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Home >> Volkswagen >> 2005 >> New Beetle Convertible (1Y1) L4-2.0L (BEV) >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Sensors and Switches - Computers and Control Systems >> Coolant Temperature Sensor/Switch (For Computer) >> Testing and Inspection

Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection



Engine Coolant Temperature (ECT) Sensor, Checking

NOTE: Use only gold-plated terminals when servicing terminals in harness connector of sensor.

Recommended special tools and equipment
- VA.G 1526 multimeter or V.A.G 1715 multimeter
- V.A.G 1594 connector test kit
- Wiring diagram

Requirements







- The respective fuses of Motronic Engine Control Module (ECM) -J220- must be OK.
- Parking brake must be engaged or else daylight driving lights will be switched on.
- For vehicles with automatic transmission, selector lever must be in position -P- or -N-
- Engine must be cold.

Function test (vehicles with engine code AEG)
- Connect diagnostic tester. Diagnostic Tester, Connecting
- Switch ignition on.
- Under address word 33, select "Diagnostic mode 1: Check measured values."
- Select measuring value "PID 05: Coolant temperature".
- Check specified value of coolant temperature:







If specified value is not obtained:
- Continue test according to the following table:







1) If a temperature is indicated which differs greatly from ambient temperature of sensor, check sensor wires for contact resistance.

If specified value is obtained:
- Start engine and let run at idle.

The temperature must climb uniformly

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.

Continuation of test if indication is approx. -46.5 degrees C







- Disconnect 4-pin connector from Engine Coolant Temperature (ECT) sensor -G62- with Engine Coolant Temperature (ECT) sensor -G2- (arrow).

Vehicles with old connector shape







- Bridge terminals 1 + 3 of connector using respective adapter cables and observe indication on display.

Vehicles with new connector shape







- Bridge connector terminals 3 + 4 using respective adapter cables and observe the indication on display.

Continuation for all connector shapes
If indication jumps to approx. 141.0 degrees C:
- End diagnosis and switch ignition off.
- Replace Engine Coolant Temperature (ECT) sensor -G62- with Engine Coolant Temperature (ECT) sensor -G2-.

WARNING:
- The cooling system is under pressure.
- Danger of scalding when opening.

- Erase DTC memory of Engine Control Module (ECM). Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If indication remains at approx. -46.5 degrees C:
- End diagnosis and switch ignition off.
- Check wires according to wiring diagram.

Continuation of test if indication is approx. 141.0 degrees C







- Disconnect 4-pin connector from Engine Coolant Temperature (ECT) sensor -G62- with Engine Coolant Temperature (ECT) sensor -G2- (arrow).

If indication jumps to approx. -46.5 degrees C:
- End diagnosis and switch ignition off.
- Replace Engine Coolant Temperature (ECT) sensor -G62- with Engine Coolant Temperature (ECT) sensor -G2-.

WARNING:
- The cooling system is under pressure.
- Danger of scalding when opening.

- Erase DTC memory of Engine Control Module (ECM). Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If indication remains at approx. 141.0 degrees C:
- End diagnosis and switch ignition off.
- Check wires according to wiring diagram.

Checking wiring
- Connect test box to control module wiring harness. connect test box for wiring test. Test Box, Connecting For Wiring Test

Vehicles with old connector shape







- Check wires between test box and 4-pin connector for open circuit according to wiring diagram.

Terminal 1 + socket 67
Terminal 3 + socket 53

Wire resistance: max. 1.5 Ohms

Vehicles with new connector shape







- Check wires between test box and 4-pin connector for open circuit according to wiring diagram.

Terminal 3 + socket 93
Terminal 4 + socket 108

Wire resistance: max. 1.5 Ohms

Continued for all connector shapes
- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+.

Specified value: Infinite Ohms

If no malfunctions are found in wires.

Vehicles with old connector shape







- Perform a resistance measurement at Engine Coolant Temperature (ECT) sensor -G62- terminal 1 (Ground) and 3 (signal).

