Circuit/System Testing
WARNING: This page is about a different car, the 2019 Buick Cascada, 2018 Buick Cascada, and 2017 Buick Cascada. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
- Ignition OFF, and all vehicle systems OFF, it may take up to 2 min. for all vehicle systems to power down. Disconnect the harness connector at the B75C Multifunction Intake Air sensor.
- Test for less than 2 Ω between the low reference circuit terminal 7 and ground.
- If 2 Ω or greater
- Ignition OFF, disconnect the 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 or high resistance in the circuit.
- If less than 2 Ω replace the K20 Engine Control Module.
- Go to next step: If less than 2 Ω
- Ignition OFF, all vehicle systems OFF, test for less than 2 Ω between the ground circuit terminal 4 and ground.
- If 2 Ω or greater
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Test for less than 2 Ω in the ground circuit end to end.
- If 2 Ω or greater, repair the open or high resistance in the circuit.
- If less than 2 Ω, repair the open/high resistance in the ground connection.
- Go to next step: If less than 2 Ω
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 5 and ground.
- If the test lamp does not illuminate and the circuit fuse is good
- Ignition OFF, remove the test lamp and remove the fuse for the ignition voltage circuit.
- Test for less than 2 Ω in the ignition voltage circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
- Ignition OFF, remove the test lamp and remove the fuse for the ignition voltage circuit.
- Test for infinite resistance between the ignition voltage 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 greater than 2 Ω between the ignition voltage circuit terminal 5 and ground.
- If less than 2 Ω, repair the short to ground on the circuit.
- If greater than 2 Ω, test all the components connected to the circuit and repair or replace as necessary.
- Go to next step: If a test lamp illuminates
- Ignition ON, test for 4.8 - 5.2 V between the intake air temperature sensor 1 signal circuit terminal 8 and ground.
- If less than 4.8 V
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Test for infinite resistance between the signal 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 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.
- If greater than 5.2 V
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Ignition ON, test for less than 1 V between the signal 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.
NOTE:If the signal circuit is shorted to a voltage the engine control module or the sensor may be damaged.
- Go to next step: If between 4.8 - 5.2 V
- Ignition ON, verify the scan tool IAT Sensor 1 parameter is colder than -39°C (-38°F).
- If warmer than -39°C (-38°F).
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Test for infinite resistance between the signal circuit terminal 8 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 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 colder than -39°C (-38°F).
- Ignition OFF, install a 3 A fused jumper wire between the signal circuit terminal 8 and the low reference circuit terminal 7.
- Verify the scan tool IAT Sensor 1 parameter is warmer than 148°C (298°F).
- If colder than 148°C (298°F).
- Ignition OFF, remove the jumper wire, disconnect the harness connector at the K20 Engine Control Module, ignition ON.
- Test for less than 1 V between the signal circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Ignition OFF.
- 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 warmer than 148°C (298°F).
- Ignition ON, test for 4.8 - 5.2 V between the intake air temperature sensor 2 signal circuit terminal 1 and ground.
- If less than 4.8 V
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Test for infinite resistance between the signal 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 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.
- If greater than 5.2 V
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Ignition ON, test for less than 1 V between the signal 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.
NOTE:If the signal circuit is shorted to a voltage the engine control module or the sensor may be damaged.
- Go to next step: If between 4.8 - 5.2 V
- Determine if EL-38522-A
Variable Signal Generator or equivalent is available.
- EL-38522-A, Variable Signal Generator; or equivalent is not available
- Test or replace the B75C Multifunction Intake Air sensor.
- Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.
- Verify the DTC does not set.
- If the DTC sets
Replace the K20 Engine Control Module.
- Go to next step: If the DTC does not set
- If the DTC sets
- All OK.
- Go to next step: EL-38522-A, Variable Signal Generator; or equivalent is available
- Ignition OFF, connect the leads of the EL-38522-A
Variable Signal Generator as follows:
- Red lead to the signal circuit terminal 1 at the harness connector
- Black leads to ground
- Battery voltage supply lead to B+
- Set the EL-38522-A
Variable Signal Generator to the following specifications.
- Signal switch to 5 V
- Duty Cycle switch to 50 % (Normal)
- Frequency switch to 30 Hz
- Ignition ON, verify the scan tool IAT Sensor 2 parameter is between 28 - 32 Hz.
- If not between 28 - 32 Hz
Replace the K20 Engine Control Module.
- Go to next step: If between 28 - 32 Hz
- If not between 28 - 32 Hz
- Ignition OFF, and all vehicle systems OFF, it may take up to 2 min. for all vehicle systems to power down. Disconnect the harness connector at the B65 Intake Manifold and Air Temperature sensor.
- Test for less than 2 Ω between the intake air temperature sensor 3 low reference circuit terminal 3 and ground.
- If 2 Ω or greater
- Ignition OFF, disconnect the 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 or high resistance in the circuit.
- If less than 2 Ω replace the K20 Engine Control Module.
- Go to next step: If less than 2 Ω
- Ignition ON, test for 4.8 - 5.2 V between the signal circuit terminal 1 and ground.
- If less than 4.8 V
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Test for infinite resistance between the signal 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 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.
- If greater than 5.2 V
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Ignition ON, test for less than 1 V between the signal 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.
NOTE:If the signal circuit is shorted to a voltage the engine control module or the sensor may be damaged.
- Go to next step: If between 4.8 - 5.2 V
- Ignition ON, verify the scan tool IAT Sensor 3 parameter is colder than -39°C (-38°F).
- If warmer than -39°C (-38°F).
- Ignition OFF, disconnect the 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.
- Go to next step: 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 colder than -39°C (-38°F).
- Ignition OFF, install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 3.
- Verify the scan tool IAT Sensor 3 parameter is warmer than 148°C (298°F).
- If colder than 148°C (298°F).
- Ignition OFF, remove the jumper wire, disconnect the harness connector at the K20 Engine Control Module, ignition ON.
- Test for less than 1 V between the signal circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Ignition OFF.
- 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 warmer than 148°C (298°F).
- Test or replace the appropriate temperature sensor.