The logic module uses this relay to control power going to the fuel pump, ignition coil, fuel injectors, and portions of the power module. For 1985 - 1987 models, the relay was internal to the power module. The 1984 power module, the SMEC, and the SBEC use an external relay. The ASD relay will be activated when the logic module detects a signal from the ignition reference sensor. If the signal is lost while the engine is running or the turbo boost pressure reaches the overboost cut-off point, the ASD relay is shut off and the engine will shut down.
When the logic module is turning on or off the relay, it momentarily checks the output of the relay/solenoid driver to see if it is responding the way it should. If it does not see about 0V when on (open circuit) or 12V when off (short circuit), a fault code 42 is stored. For later models that use the SMEC or SBEC, the module will monitor the output of the relay to the fuel pump and fuel injectors. If 12V is not detected when the relay is activated, a fault code 42 is stored.
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Updated 12/17/2003.
Copyright © 1996-2003 Russ W. Knize.