Circuit/System Testing

NOTE: You must perform Circuit/System Verification before proceeding with Circuit/System Testing.

Check the integrity of the entire air induction system and verify that none of the following conditions exist:
- A loose or disconnected charge air cooler hose or pipe
- A blocked or obstructed charge air cooler, including: after-market grill covers
- Any snow or ice build-up at the charge air cooler in cold climates
- Any mud or dirt build-up at the charge air cooler
- A restricted or collapsed air intake duct
- An intake manifold leak
- A MAP sensor seal that is leaking, missing or damaged
- A misaligned or damaged air intake duct
- Any water intrusion in the induction system
- An Intake Manifold Resonator with a leaking seal or a cracked or broken housing
- If a condition exists
  Repair or replace component as appropriate.
- If no condition exists
Ignition OFF and all vehicle systems OFF, it may take up to 2 min. for all vehicle systems to power down. Disconnect the harness connector at the B111B Turbocharger Boost/Intake Air Temperature sensor.
Test for less than 2 Ω between the low reference circuit terminal 1 and ground.
- If 2 Ω or greater
1. Ignition OFF, disconnect the harness connector at the K20 Engine 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 or high resistance in the circuit.
  - If less than 2 Ω replace the K20 Engine Control Module.
- If less than 2 Ω
Ignition ON, test for 4.8-5.2 V between the signal circuit terminal 2 and ground.
- If less than 4.8 V
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the 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 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 K20 Engine Control Module.
- If greater than 5.2 V
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
  NOTE: If the signal circuit is shorted to a voltage the engine control module or the sensor may be damaged.
2. Ignition ON, test for less than 1 V between the signal circuit and ground.
  - If 1 V or greater, repair the short to voltage on the circuit.
  - If less than 1 V, replace the K20 Engine Control Module.
- If between 4.8-5.2 V
Ignition ON, verify the scan tool IAT Sensor 3 parameter is colder than -39°C (-38°F).
- If warmer than -39°C (-38°F).
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the signal circuit terminal 2 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 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 K20 Engine Control Module.
- If colder than -39°C (-38°F).
Ignition OFF, install a 3 A fused jumper wire between the signal circuit terminal 2 and the low reference circuit terminal 1.
Verify the scan tool IAT Sensor 3 parameter is warmer than 128°C (262°F).
- If colder than 128°C (262°F).
1. Ignition OFF, remove the jumper wire, disconnect the harness connector at the K20 ECM, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
  - If 1 V or greater, repair the short to voltage on the circuit.
  - If less than 1 V
3. Ignition OFF.
4. Test for less than 2 Ω in the 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 K20 ECM.
- If warmer than 128°C (262°F).
Test or replace the B111B Turbocharger Boost/Intake Air Temperature sensor.