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
2021 GMC Terrain SLT, 4WDSECTION Circuit/System Testing
NOTE:
- Use the schematics to identify the items/configurations listed below:
- Control modules the vehicle is equipped with
- The control module's B+, ignition, and ground circuits
- The control module's circuit terminals and connectors
- Some control module ground circuits may require up to 20 min after the ignition is turned Off before achieving a resistance reading of less than 5 ohms. In most cases the readings will drop below 20 ohms within 1 min indicating the control modules are going to sleep.
- Ignition/Vehicle & All vehicle systems - Off
- Disconnect the electrical connector: Appropriate control module.
- Test for less than 10 ohms between the test points: Each ground circuit terminal & Ground
- If 10 ohms or greater
- Disconnect the ground connection: Ground terminal
- Test for less than 2 ohms between the test points: Ground circuit terminal @ Control module harness & The other end of the circuit
- If 2 ohms or greater - Repair the open/high resistance in the circuit.
- If less than 2 ohms - Repair the open/high resistance in the ground connection.
- Go to next step: If less than 10 ohms
- Verify a test lamp turns On between the test points: Each B+ circuit terminal & Ground
- If the test lamp does not turn On and the circuit fuse is OK
- Remove - Test Lamp
- Test for less than 2 ohms between the test points: B+ circuit terminal @ Control module harness & Output terminal @ Fuse
- If 2 ohms or greater - Repair the open/high resistance in the circuit.
- If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
- If the test lamp does not turn On and the circuit fuse is open
- Remove - Test Lamp
- Test for infinite resistance between the test points: B+ circuit terminal @ Control module harness & Ground
- If less than infinite resistance - Repair the short to ground on the circuit.
- If infinite resistance - Replace the component: Control Module
- Go to next step: If the test lamp turns On
- Ignition - On / Vehicle - In Service Mode
- Verify a test lamp turns On between the test points: Each ignition circuit terminal & Ground
- If the test lamp does not turn On and the circuit fuse is OK
- Ignition/Vehicle - Off & Remove - Test lamp
- Test for less than 2 ohms between the test points: Ignition circuit terminal @ Control module harness & Output terminal @ Fuse
- If 2 ohms or greater - Repair the open/high resistance in the circuit.
- If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
- If the test lamp does not turn On and the circuit fuse is open
- Ignition/Vehicle - Off & Remove - Test lamp
- Test for infinite resistance between the test points: Ignition circuit terminal @ Control module harness & Ground
- If less than infinite resistance - Repair the short to ground on the circuit.
- If infinite resistance - Replace the component: Control Module
- Go to next step: If the test lamp turns On
- Replace the component: Control Module
RENDER: 1.0x
NO RELATED
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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.