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Toyota: Fixing Prius HID Headlamp Problems

• If the reading is not equal to source voltage, isolate and repair the trouble area in the headlight assembly power supply circuit.

3. Remove the HID headlight bulb and inspect it for swelling and a white cloudy condition inside of the discharge bulb arc tube. If the bulb shows these signs of deterioration, the bulb should be replaced. Note: In the case of an aged bulb, the output and illumination may be shut off temporarily due to the “fail-safe” function of the headlight control ECU. The bulb may illuminate temporarily when switched on again.

4. If no signs of deterioration are found, swap the HID bulb between the left and right sides.

• If you move the improperly operating bulb to the opposite side and it doesn’t operate properly, replace the bulb.

• If the bulb operates properly for at least 3 minutes when swapped to the opposite side, continue to Step 5. Note: Swapping bulbs from side to side can be misleading if there is intermittent operation. A bulb that’s nearing service end-of-life may or may not work when swapped.

5. Inspect the connector at the HID ECU. Using a terminal gauge set, check the pin fit of the 12V connector at the HID ECU.

• If pin fit is loose, repair or replace the ­connector and harness.

6. Confirm proper headlight operation.

Written by the ALLDATA Community Automotive Diagnostic Team, a select group of automotive experts dedicated to helping technicians fix hard-to-repair vehicles more efficiently. © 2014 ALLDATA LLC.

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