Circuit/System Testing: U029E

Ignition OFF, all access doors closed, all vehicle systems OFF and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down. Disconnect the harness connector at the B195B Nitrogen Oxides Sensor 2.
Test for less than 10 Ω between the low reference circuit terminal 4 and ground.
- If 10 Ω or greater
1. Ignition OFF, disconnect the harness connector at the K34 Glow Plug Control Module.
2. Test for less than 2 Ω in the low reference circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, replace the K34 Glow Plug Control Module.
- If less than 10 Ω
Ignition ON.
Verify that a test lamp illuminates between the ignition circuit terminal 1 and ground.
- If the test lamp does not illuminate
1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K34 Glow Plug Control Module.
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
3. 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, replace the K34 Glow Plug Control Module.
- If the test lamp illuminates
Ignition OFF, all access doors closed, all vehicle systems OFF and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down. Disconnect the harness connectors of the device setting the DTC.
Test for less than 2 Ω in each of the Powertrain high speed GMLAN serial data circuits end to end between the B195B Nitrogen Oxides Sensor 2 harness connector and the device setting the DTC.
- If 2 Ω or greater
  Repair the open/high resistance in the serial data circuit between the B195B Nitrogen Oxides Sensor 2 and the device setting the DTC.
- If less than 2 Ω
Test for 110-130 Ω between each pair of Powertrain high speed GMLAN serial data circuits.
- If less than 110 Ω
  Refer to DTC U0074 (Chassis Expansion Bus) and DTC U0074 (Powertrain Expansion Bus) to test for a short to ground or a short between the serial data circuits.
- If greater than 130 Ω
  Refer to DTC U0074 (Chassis Expansion Bus) and DTC U0074 (Powertrain Expansion Bus) to test for an open/high resistance in the serial data circuit.
- If between 110-130 Ω
Replace the B195B Nitrogen Oxides Sensor 2.