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 MANUALSCHEVROLET2006CHEVY EXPRESS G2500, VAN CARGO, 6.6 2REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1534 (DATA COMMUNICATION SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC U189ACIRCUIT/SYSTEM TESTING
2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2
Circuit/System Testing
2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2SECTION Circuit/System Testing
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect harness connector X1 of the APM.
- Test for less than 0.5 volts between the wake up signal circuit terminal 3 and ground.
- If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the SDGM.
- Disconnect harness connector X1 of the PIM.
- Test for B+ between the wake up signal circuit terminal 19 and ground.
- If less than the specified value, test the circuit for an open/high resistance. If the circuit tests normal, replace the SDGM.
- Test for less than 1.0 ohm between the APM and the PIM on the following circuit terminals.
- PTLAN + APM terminal 2 and PIM terminal 25
- PTLAN - APM terminal 1 and PIM terminal 24
- If greater than the specified range, test the circuit for an open/high resistance.
- Ignition OFF, disconnect harness connector X3 of the engine control module (ECM).
- Test for less than 1.0 ohm between the APM and the ECM on the following circuit terminals.
- PTLAN + APM terminal 11 and ECM terminal 53
- PTLAN - APM terminal 10 and ECM terminal 33
- If greater than the specified range, test the circuit for an open/high resistance.
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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.