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 flowing 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; however, for diagnosis of the turn signal on warning feature, the use of a DRB III scan tool is required. Refer to the appropriate diagnostic 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 (Fuse 19 - 10 ampere) in the Junction Block (JB) and the fused B(+) fuse (Fuse 1 - 30 ampere) 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 fused B(+) fuse (Fuse 1 - 30 ampere) in the PDC. If OK, go to Step 4. If not OK, repair the open B(+) circuit between the PDC and the battery as required.
4. Turn the ignition switch to the ON position. Check for battery voltage at the fused ignition switch output (run-acc) fuse (Fuse 19 - 10 ampere) in the JB. If OK, go to Step 5. If not OK, repair the open fused ignition switch output (run-acc) circuit between the JB and 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 instrument panel wire harness connector 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 cavity in the instrument panel wire harness connector for the combination flasher. If OK, go to Step 7. If not OK, repair the open fused ignition switch output (run-acc) circuit between the combination flasher and the fused ignition switch output (run-acc) fuse (Fuse 19 - 10 ampere) in the JB as required.
7. Turn the ignition switch to the OFF position. Check for battery voltage at the fused B(+) circuit cavity of the instrument panel wire harness connector for the combination flasher. If OK, go to Step 8. If not OK, repair the open fused B(+) circuit between the combination flasher and the fused B(+) fuse (Fuse 1 - 30 ampere) in the PDC as required.
8. Disconnect the instrument panel wire harness connector for the multi-function switch from the switch connector receptacle. Check for continuity between the hazard flasher signal circuit cavities in the instrument panel wire harness connector for the combination flasher and the instrument panel wire harness connector for the multi-function switch. There should be continuity. If OK, go to Step 9. If not OK, repair the open hazard flasher signal circuit between the combination flasher and the multi-function switch as required.
9. Check for continuity between the right turn switch sense circuit cavities in the instrument panel wire harness connector for the combination flasher and the instrument panel wire harness connector for the multi-function switch. Repeat this check between the left turn switch sense circuit cavities if these same connectors. If OK, go to Step 10. If not OK, repair the open right and/or left turn switch sense circuit(s) between the combination flasher and the multi-function switch as required.
10. Check for continuity between the right and/or left turn signal circuit cavities (there are two of each) in the instrument panel wire harness connector for the combination flasher and the individual turn signal lamps. There should be continuity. If OK, test the multi-function switch. (Refer to LIGHTING - EXTERIOR/MULTI-FUNCTION SWITCH - DIAGNOSIS AND TESTING). If not OK, repair the open right and/or left turn signal circuit(s) between the combination flasher and the turn signal lamp(s) as required.