Reverse Output Circuit
Code P0813 indicates a problem with the reverse output circuit, which controls the reverse lamps and related systems. The PCM has detected an electrical fault in the circuit responsible for activating reverse lights when the transmission is in reverse gear.
What You Might Notice
- Reverse lamps do not illuminate when in reverse
- Reverse lamps stay on continuously even when not in reverse
- No reverse lamp operation at all
- Potential transmission shift issues
- Check engine light illuminated
Most Common Causes
- 1
Defective Reverse Position Sensor
The reverse gear position sensor fails to detect when the transmission is in reverse, preventing the reverse lamps from activating properly.
- 2
Bad Neutral Safety Switch
The neutral safety switch malfunctions, disrupting the signal needed to activate reverse lamps and potentially affecting transmission operation.
- 3
Shorted Wiring in Reverse Circuit
Damaged, corroded, or shorted wiring harnesses in the reverse output circuit cause intermittent or continuous lamp operation.
- 4
Faulty PCM or Programming Error
The powertrain control module fails to properly process reverse position signals or contains corrupted programming affecting reverse circuit control.
How to Diagnose It
- 1
Check Defective Reverse Position Sensor — The reverse gear position sensor fails to detect when the transmission is in reverse, preventing the reverse lamps from activating properly.
- 2
Check Bad Neutral Safety Switch — The neutral safety switch malfunctions, disrupting the signal needed to activate reverse lamps and potentially affecting transmission operation.
- 3
Check Shorted Wiring in Reverse Circuit — Damaged, corroded, or shorted wiring harnesses in the reverse output circuit cause intermittent or continuous lamp operation.
- 4
Check Faulty PCM or Programming Error — The powertrain control module fails to properly process reverse position signals or contains corrupted programming affecting reverse circuit control.
How to Fix It
- 1
Test and Replace Reverse Position Sensor
Use a DVOM to test the reverse position sensor for proper voltage and continuity. If faulty, replace the sensor with an OEM or quality aftermarket unit.
- 2
Inspect and Repair Wiring Harness
Inspect all wiring and connectors in the reverse output circuit for corrosion, damage, or loose connections. Repair or replace damaged wiring as needed.
- 3
Test and Replace Neutral Safety Switch
Test the neutral safety switch for proper operation using a diagnostic scanner. Replace if it fails continuity or voltage tests.
- 4
PCM Reprogramming or Replacement
If all sensors and circuits test good, the PCM may require reprogramming through the vehicle manufacturer or replacement if programming cannot resolve the fault.
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