Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2018 GMC Yukon XL, 2018 GMC Yukon, 2018 Chevrolet Tahoe, 2018 Chevrolet Suburban, and 2018 Cadillac Escalade ESV. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B47 Fuel Pressure Sensor. It may take up to 2 min for all vehicle systems to power down.
- Test for less than 5 Ω between the low reference circuit terminal 2 and ground.
- If 5 Ω or greater
- Ignition OFF, disconnect the X1 harness connector at the K20 Engine 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 K20 Engine Control Module.
- Go to next step : If less than 5 Ω
- Ignition ON.
- Test for 4.8 - 5.2 V between the 5 V reference circuit terminal 3 and ground.
- If less than 4.8 V
- Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module.
- 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.
- If infinite resistance
- 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 K20 Engine Control Module.
- If greater than 5.2 V
- Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module, ignition ON.
- 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 K20 Engine Control Module.
- Go to next step : If between 4.8 - 5.2 V
- Verify the scan tool Fuel Pressure Sensor parameter is less than 1 V.
- If 1 V or greater
- Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module, ignition ON.
- Test for less than 1 V between the signal circuit terminal 1 and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K20 Engine Control Module.
- Go to next step : If less than 1 V
- Install a 3 A fused jumper wire between the signal circuit terminal 1 and the 5 V reference circuit terminal 3, wait 15 s.
- Verify the scan tool Fuel Pressure Sensor parameter is 4.8 V or greater.
- If less than 4.8 V
- Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module.
- Test for infinite resistance between the signal circuit terminal 1 and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- If infinite resistance
- Test for less than 2 Ω in the signal circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K20 Engine Control Module.
- Go to next step : If 4.8 V or greater
- Test or replace the B47 Fuel Pressure Sensor.