Diagnostic Module Fault

Fault Source
1. Faulty LED.
2. No supply to diagnostic module.
3. Diagnostic module not grounded.

Action
1. Connect test lead to socket 5 on diagnostic module B, then turn ignition switch to On position.
2. Press test button on diagnostic module A. LED should light when button is pressed. If LED does not light, proceed as follows:
a. Turn ignition switch to On position, then disconnect connector from under side of diagnostic module A.
b. Connect a voltmeter between ground and socket 4 in diagnostic module A. Voltmeter should indicate battery voltage. If reading is correct, check ground terminal as described in steps 2c and 2d. If reading is incorrect, check fuse 33 and associated wiring for open circuit.
c. Turn ignition switch to Off position, then disconnect connector from under side of diagnostic unit A.
d. Connect an ohmmeter between ground and socket 8 in diagnostic unit A. Ohmmeter should read 0 ohms. If reading is correct, repeat test with new diagnostic unit. If reading is incorrect, check ground terminal and wiring for open circuit.