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IAT Sensor Range & Circuit Testing: EuroVan 2.8L (Engine Code AXK)

NOTE: Engine must be cold before performing test procedure.
NOTE: On EuroVan 2.8L (engine code AXK), IAT sensor is located inside MAF sensor.
  1. Verify battery voltage is a minimum of 11.5 volts and all fuses are okay. Repair as necessary. Connect Scan Tool. See DATA LINK CONNECTOR  . Go to next step.
  2. Turn ignition on. Using scan tool, check IAT sensor temperature value. If IAT sensor temperature value deviates greatly from underhood ambient temperature, go to step  4 . If IAT sensor temperature value is approximately the same as underhood ambient temperature, go to next step.
    NOTE: Next test step tests IAT sensor through its full range.
  3. Remove intake hose from MAF/IAT sensor and Throttle Control Module. Using a chilling agent, cool IAT sensor, see Figure . Using scan tool, observe IAT sensor temperature value. Temperature value should steadily decrease. If IAT sensor temperature value did not steadily decrease, replace faulty MAF/IAT sensor. After repairs, erase DTC memory. Verify repair. Test is complete.
  4. If IAT sensor temperature value is extremely low - approximately -50°F (-46°C) - possible cause is open circuit or short to positive. Go to next step. If IAT sensor temperature value is extremely high - approximately 285°F (141°C) - possible cause is short to ground. Go to step  6 .
  5. Disconnect MAF/IAT sensor connector. Using a jumper wire, bridge IAT sensor harness connector terminals No. 1 and 3. See Figure . Using scan tool, observe IAT sensor temperature value. If IAT sensor temperature value is approximately -50°F (-46°C), turn ignition off. Go to step  7 . If IAT sensor temperature value is approximately 285°F (141°C), turn ignition off. Replace faulty MAF/IAT sensor. After repairs, erase DTC memory. Verify repair. Test is complete.
  6. Disconnect MAF/IAT sensor connector. Using scan tool, observe IAT sensor temperature value. If after disconnecting MAF/IAT sensor connector, temperature value is approximately -50°F (-46°C), turn ignition off. Replace faulty MAF/IAT sensor. After repairs, erase DTC memory. Verify repair. Test is complete. If after disconnecting MAF/IAT sensor connector, temperature value is approximately 285°F (141°C), turn ignition off. Go to next step.
  7. Disconnect ECM harness connector. Connect Test Box (VAG 1598/31) to ECM harness connector. See CONNECTING VAG TEST BOX  . Disconnect MAF/IAT sensor 5-pin connector. Using DVOM, measure resistance between IAT sensor harness connector terminal No. 1 and test box socket No. 26. See Figure . Record resistance reading. Using DVOM, measure resistance between IAT sensor harness connector terminal No. 3 and test box socket No. 27. Record resistance reading. Resistance should be a maximum of 1.5 ohms for each reading. Go to next step.
  8. Check IAT sensor harness connector terminal No. 1 for short circuit to battery positive and ground. Check IAT sensor harness connector terminal No. 3 for short circuit to battery positive and ground. Also verify IAT sensor harness connector circuits are not shorted to each other. Repair wiring harness as necessary. If wiring and IAT sensor are okay, replace faulty ECM. See ENGINE CONTROL MODULE under REMOVAL, OVERHAUL & INSTALLATION article. After repairs, erase DTC memory. Verify repair. Test is complete. Perform ECM relearn procedure. See TEST DRIVE RELEARN PROCEDURE  .
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