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 concern on the vehicle being diagnosed, test the charging system as required.

WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, 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 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 ignition run fuse and the flasher fuse in the Junction Block (JB). 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 flasher fuse in the JB. If OK, go to Step 4. If not OK, repair the open fused B(+) circuit between the JB and the Power Distribution Center (PDC).
4. Turn the ignition switch to the ON position. Check for battery voltage at the ignition run fuse in the JB. If OK, go to Step 5. If not OK, repair the open fused ignition switch output (RUN) circuit between the JB 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 JB 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) circuit cavity in the JB for the combination flasher. If OK, go to Step 7. If not OK, repair the open fused ignition switch output (RUN) circuit between the combination flasher and the ignition run fuse in the JB.
7. Turn the ignition switch to the OFF position. Check for battery voltage at the B(+) circuit of the JB for the combination flasher. If OK, go to Step 8. If not OK, repair the open B(+) circuit between the combination flasher and the flasher fuse in the JB.
8. Disconnect and isolate the battery negative cable. Disconnect the instrument panel wire harness connector for the turn signal and hazard warning switches from the multi-function switch connector. Check for continuity between the ground circuit of the instrument panel wire harness connector for the left multi-function switch and a good ground. There should be continuity. If OK, go to Step 9. If not OK, repair the open ground circuit.
9. Check for continuity between the hazard switch sense circuit of the instrument panel wire harness connector for the multi-function switch and a good ground. There should be no continuity. If OK, go to Step 10. If not OK, repair the shorted hazard switch sense circuit between the multi-function switch and the combination flasher.
10. Check for continuity between the hazard switch sense circuit of the JB 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 11. If not OK, repair the open hazard switch sense circuit between the multi-function switch and the combination flasher.
11. Check for continuity between the turn switch sense circuit of the instrument panel wire harness connector for the multi-function switch and a good ground. There should be no continuity. If OK, go to Step 12. If not OK, repair the shorted left turn switch sense circuit between the multi-function switch and the combination flasher.
12. Check for continuity between the left turn switch sense circuit of the JB 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 13. If not OK, repair the open left turn switch sense circuit between the multi-function switch and the combination flasher.
13. Check for continuity between the right turn switch sense circuit of the instrument panel wire harness connector for the left multi-function switch and a good ground. There should be no continuity. If OK, go to Step 14. If not OK, repair the shorted right turn switch sense circuit between the left multi-function switch and the combination flasher.
14. Check for continuity between the right turn switch sense circuit of the JB for the combination flasher and the instrument panel wire harness connector for the multi-function switch. There should be continuity. If OK, test the left multi-function switch. (Refer to ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/LEFT MULTI-FUNCTION SWITCH - DIAGNOSIS AND TESTING). If not OK, repair the open right turn switch sense circuit between the multi-function switch and the combination flasher as required.