Coolant Temperature Sensor
- Pull off plug on coolant temperature sensor. Check resistance against ground connection. Check resistance at 2 temperature measuring points. If nominal value is not attained, replace coolant temperature sensor. If coolant temperature sensor is okay, go to step 2).
- Connect test cable (102 589 04 63 00). Set volt/ohmmeter to read mA. Pull off coupling for oxygen sensor. Switch-on ignition and read amperage. At operating temperature reading should be 7-9 Ma. At coolant temperature of approximately 60°F (20°C) reading should be 9-14 mA. Remove plug, volt/ohmmeter should read 114-132 mA. If nominal values are reached unit is okay. If nominal values are not reached, go to step 3). See Fig 1 .
- Pull off plug to controlling element. Resistance should read approx. 200 Ohms. If nominal value is not reached, replace controlling element. If controlling element is okay, go to step 4).
- Check voltage at plug connector for coolant temperature sensor. Voltage should be approximately 5 volts. If there's no voltage, repair short. If voltage is okay, go to step 5).
- Check wiring between ECU and controlling element for continuity. If continuity is okay, replace ECU. If there's no continuity, repair short in harness.