IAT Sensor Range & Circuit Testing: EuroVan (Engine Code AES)
NOTE:
Engine must be cold before performing test procedure.
- 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.
- 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.
- For IAT sensor location, see Fig 1 . Using a chilling agent, cool IAT sensor. Using scan tool, observe IAT sensor temperature value. Temperature value should steadily decrease. If IAT sensor temperature value did not steadily decrease, replace faulty IAT sensor. After repairs, erase DTC memory. Verify repair. Test is complete.
- Disconnect ECM harness connector. Connect Test Box (VAG 1598/18) to ECM harness connector. See CONNECTING VAG TEST BOX . Disconnect IAT sensor 2-pin connector. Using DVOM, measure resistance between IAT sensor harness connector terminal No. 1 and test box socket No. 36. See Fig 2 . Record resistance reading. Using DVOM, measure resistance between IAT sensor harness connector terminal No. 2 and test box socket No. 33. Record resistance reading. Resistance should be a maximum of 1.5 ohms for each reading. Go to next step.
- Check IAT sensor harness connector terminal No. 1 for short circuit to battery positive and ground. Check IAT sensor harness connector terminal No. 2 for short circuit to battery positive. 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. After repairs, erase DTC memory. Verify repair. Test is complete. Perform ECM relearn procedure. See TEST DRIVE RELEARN PROCEDURE .