Component Testing

WARNING: This page is about a different car, the 2018 Chevrolet Suburban 3500 HD. However, it is still accessible from the selected car via links, so may be relevant.

Perform the Circuit/System Testing first.
Ignition Off.
Connect the X175 harness connector.
Remove the fluid pan from the T12 Automatic Transmission Assembly.
Disconnect the harness connector at the B15 Transmission Internal Mode Switch, ignition On.
Test for 8.3 - 9.4 V between the 9 V reference 1 circuit terminal 10 and ground.
- If less than 8.3 V
1. Ignition Off.
2. Disconnect the X176 connector, ignition On.
3. Test for 8.3 - 9.4 V between terminal 19 and ground.
  - If less than 8.3 V
    Replace the automatic transmission wiring harness, electrical connector passage sleeve.
  - If between 8.3 - 9.4 V
    Replace the transmission control wiring harness.
- If greater than 9.3 V
1. Ignition Off.
2. Disconnect the X176 connector, ignition On.
3. Test for 8.3 - 9.4 V between terminal 19 and ground.
  - If greater than 9.4 V
    Replace the automatic transmission wiring harness, electrical connector passage sleeve.
  - If between 8.3 - 9.4 V
    Replace the transmission control wiring harness.
- Go to next step: If between 8.3 - 9.4 V
Connect a 3 A fused jumper wire between the 9 V reference 1 circuit terminal 10 and the signal S circuit terminal 7.
Verify the scan tool signal S circuit parameter displays 4.8 - 5.2 V.
- If less than 4.8 V
1. Ignition Off.
2. Disconnect the X176 connector.
3. Connect a 3 A fused jumper wire between the 9 V reference 1 circuit terminal 19 and the signal S circuit terminal 6, ignition On.
4. Verify the scan tool signal S parameter displays 4.8 - 5.2 V.
  - If less than 4.8 V
    Replace the automatic transmission wiring harness, electrical connector passage sleeve.
  - If between 4.8 - 5.2 V
    Replace the transmission control wiring harness.
- If greater than 5.2 V
1. Ignition Off.
2. Disconnect the X176 connector.
3. Connect a 3 A fused jumper wire between the 9 V reference 1 circuit terminal 19 and the signal S circuit terminal 6, ignition On.
4. Verify the scan tool signal S parameter displays 4.8 - 5.2 V.
  - If greater than 5.2 V
    Replace the automatic transmission wiring harness, electrical connector passage sleeve.
  - If between 4.8 - 5.2 V
    Replace the transmission control wiring harness.
- Go to next step: If between 4.8 - 5.2 V
Replace the B15 Transmission Internal Mode Switch.