Vehicles with new connector shape







- Measure resistance at Engine Coolant Temperature (ECT) sensor -G62-, terminals C (signal) and D (Ground).

Continued for all connector shapes







Range A displays resistance values for temperature range of 0 to 50 degrees C, range B displays resistance values for temperature range of 50 to 100 degrees C.

Read-out examples:
- 30 degrees C is in range A and corresponds to a resistance of 1.5 to 2.0 k Ohms
- 80 degrees C is in range B and corresponds to a resistance of 275 to 375 Ohms

If specified value is not obtained:
- Replace Engine Coolant Temperature (ECT) sensor -G62- with Engine Coolant Temperature (ECT) sensor -G2-.

WARNING:
- The cooling system is under pressure.
- Danger of scalding when opening.

- Erase DTC memory of Engine Control Module (ECM). Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If no malfunctions are detected in the wires and the resistance values are OK:
- Replace Motronic Engine Control Module (ECM) -J220-.

Function test (Vehicles with engine code AVH, AZG, BDC, BEV, BCD)
- Connect diagnostic tester. Diagnostic Tester, Connecting
- Switch ignition on.
- Under address word 33, select "Diagnostic mode 1: Check measured values."
- Select measuring value "PID 05: Coolant temperature".
- Check specified value of coolant temperature:







If specified value is not obtained:
- Continue test according to the following table:







If specified value is obtained:
- Start engine and let run at idle.

The temperature must climb uniformly

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.

Continuation of test if indication is approx. -40.0 degrees C:







- Disconnect 4-pin connector from Engine Coolant Temperature (ECT) sensor -G62- with Engine Coolant Temperature (ECT) sensor -G2- (arrow).







- Bridge terminals 3 + 4 of connector using respective adapter cables and observe indication on display.

If indication jumps to approx. 140.0 degrees C:
- End diagnosis and switch ignition off.
- Replace Engine Coolant Temperature (ECT) sensor -G62-.

WARNING:
- The cooling system is under pressure.
- Danger of scalding when opening.

- Erase DTC memory of Engine Control Module (ECM). Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If indication remains at approx. -40.0 degrees C:
- End diagnosis and switch ignition off.
- Check wires according to wiring diagram.

Continuation of test if indication is approx. 140.0 degrees C:







- Disconnect 4-pin connector from Engine Coolant Temperature (ECT) sensor -G62- with Engine Coolant Temperature (ECT) sensor -G2- (arrow).

If indication jumps to approx. -40.0 degrees C:
- End diagnosis and switch ignition off.
- Replace Engine Coolant Temperature (ECT) sensor -G62-:

WARNING:
- The cooling system is under pressure.
- Danger of scalding when opening.

- Erase DTC memory of Engine Control Module (ECM). Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If indication remains at approx. 140.0 degrees C:
- End diagnosis and switch ignition off.
- Check wires according to wiring diagram.

Checking wiring
- Connect test box to control module wiring harness. connect test box for wiring test. Test Box, Connecting For Wiring Test







- Check wires between test box and 4-pin connector for open circuit according to wiring diagram.

Terminal 3 + socket 93
Terminal 4 + socket 108

Wire resistance: max. 1.5 Ohms

- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+.

Specified value: Infinite Ohms

If no malfunctions are found in wires:







- Measure resistance at Engine Coolant Temperature (ECT) sensor -G62-, terminals C (signal) and D (Ground).







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 is in range A and corresponds to a resistance of 1.5 to 2.0 k Ohms
- 80 degrees C is in range B and corresponds to a resistance of 275 to 375 Ohms

If specified value is not obtained:
- Replace Engine Coolant Temperature (ECT) sensor -G62-.

WARNING:
- The cooling system is under pressure.
- Danger of scalding when opening.

- Erase DTC memory of Engine Control Module (ECM). Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If no malfunctions are detected in the wires and the resistance values are OK:
- Replace Motronic Engine Control Module (ECM) -J220-.
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