Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 411 (MIRROR SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESPOWER MIRRORS INOPERATIVECIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G3500, Van Passenger Extended
Circuit/System Testing
2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2009 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
Mirror Motor Circuit Test
- Ignition OFF, disconnect the X4 harness connector at the appropriate door module.
- Ignition ON, verify a test lamp does not illuminate between the following control circuit terminals and ground:
- Control circuit terminal 1
- Control circuit terminal 2
- Control circuit terminal 5
- If the test lamp illuminates, test the appropriate control circuit for a short to voltage.
- Ignition OFF, test for infinite resistance between the following control circuits and ground:
- Control circuit terminal 1
- Control circuit terminal 2
- Control circuit terminal 5
- Test for 20-120 ohms between the control circuit terminal 1 and the control circuit terminal 2.
- If not within the specified range, test both control circuits for an open/high resistance. If the circuits test normal, test or replace the rearview mirror.
- Test for 20-120 ohms between the control circuit terminal 5 and the control circuit terminal 2.
- If not within the specified range, test both control circuits for an open/high resistance. If the circuits test normal, test or replace the rearview mirror.
- If all circuits test normal, replace the appropriate door module.
Mirror Position Sensor Circuit Test
- Ignition OFF, disconnect the X3 harness connector at the appropriate door module.
- Ignition ON, verify a test lamp does not illuminate between the following circuit terminals and ground:
- 5-volt reference circuit terminal 7
- Signal circuit terminal 2
- Signal circuit terminal 3
- Low reference circuit terminal 6
- If the test lamp illuminates, test the appropriate circuit for a short to voltage.
- Ignition OFF, test for infinite resistance between the following circuits and ground:
- 5-volt reference circuit terminal 7
- Signal circuit terminal 2
- Signal circuit terminal 3
- Low reference circuit terminal 6
- If less than the specified value, test the appropriate circuit for a short to ground.
- Test for 4K-7K ohms between the 5-volt reference circuit terminal 7 and the low reference circuit terminal 6.
- If not within the specified range, test the 5-volt reference circuit and the low reference circuit for an open/high resistance. If the circuits test normal, test or replace the rearview mirror.
- Test for 1K-7K ohms between the 5-volt reference circuit terminal 7 and the signal circuit terminal 2.
- If not within the specified range, test the signal circuit for an open/high resistance. If the circuits test normal, test or replace the rearview mirror.
- Test for 1K-7K ohms between the 5-volt reference circuit terminal 7 and the signal circuit terminal 3.
- If not within the specified range, test the signal circuit for an open/high resistance. If the circuits test normal, test or replace the rearview mirror.
- If all circuits test normal, replace the door module.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.