMDoctor]

Hi!

I had recently to troubleshoot a dead immobilizer on a Chevrolet Spark immobilizer, did not respond to diagnostic (K-Line). It was easy to find out that the immobilizer was grounding the K-Line. I don't have a waveform for the damaged immobilizer, but I have one after the repair:

https://i.imgur.com/25phlS1.png

The K-Line stays high until the ignition switches on, then stays low for a second and then goes high again, while at the same time you can hear the relay clicking.


Pinout in this image

https://i.imgur.com/zE2JusL.jpg

[volodin69]

Nice description. But what is the main problem? Car is a nonstarter? What ecu does it have? Just asking...

[SAMDoctor]

Car doesn't start, no diagnostics, no communication with ECU nor immo....

[antonis132]

is it 1.0 spark? do you want to read flash and send immo file?

[SAMDoctor]

Yeah, 8E immo. Problem is not the MCU but the kline serial interface (MC33660). Do you need a dump?

[antonis132]

yes i can help you with immo off on ecu, just send me flash reading of ecu

[SAMDoctor]

Thanks for your offer, but repaired the immobilizer and paired a key, no issues. Just thought it was worth sharing, maybe someone would need this info in the future.

[antonis132]

did you replace a specific chip?
could you share something about the succesfull repair?

[Andrey Pribalt]

Everything is correct, the relay should operate for 2 seconds after turning on the ignition (the immo is polled via the K-line).,
The signal amplitude on the K-line is correct.
Hi!

I had recently to troubleshoot a dead immobilizer on a Chevrolet Spark immobilizer, did not respond to diagnostic (K-Line). It was easy to find out that the immobilizer was grounding the K-Line. I don't have a waveform for the damaged immobilizer, but I have one after the repair:

https://i.imgur.com/25phlS1.png

The K-Line stays high until the ignition switches on, then stays low for a second and then goes high again, while at the same time you can hear the relay clicking.


Pinout in this image

https://i.imgur.com/zE2JusL.jpg

[SAMDoctor]

did you replace a specific chip?
could you share something about the succesfull repair?

The K-Line serial interface chip, MC33660 :)

[SAMDoctor]

Everything is correct, the relay should operate for 2 seconds after turning on the ignition (the immo is polled via the K-line).,
The signal amplitude on the K-line is correct.

Yes, with the damaged K-line serial interface, the waveform was reversed.

[Andrey Pribalt]

Yes, with the damaged K-line serial interface, the waveform was reversed.

Does the immobilizer unit recognize the key?

[SAMDoctor]

It was a police auction car, no key. You couldn't do any diagnostic, as the immo was pulling the whole k-line to ground.

[antonis132]

thanks informs us with your experience