Circuit/System Testing

WARNING: This page is about a different car, the 2020 Buick Regal TourX, 2020 Buick Regal, 2019 Buick Regal TourX, and 2019 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.

Ignition OFF, disconnect the harness connector at the B71R Liftgate Object Sensor - Right. It may take up to 2 minutes for all vehicle systems to power down.
Test for less than 30 Ω between the low reference circuit terminal 2 and ground.
- If 30 Ω or greater
1. Ignition OFF.
2. 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.
- Go to next step: If less than 30 Ω
Disconnect the harness connector at the B71L Liftgate Object Sensor - Left.
Ignition ON, test for 4.8 - 5.2 V between the 5 V reference circuit terminal 1 and ground.
- If less than 4.8 V
1. Ignition OFF, disconnect the harness connector at the K39 Liftgate Control Module.
2. Test for infinite resistance between the 5 V reference circuit and ground
  - If less than infinite resistance, repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
3. Test for less than 2 Ω in the 5 V 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 K39 Liftgate Control Module.
- If greater than 5.2 V
1. Ignition OFF, disconnect the harness connector at the K39 Liftgate Control Module, Ignition ON.
2. Test for less than 1 V between the 5 V reference circuit and ground.
  - If 1 V or greater, repair the short to voltage on the circuit.
  - If less than 1 V, replace the K39 Liftgate Control Module.
- Go to next step: If between 4.8 - 5.2 V
Test or replace the B71 Liftgate Object Sensors.