Circuit/System Testing: U02A3

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 B136 Exhaust Particulate Matter Sensor.
Test for less than 10 Ω between the ground circuit terminal 1 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.
Verify that a test lamp illuminates between the ignition circuit terminal 4 and ground.
- If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF, remove the test lamp.
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, remove the test lamp.
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 B136 Exhaust Particulate Matter Sensor.
- 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 B136 Exhaust Particulate Matter Sensor 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 B136 Exhaust Particulate Matter Sensor 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 B136 Exhaust Particulate Matter Sensor.