Map-Controlled Engine Cooling Thermostat, Checking
Special tools and workshop equipment required
- Multimeter VAG1526 or Multimeter VAG1715
- Connector test kit VAG1594
- Wiring diagram
Test Prerequisites
- Fuses in E-box (plenum chamber, left) must be OK: Refer to SYSTEM WIRING DIAGRAM
- 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 Ω
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 4: Reset/erase diagnostic data.
-- Generate readiness code READINESS CODE .
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: refer to SYSTEM WIRING DIAGRAM
-- Erase DTC memory of Engine Control Module (ECM) DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
-- Generate readiness code READINESS CODE .
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. 1.5Ω
-- Also check wire for short circuit to vehicle Ground (GND) and to B+.
Specified value: ∞ Ω
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 .
-- Generate readiness code READINESS CODE .