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 MANUALSCHEVROLET2008HHR LT, 2.4 P, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 49 (DATA COMMUNICATION SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESSCAN TOOL DOES NOT COMMUNICATE WITH HIGH SPEED GMLAN DEVICECIRCUIT/SYSTEM TESTING
2008 Chevrolet HHR LT, 2.4 P, Automatic
Circuit/System Testing
2008 Chevrolet HHR LT, 2.4 P, AutomaticSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 Pontiac G5 and 2008 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
- Test for less than 1.0 ohm between the ground circuit terminal 5 of the DLC and ground.
- If greater than the specified range, test the ground circuit for open/high resistance.
- Ignition OFF, disconnect the X2 harness connector at the BCM.
- Test for less than 2 ohms on the serial data circuit between terminal 6 of the DLC and terminal 1 of the BCM.
- If greater than the specified range, test the serial data circuit for open/high resistance.
- Ignition OFF, disconnect the X4 harness connector at the BCM.
- Test for less than 1 ohm between ground circuit terminal E12 and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Ignition OFF, disconnect the X3 harness connector at the BCM.
- Ignition ON, verify a test lamp illuminates between each B+ circuit terminal D12 of the BCM and ground.
- If the test lamp does not illuminate, test the B+ circuit for an open/high resistance or short to ground.
- Ignition ON, test for less than 1 volt between the serial data circuit terminal 6 of the DLC and ground, and terminal 14 of the DLC and ground.
- If greater than the specified range, test the serial data circuit for a short to voltage.
- Test for infinite resistance between the serial data circuit terminal 6 of the DLC and ground, and terminal 14 of the DLC and ground.
- If less than the specified value, test the serial data circuit for a short to ground.
- Disconnect the X2 harness connector at the electronic power steering control module (EPS).
- Test for infinite resistance between the serial data circuits terminal 6 and terminal 14 of the DLC.
- If less than the specified value, test the serial data circuits for a short between them.
- Connect the X2 X3 and X4 harness connectors at the BCM and the X2 harness connector at the EPS.
- Disconnect the appropriate harness connector at the ECM.
- RPO L61/LE5 - X1
- RPO LNF - X2
- Attempt to communicate with the vehicle control interface module (VCIM). Communication should not be available.
- If communication is available, replace the ECM.
- Ignition OFF, disconnect the harness connector at the TCM.
- Attempt to communicate with the VCIM. Communication should not be available.
- If communication is available, test the following serial data circuits for a short between the circuits, short to voltage, or a short to ground between the TCM and the ECM. If the circuits test normal, replace the TCM.
- RPO L61/LE5 - terminal 43
- RPO L61/LE5 - terminal 44
- RPO L61/LE5 - terminals 43 and 44
- RPO LNF -terminal 33
- RPO LNF - terminal 53
- RPO LNF - terminals 33 and 53
- If communication is available, test the following serial data circuits for a short between the circuits, short to voltage, or a short to ground between the TCM and the ECM. If the circuits test normal, replace the TCM.
- Ignition OFF, disconnect the harness connector atthe EBCM.
- Attempt to communicate with the VCIM. Communication should not be available.
- If communication is available, test the following serial data circuits for a short between the circuits, short to voltage, or a short to ground between the EBCM and the TCM. If the circuits test normal, replace the EBCM.
- RPO JM4 - terminal 21
- RPO JM4 - terminal 23
- RPO JM4 - terminals 21 and 23
- RPO JL4 - terminal 14
- RPO JL4 - terminal 11
- RPO JL4 - terminals 14 and 11
- If communication is available, test the following serial data circuits for a short between the circuits, short to voltage, or a short to ground between the EBCM and the TCM. If the circuits test normal, replace the EBCM.
- Ignition OFF, disconnect the X3 harness connector at the VCIM.
- Attempt to communicate with the EPS. Communication should not be available.
- If communication is available, test the following serial data circuits for a short between the circuits, short to voltage, or a short to ground between the VCIM and the TCM. If the circuits test normal, replace the VCIM.
- terminal 9
- terminal 8
- If communication is available, test the following serial data circuits for a short between the circuits, short to voltage, or a short to ground between the VCIM and the TCM. If the circuits test normal, replace the VCIM.
- Ignition OFF, disconnect the X2 harness connector at the BCM. Attempt to communicate with the EPS. Communication should not be available.
- If communication is available, test the following serial data circuits for a short between the circuits, short to voltage, or a short to ground between the BCM and the VCIM. If the circuits test normal, replace the BCM.
- terminal 2
- terminal 20
- If communication is available, test the following serial data circuits for a short between the circuits, short to voltage, or a short to ground between the BCM and the VCIM. If the circuits test normal, replace the BCM.
- Ignition OFF, disconnect the X2 harness connector at the EPS.
- Ignition ON, test for less than 1 volt between the following serial data circuits of EPS and ground.
- terminal 4
- terminal 5
- If greater than the specified range, test the circuit for a short to voltage.
- Test for infinite resistance between the following serial data circuits of EPS and ground.
- terminal 4
- terminal 5
- If less than the specified value, test the circuit for a short to ground.
- Test for infinite resistance between the serial data circuits terminal 4 terminal 5 of the EPS.
- If less than the specified Value, test the serial data circuits for a short between them.
- If the circuits test normal, replace the EPS.
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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.