Circuit/System Testing

NOTE:

Use the schematics and connector end views to identify the K71 Transmission Control Module (or Q8 Control Solenoid Valve Assembly) ground, B+, ignition, serial data wake-up signal, and high speed GMLAN serial data circuit terminals.

Ignition OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 meters (9.8 feet) away from vehicle. Disconnect the X1 harness connector at the K71 Transmission Control Module. It may take up to 2 minutes for all vehicle systems to power down.
Test for less than 10 Ω between each ground circuit terminal and ground.
- If 10 Ω or greater
1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, repair the open/high resistance in the ground connection.
- If less than 10 Ω
Ignition ON.
If equipped, verify a test lamp illuminates between each B+ circuit terminal and ground.
- If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 Ω in the B+ 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
1. Ignition OFF.
2. Test for infinite resistance between the B+ circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance, replace the K71 Transmission Control Module.
- If the test lamp illuminates
Ignition ON.
If equipped, verify a test lamp illuminates between each ignition circuit terminal and ground.
- If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 Ω in the ignition 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 OK and there is voltage at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the ignition circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance, replace the K71 Transmission Control Module.
- If the test lamp illuminates
Ignition ON.
If equipped, verify a test lamp illuminates between the serial data wake-up signal circuit and ground.
- If the test lamp does not illuminate
1. Ignition OFF, disconnect the harness connectors at the K9 Body Control Module.
2. Test for infinite resistance between the serial data wake-up signal circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance
3. Test for less than 2 Ω in the serial data wake-up 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 K9 Body Control Module.
- If the test lamp illuminates
Ignition OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 meters (9.8 feet) away from vehicle. It may take up to 2 minutes for all vehicle systems to power down.
Test for 110-130 Ω between each pair of high speed GMLAN serial data circuits.
- If less than 110 Ω
  Refer to Scan Tool Does Not Communicate with High Speed GMLAN Device to test for a short to ground or a short between the serial data circuits.
- If greater than 130 Ω
  Refer to Scan Tool Does Not Communicate with High Speed GMLAN Device to test for an open/high resistance in the serial data circuit.
- If between 110-130 Ω
Replace the K71 Transmission Control Module.