While the alarm system might be complicated the relay is not. It is a simple 5 pin relay and the easy way to test its function in the circuit is to just by pass it and see if it starts. if it does then one must decide if the alarm is keeping it open or whether it has just failed.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician