Hello
TL;DR -- keys that cause immobiliser faults may be fixed by re-soldering the joints on the components.
I have a 2002 172 (non-ESP) that's been suffering badly with immobiliser problems. Symptoms steadily got worse -- on key turn the immobiliser flashed quickly, but if the remote button was used to lock and unlock the doors the car would start. This was occurring with both my keys, so I figured they both couldn't be bad. As time passed the lock-unlock trick would not work and the immobiliser light would go solid. It then was a game of roulette which key-turn would work, and it could take up to 30 minutes.
Based on info from here I learned the immobiliser light going solid meant a hardware fault. I changed the crank sensor and checked the loom for broken wires but found none.
The last time I got stuck I was in a petrol station. After 20 minutes I pulled the key apart and wiggled all the components on the circuit board, and the car started. Aha.
So I got the keys, pulled out the circuit boards and re-soldered all the components. By that I mean I just used a small electronics soldering iron to re-melt each joint of the components. (Only do one joint at a time so the devices don't move or fall off, some are really small.) I did this on both my keys, and the problems are now completely solved.
I mentioned this on the OzRS forum and somebody else re-soldered one of their broken keys, and it now works perfectly. My car has been faultless for over a week.
Hope this helps.
TL;DR -- keys that cause immobiliser faults may be fixed by re-soldering the joints on the components.
I have a 2002 172 (non-ESP) that's been suffering badly with immobiliser problems. Symptoms steadily got worse -- on key turn the immobiliser flashed quickly, but if the remote button was used to lock and unlock the doors the car would start. This was occurring with both my keys, so I figured they both couldn't be bad. As time passed the lock-unlock trick would not work and the immobiliser light would go solid. It then was a game of roulette which key-turn would work, and it could take up to 30 minutes.
Based on info from here I learned the immobiliser light going solid meant a hardware fault. I changed the crank sensor and checked the loom for broken wires but found none.
The last time I got stuck I was in a petrol station. After 20 minutes I pulled the key apart and wiggled all the components on the circuit board, and the car started. Aha.
So I got the keys, pulled out the circuit boards and re-soldered all the components. By that I mean I just used a small electronics soldering iron to re-melt each joint of the components. (Only do one joint at a time so the devices don't move or fall off, some are really small.) I did this on both my keys, and the problems are now completely solved.
I mentioned this on the OzRS forum and somebody else re-soldered one of their broken keys, and it now works perfectly. My car has been faultless for over a week.
Hope this helps.
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