Circuit/System Testing
WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition/Vehicle & All vehicle systems - Off
- Disconnect the appropriate electrical connector: T8 Ignition Coil
- Test for less than 10 ohms between the test points: Ground circuit terminal 1/A & 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 1/A @ Component harness & The other end of the circuit @ Ground terminal
- 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
- Ignition - On / Vehicle - In Service Mode
- Verify a test lamp does not turn On between the test points: Control circuit terminal 3/C & B+
- If the test lamp turns On
- Ignition/Vehicle - Off & Remove - Test lamp
- Disconnect the electrical connector: K20 Engine Control Module
- Test for infinite resistance between the test points: Control circuit terminal 3/C @ Component harness & Ground
- If less than infinite resistance - Repair the short to ground on the circuit.
- If infinite resistance - Replace the component: K20 Engine Control Module
- Go to next step: If the test lamp does not turn On
- Remove - Test Lamp
- Engine - Running
- Verify the scan tool parameter: Ignition Coil 1 - 6 Control Circuit High Voltage Test Status = OK or Not Run
- If not the specified state
- Ignition/Vehicle - Off
- Disconnect the electrical connector: K20 Engine Control Module
- Test for less than 1 V between the test points: Control circuit terminal 3/C @ Component harness & Ground
- If 1 V or greater - Repair the short to voltage on the circuit.
- If less than 1 V - Replace the component: K20 Engine Control Module
- Go to next step: If the specified state
- Ignition/Vehicle - Off
- Connect a 3 A fused jumper wire between the test points: Control circuit terminal 3/C & Ignition circuit terminal 4/D
- Engine - Running
- Verify the scan tool parameter: Ignition Coil 1 - 6 Control Circuit High Voltage Test Status = OK or Not Run
- If not the specified state
- Ignition/Vehicle - Off & Remove - Jumper wire(s)
- Disconnect the electrical connector: K20 Engine Control Module
- Test for less than 2 ohms between the test points: Control circuit terminal 3/C @ Component harness & The other end of the circuit @ Control module harness
- If 2 ohms or greater - Repair the open/high resistance in the circuit.
- If less than 2 ohms - Replace the component: K20 Engine Control Module
- Go to next step: If the specified state
- Test or replace the component: T8 Ignition Coil
NOTE:
It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.