Test Notes

Normal Operation
The diagnostic monitor measures the resistance between pin 21 (Circuit 620, P/LB) and pin 3 (diagnostic monitor reference ground). It the diagnostic monitor measures a difference of more than 2.0 ohms between pin 21 and pin 3, it will flash out code 45.

Note that Circuit 620 (P/LB) is attached to the side of the center radiator primary sensor case. In addition, the case is grounded to the vehicle.

Possible Causes
High resistance on pin 21 (Circuit 620, P/LB) to ground can be caused by:
1. A poor connection due to loose mounting, dirt, or corrosion at the crash sensor mounting location.
2. An open or damaged wire in Circuit 620 (P/LB) from pin 21 of the diagnostic monitor harness connector to center radiator crash sensor. This includes splices and in-line connectors.
3. An open wire or loose (Circuit 620 P/LB) wire attachment inside center radiator crash sensor.

Note that Circuit 620 (P/LB) is spliced into another wire going to Pin 22 of the Diagnostic Monitor. Note also that Circuit 620 (P/LB) passes through an in-line connector between the main instrument panel harness and the engine compartment harness that connects to the center radiator primary crash sensor.