Circuit/System Testing
NOTE:
You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
- Inspect for the following conditions:
- A loose or disconnected CAC hose or pipe
- A blocked or obstructed CAC, including: after market grill covers
- Any snow or ice build-up at the CAC in cold climates
- Any mud or dirt build-up at the CAC
- A restricted or collapsed air intake duct
- An intake manifold leak
- A MAP sensor seal that is leaking, missing, or damaged
- If you find any of the above conditions, repair as necessary.
- Engine idling at operating temperature. Observe the Airflow Leak Equivalence Ratio parameter while slowly increasing the engine speed until reaching wide open throttle (WOT). After 10 s, the value should stabilize and be between 0.8:1 and 1.2:1.
- If not within the specified range, test the charge air cooler system and air inlet system for leaks. Perform the Full System Air Leak Test and the Induction System Smoke Test. Refer to Charge Air Cooler Diagnosis (Full System Air Leak Test) , Charge Air Cooler Diagnosis (Induction System Smoke Test) . If no air leaks are found, test all of the temperature sensors' circuits in the Circuit/System Verification for high resistance.
- Ignition OFF, disconnect the harness connector at the appropriate temperature sensor as determined in the Circuit/System Verification.
- Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 Ω between the appropriate low reference circuit terminal 2 or B and ground.
- If greater than the specified range, test the appropriate low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
- Ignition ON, verify the scan tool parameter of the appropriate temperature sensor is colder than -39°C (-38°F).
- If warmer than the specified range, test the appropriate signal circuit terminal 1 or A for a short to ground. If the circuit tests normal, replace the K20 ECM.
- Install a 3A fused jumper wire between the appropriate signal circuit terminal 1 or A and ground. Verify the appropriate scan tool parameter is warmer than
- 197°C (387°F); Charge Air Cooler Temperature
- 213°C (415°F); IAT Sensor 1
- 213°C (415°F); IAT Sensor 2
- If colder than the specified range, test the appropriate signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
- If all circuits test normal, test or replace the appropriate temperature sensor.
NOTE:
If a short to voltage is found on the sensor signal circuit, the 3A fuse in the jumper wire will open.