Right Turn Signal Circuit Malfunction
What does B1004 mean?
The B1004 code means the vehicle's onboard diagnostic system has detected: Right Turn Signal Circuit Malfunction. This is a moderate severity code.
Common Symptoms
- Right turn signal not flashing
- Fast clicking from turn signal relay
- Right turn indicator on dash stays solid
- Intermittent right turn signal operation
- Right side hazard lights not working
Probable Causes (Ranked by Likelihood)
- Burned out right turn signal bulb Very High
- Corroded bulb socket High
- Faulty flasher relay or module Moderate
- Broken wiring to right turn signal light Moderate
- Turn signal switch malfunction Low
Step-by-Step Diagnostic Procedure
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Inspect all right turn signal bulbs front and rear
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Check bulb sockets for corrosion or damage
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Test ground connections at light housings
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Verify flasher relay function
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Test turn signal switch inputs with scan tool
Frequently Asked Questions
I replaced the bulb but the signal still does not work. What next?
Check the bulb socket for corrosion and verify the ground connection. If those are fine, test the flasher relay and wiring with a multimeter.
Can LED replacement bulbs cause this code?
Yes. LED bulbs draw less current than standard bulbs, which can cause hyperflash or trigger fault codes. You may need a load resistor or LED-compatible flasher relay.
Where is the turn signal flasher relay?
The flasher relay location varies by vehicle. It is commonly found in the fuse box under the dashboard or in the engine bay fuse box. Check your owner's manual for the exact location.