Diagnosis and testing

Turn signal and hazard warning systems

When diagnosing the turn signal or hazard warning circuits, remember that high generator output can burn out bulbs rapidly and repeatedly. If this is a problem on the vehicle being diagnosed, refer to Charging System in the Diagnosis and Testing section of Group 8C - Charging System for further diagnosis of a possible generator overcharging condition.

If the problem being diagnosed is related to a failure of the turn signals to automatically cancel following completion of a turn, inspect the multi-function switch for a faulty or damaged cancel actuator and inspect the turn signal cancelling cam lobes on the clockspring mechanism for damage or improper installation. For complete circuit diagrams, refer to Turn Signals in the Contents of Group 8W - Wiring Diagrams.

WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, REFER TO GROUP 8M - PASSIVE RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.

(1) Turn the ignition switch to the On position.

Actuate the turn signal switch or the hazard warning switch. Observe the turn signal indicator lamp(s) in the instrument cluster. If the flash rate is very high, check for a turn signal bulb that is not lit or is very dimly lit. Repair the circuits to that lamp or replace the faulty bulb, as required. If the turn signal indicator( s) fail to light, go to Step 2.

(2) Turn the ignition switch to the Off position.

Check the turn signal fuse in the junction block and/or the hazard warning fuse in the Power Distribution Center (PDC). If OK, go to Step 3. If not OK, repair the shorted circuit or component as required and replace the faulty fuse(s).

(3) Check for battery voltage at the hazard warning fuse in the PDC. If OK, go to Step 4. If not OK, repair the open fused B(+) circuit to the battery as required.

(4) Turn the ignition switch to the On position.

Check for battery voltage at the turn signal fuse in the junction block. If OK, go to Step 5. If not OK, repair the open fused ignition switch output (accessory/ run) circuit to the ignition switch as required.

(5) Turn the ignition switch to the Off position.

Disconnect and isolate the battery negative cable.

Remove the combination flasher from the relay and fuse block and replace it with a known good unit.

Connect the battery negative cable. Test the operation of the turn signal and hazard warning systems.

If OK, discard the faulty combination flasher. If not OK, remove the test flasher and go to Step 6.

(6) Turn the ignition switch to the On position.

Check for battery voltage at the fused ignition switch output (accessory/run) circuit cavity for the combination flasher in the relay and fuse block. If OK, go to Step 7. If not OK, repair the open fused ignition switch output (accessory/run) circuit to the turn signal fuse in the junction block as required.

(7) Turn the ignition switch to the Off position.

Check for battery voltage at the fused B(+) circuit cavity for the combination flasher in the relay and fuse block. If OK, go to Step 8. If not OK, repair the open fused B(+) circuit to the hazard warning fuse in the PDC as required.

(8) Disconnect and isolate the battery negative cable. Check for continuity between the ground circuit cavity for the combination flasher in the relay and fuse block and a good ground. There should be continuity. If OK, go to Step 9. If not OK, repair the open ground circuit to ground as required.

(9) Disconnect the instrument panel wire harness connector from the multi-function switch connector receptacle. Check for continuity between the hazard signal circuit cavities for the combination flasher in the relay and fuse block and in the instrument panel wire harness connector for the multi-function switch.

There should be continuity. If OK, go to Step 10. If not OK, repair the open hazard signal circuit as required.

(10) Check for continuity between the turn signal circuit cavities for the combination flasher in the relay and fuse block and in the instrument panel wire harness connector for the multi-function switch.

There should be continuity. If OK, refer to Turn Signal Switch and Hazard Warning Switch in the Diagnosis and Testing section of this group. If not OK, repair the open turn signal circuit as required.

Turn signal switch and hazard warning switch

The turn signal switch and the hazard warning switch are integral to the multi-function switch.

Refer to Turn Signal and Hazard Warning Systems in the Diagnosis and Testing section of this group before testing the multi-function switch. For complete circuit diagrams, refer to Turn Signals in the Contents of Group 8W - Wiring Diagrams.

WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, REFER TO GROUP 8M - PASSIVE RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.

(1) Disconnect and isolate the battery negative cable. Disconnect the instrument panel wire harness connector from the multi-function switch connector receptacle.

(2) Using an ohmmeter, perform the switch continuity checks at the connector receptacle terminals as shown in the Multi-Function Switch Continuity chart (Fig. 3).

(3) If the turn signal switch or hazard warning switch fails any of the continuity checks, replace the faulty multi-function switch assembly as required. If the switch circuits are OK, repair the lighting circuits as required.