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 MANUALSCHEVROLET2012CHEVY EXPRESS G2500, VAN PASSENGER, 4.8L ENG VIN AREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 820 (WIRING SYSTEMS AND POWER MANAGEMENT - DTC B1370 TO DTC B1475)DTC B1370CIRCUIT/SYSTEM TESTING
2012 Chevrolet Chevy Express G2500, Van Passenger, 4.8L Eng VIN A
Circuit/System Testing
2012 Chevrolet Chevy Express G2500, Van Passenger, 4.8L Eng VIN ASECTION Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Chevrolet Tahoe, 2007 Chevrolet Suburban, and 2007 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
- Inspect the Ign Switch fuse for open. The fuse should be OK.
- If the fuse is open, test the following circuits for a short to ground, if all circuits test OK, replace the BCM.
- Battery positive voltage of the ignition switch
- Accessory voltage
- Off/Run crank voltage
- Ignition 1 voltage
- If the fuse is open, test the following circuits for a short to ground, if all circuits test OK, replace the BCM.
- Disconnect the ignition switch connector.
- Test for battery positive voltage between the battery positive voltage circuit of the ignition switch and ground.
- If less than battery positive voltage, repair the circuit for an open/high resistance
- Perform the ignition switch component test.
- If the ignition switch fails, replace the ignition switch.
- Ignition OFF, disconnect BCM connector C1, test for less than 1.0 volt between the following circuits of the BCM and ground.
- Ignition key out, test for less than 1.0 volt between the following circuits of the BCM and ground.
- Ignition key resistor signal
- Off/Run crank
- Accessory voltage
- Ignition 1 voltage
- If more than 1.0 volt, repair the circuit for a short to voltage.
- Test for less than 1.0 ohm of resistance between the BCM and the ignition switch on the following circuits.
- Ignition key resistor signal
- Off/Run crank
- Accessory voltage
- Ignition 1 voltage
- If greater than 5 ohms, repair the circuit for open/high resistance
- Test for infinite resistance between the ignition key resistor signal circuit of the BCM and ground.
- If less than infinite resistance, repair the signal circuit for a short to ground.
- Replace the BCM.
IMPORTANT:
The ignition switch component test must be preformed before proceeding with this test to verify the integrity of the switch.
RENDER: 1.0x
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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.