Test Chart 1
Engine Coolant Temperature (ECT) Sensor -G62-, Checking
Recommended special tools and equipment
- VAG1526A multimeter
- VAG1594A connector test kit
- VAG1598/31 test box
Test requirements:
- Fuses for engine electronics OK
- Engine cold
Checking function
- Connect diagnostic tester. VAS 5051, Connecting and Select Functions
- Switch ignition on.
- In diagnostic function "33 - OBD", select "Mode 1: Checking measured values."
- Select desired measuring value "PID 05: Coolant temperature".
- Specified value: approx. ambient temperature
NOTE: If a temperature is indicated which differs greatly from ambient temperature of sensor, check sensor and sensor wires for contact resistances and open circuit.
- Start engine and let run at idle.
- Specified value: Temperature value must rise evenly
NOTE:
- The temperature increases in increments of 1.0 degrees C.
- If the engine shows problems in certain temperature ranges and if the temperature does not climb uniformly, the temperature signal is intermittent and the sensor should be replaced.
- End diagnosis and switch ignition off.
If indications do not resemble description:
Checking internal resistance
- Disconnect harness connector -2- at Engine Coolant Temperature (ECT) Sensor -G2-/- G62-.
- Connect multimeter between terminal C and D of sensor for resistance measurement.
Range A displays resistance values for the temperature range of 0 to 50 degrees C, range B displays resistance values for the temperature range of 50 to 100 degrees C.
Read-out examples:
- 30 degrees C corresponds to a resistance of 1500 to 2000 Ohms
- 80 degrees C corresponds to a resistance of 275 to 375 Ohms
If specified value is not obtained:
- Replace Engine Coolant Temperature (ECT) Sensor -G62-.
If specified value is obtained:
Checking wire connections
- Connect test box to wiring harness of Engine Control Module (ECM); ECM is not connected.
- Check the following wire connections for open circuit according to wiring diagram:
Harness connector Terminal Test box Socket
3 108
4 (signal) 93
- Specified value: Wire resistance max 1.5 Ohms
- Check wires for short circuit to each other as well as to B+ and Ground (GND).
- Specified value: infinity ohm (no continuity)
- If necessary, repair wire connection.
If no malfunctions are found in wires:
- Replace Engine Control Module (ECM).
Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1. Check DTC memory. Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase DTC memory. Diagnostic Mode 04 - Erase DTC Memory
3. If DTC memory was erased, generate readiness code.
- End diagnosis and switch ignition off.