Alfa Romeo Forum banner

1 - 2 of 2 Posts

·
Registered
Joined
·
169 Posts
Discussion Starter #1
Over the years, there have been many things wrong with my car, some of which I have investigated and fixed.
I meant to post these findings as a reference in the hope that it may help someone (and myself, because after a long time I might not remember it anymore). It seems that some of the problems are not very common (but some are, I think).

Symptom: The car would just randomly not start. When it happens, turning the key to MAR does not turn the starter motor at all. I could try many times and it would not start. After while it might start again.

Cause: Previous owner had installed a relay in the starting circuit which I thought was odd. After removing the relay and reverting to the way the circuit was originally wired, all was good. Until one day it began to randomly refused to start. At the time I did not think of the link as it had been a while after removing the relay that this happened.
I had thought the starter was not in the best shape and changed to a new one. And the problem persisted.
I thought of the connectors at the ignition switch. The connection looks good but I cleaned it anyway and made sure the contact is good. But the problem persisted.

Eventually I found that it was the ignition switch after all. But the failure mode is not very obvious.
Below image is an example of the type of ignition switch used in the 156. There are a couple of types where the pin width is different but the way they work is the same. As one would expect, one of the pins carries 12V supply and another pin in there connects to the solenoid on the starter motor. When the key is turned to AVV, the connection is made between these 2 pins causing the solenoid to energize and turn the starter motor.
I suspect the current is quite high that over time the contact inside the switch is slightly degraded. Note that quite high here is relatively speaking, since the current is only the solenoid current, not the starter motor current as that is drawn with a thick cable direct from the battery.
I removed the switch and tested it on a bench with a multimeter. If I pull slightly in the direction away from the switch on the pin that connects to solenoid, then the connection is lost. If I let go or push in slightly then the connection is made again. I used the same method to test all the other pins, and there were no problem. This defect only occurs to the pin that connects to the starter solenoid!
ig-sw.jpg

Remedy: Change the ignition switch. I change to an aftermarket switch that available for low price. That failed again in short order. I managed to find a brand new original barrel with switch and swapped it over. Switch is still working as it should.
 

·
Registered
Joined
·
3,060 Posts
Thanks for the Information.

Sent from my SM-G975F using Tapatalk
 
1 - 2 of 2 Posts
Top