Map-Controlled Engine Cooling Thermostat, Checking
Map-Controlled Engine Cooling Thermostat, Checking
Special tools, testers and auxiliary items required
• Multimeter (VAG1526) or Multimeter (VAG1715)
• Connector test kit (VAG1594)
• Wiring diagram
Test Prerequisites
• Fuses in E-box (plenum chamber, left) must be OK:
• Battery voltage must be at least 11.5 volts.
• All electrical consumers such as, for example, lights and rear window defroster must be switched off.
• For vehicles with automatic transmission, selector lever must be in P.
• If vehicle is equipped with an A/C system, it must be switched off.
• Ground (GND) connections between engine and chassis must be OK.
• Ignition is switched off.
Test Sequence
- Disconnect 2-pin connector from Map Controlled Engine Cooling Thermostat (F265).
- Using adapter cables, measure heating wire resistance at Map Controlled Engine Cooling Thermostat (F265).Specified value at 25 °C: 14.0 to 18.0 ohms
If specified value is not obtained:
- Replace Map Controlled Engine Cooling Thermostat (F265).
- Erase DTC memory of Engine Control Module (ECM) => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory, Diagnostic mode 4: Reset/erase diagnostic data.
- Generate readiness code => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.
If specified value is obtained:
Checking Voltage Supply
- Connect multimeter to terminal 1 of 2-pin connector and Ground (GND) for voltage measurement.
- Switch ignition on.
Specified value: at least 11.5 V
- Switch ignition off.
If specified value is not obtained:
- Check wire via Fuse (S11) to Power Supply Relay (Terminal 30, B+) Relay 2 (J689) and Power Supply (Terminal 30, B+) Relay (J317) according to wiring diagram:
- Erase DTC memory of Engine Control Module (ECM) => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.
- Generate readiness code => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.
If specified value is obtained:
- Check Control Module Wires.
Control Module Wires, Checking
- Connect test box ( (VAG1598/42)) to Engine Control Module (ECM) (J623) wiring harness using adapter cable ( (VAG1598/39-1)) , connecting test box for wiring test.
- Check wire between test box and 2-pin connector for open circuit according to wiring diagram.
Terminal 2+socket 45
Wire resistance: max. 1.5ohms
- Also check wire for short circuit to vehicle Ground (GND) and to B+.
Specified value: infinit ohms
If no malfunctions are detected in the wires and the heating wire resistance was OK:
- Replace Engine Control Module (ECM) (J623) => [ Engine Control Modules, Replacing ] Engine Control Modules, Replacing.
- Generate readiness code => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.