Turn Signals: Testing and Inspection

When diagnosing the turn signal and 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, be certain to diagnose and repair the charging system as required. 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 cancel cam on the clockspring for damaged lobes or improper installation. The hard wired circuits of the turn signal and hazard warning system can be diagnosed using conventional diagnostic tools and methods.

For complete circuit diagrams, refer to the appropriate wiring information.

WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, SEAT BELT TENSIONER, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. DISCONNECT AND ISOLATE THE BATTERY NEGATIVE (GROUND) CABLE, THEN WAIT TWO MINUTES FOR THE AIRBAG SYSTEM CAPACITOR TO DISCHARGE BEFORE PERFORMING FURTHER DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE WAY TO DISABLE THE AIRBAG SYSTEM. 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(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 fused ignition switch output (run-acc) fuse in the fuse block and the fused B(+) fuse, in the relay and fuse block. If OK, go to Step 3. If not OK, repair the shorted circuit or component and replace the fuse(s).
3. Check for battery voltage at the fused B(+) fuse in the relay and fuse block. If OK, go to Step 4. If not OK, repair the open fused B(+) circuit between the relay and fuse block and the battery.
4. Turn the ignition switch to the ON position. Check for battery voltage at the fused ignition switch output (run-acc) fuse in the fuse block. If OK, go to Step 5. If not OK, repair the open fused ignition switch output (run-acc) circuit between the fuse block and the ignition switch.
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. Reconnect 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 (run-acc) circuit 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 (run-acc) circuit between the relay and fuse block and the fuse block.
7. Turn the ignition switch to the OFF position. Check for battery voltage at the fused B(+) circuit 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 between the combination flasher and the fused B(+) fuse in the relay and fuse block.
8. Disconnect and isolate the battery negative cable. Check for continuity between the ground circuit 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.
9. Disconnect the instrument panel wire harness connector from the multi-function switch. Check for continuity between the hazard flasher signal circuit 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 flasher signal circuit between the relay and fuse block and the multi-function switch.
10. Check for continuity between the right turn switch sense circuit for the combination flasher in the relay and fuse block and in the instrument panel wire harness connector for the multi-function switch. Repeat this check between the left turn switch sense circuit cavities. If OK, go to Step 11 If not OK, repair the open right and/or left turn switch sense circuit(s) between the relay and fuse block and the multi-function switch.
11. Check for continuity between the right and/or left turn signal circuit (there are two of each) for the combination flasher in the relay and fuse block and the individual turn signal lamps. There should be continuity. If OK, test the multi-function switch. (Refer to ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/MULTI-FUNCTION SWITCH - DIAGNOSIS AND TESTING). If not OK, repair the open right and/or left turn signal circuit(s) between the relay and fuse block and the turn signal lamp(s).