FixVault

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the B75B MAF/IAT sensor.
  2. Ignition OFF, all vehicle systems OFF, this may take up to 2 min.
  3. CAUTION: Do NOT use a test lamp to test the continuity of the circuit. Damage to the control module may occur due to excessive current draw.
  4. Test for less than 5 Ω between the low reference circuit terminal 1 and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance, or for a short to voltage. If the circuit/connections test normal, replace the K20 ECM.
  5. Ignition ON, verify that the scan tool IAT sensor parameter is at -40°C (-40°F).
    • If warmer than the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit/connections test normal, replace the K20 ECM.
  6. NOTE: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the sensor may be damaged.
  7. Ignition ON, install a 3 A fused jumper wire between the signal circuit terminal 3 and ground. Verify the IAT sensor parameter is warmer than 134°C (274°F).
    • If colder than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the K20 ECM.
  8. If all circuits/connections test normal, test or replace the B75B MAF/IAT sensor.