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.
Circuit/System Testing
2018 Buick Regal BaseSECTION Circuit/System Testing
- Ignition OFF and all vehicle systems OFF, scan tool disconnected, disconnect the harness connector at the K77 Remote Control Door Lock Receiver. It may take up to 2 min for all vehicle systems to power down.
- Test for less than 30 Ω between the low reference circuit terminal 1 and ground.
- If 30 Ω or greater
- Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
- Test for less than 2 Ω in the low reference circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K9 Body Control Module.
- Go to next step: If less than 30 Ω
- Ignition ON.
- Test for greater than 11.5 V between the B+ circuit terminal 4 and ground.
- If 11.5 V or less
- Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
- Test for infinite resistance between the B+ circuit and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- Go to next step: If Infinite resistance.
- Test for less than 2 Ω in the B+ circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K9 Body Control Module.
- Go to next step: If greater than 11.5 V
- Test for 0.001 - 6 V between the serial data circuit terminal 2 and ground.
- If less than 0.001 V
- Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
- Test for infinite resistance between the serial data circuit and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the serial data circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K9 Body Control Module.
- If greater than 6 V
- Ignition OFF, disconnect the harness connector at the K9 Body Control Module, ignition ON.
- Test for less than 0.001 V between the serial data circuit and ground.
- If 0.001 V or greater, repair the short to voltage on the circuit.
- If less than 0.001 V, replace the K9 Body Control Module.
- Go to next step: If between 0.001 - 6 V
- Ignition OFF, disconnect the X1 and X2 harness connectors at the K9 Body Control Module, ignition ON.
- Test for less than 0.001 V between the K9 Body Control Module serial data circuit terminal 26 X1 and ground.
- If 0.001 V or greater
Repair the short to voltage on the circuit.
- Go to next step: If less than 0.001 V
- If 0.001 V or greater
- Ignition OFF.
- Test for infinite resistance between the K9 Body Control Module serial data circuit terminal 26 X1 and ground.
- If less than infinite resistance
Repair the short to ground on the circuit.
- Go to next step: If infinite resistance
- If less than infinite resistance
- Test for less than 2 Ω between the K9 Body Control Module serial data circuit terminal 26 X1 and the K77 Remote Control Door Lock Receiver serial data circuit terminal 3.
- If 2 Ω or greater
Repair the open/high resistance in the circuit.
- Go to next step: If less than 2 Ω
- If 2 Ω or greater
- Replace the K77 Remote Control Door Lock Receiver.
- Verify the keyless entry functions operate.
- If the keyless entry functions do not operate
Replace the K9 Body Control Module
- Go to next step: If the keyless entry functions operate
- If the keyless entry functions do not operate
- All OK.
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.