Tail Light Switch

Lighting Switch (Tail Light Switch):

The Tail Light Switch, located in the lighting switch on the steering columns left stalk, is used as one of two grounds to complete the circuit for the idle up relay. To test the Tail Light Switch, Proceed as follows.
1. Insure that the Tail Light switch is in the "off" position, and the blower fan switch is in the "off" position.

Connector M54:

2. Disconnect the connector to the idle up relay (relay M54, located in the relay box, behind the knee bolster on the lower left side of the dashboard) and test terminal 3 for continuity to ground. There should be NO continuity (infinite ohms). If there is continuity, go to step 6.
3. Place the Tail Light Switch to the "on" position, there should be continuity.
4. If all the tests to this point are good, the Tail Light Switch is functioning properly.

Connector M50 Location:

Connector M50:

5. Because of the common connection in the wiring harness, if continuity is found on step 2 (with the blower fan switch and the Tail Light switch "off"), then the Tail Light switch must be disconnected (connector M50) and tested (terminal 16) separately from the wiring harness.
6. If the Tail Light switch tests good, test for a faulty blower fan switch or a grounded wiring harness.