MAP Controlled Thermostat, Checking
Diagnostic Procedures
MAP Controlled Thermostat, Checking
Special tools, testers and auxiliary items required
• Hand multimeter (V.A.G 1526) or Multimeter (V.A.G 1715)
• Test adapter kit (V.A.G 1594)
• Wiring diagram
Test conditions
• The Ground (GND) connections between engine and body must be OK.
• Ignition switched off.
Fuses in right instrument panel fuse holder must be OK:
Right instrument panel fuse holder
Test Sequence
- Remove intake manifold upper part (along with both intake manifold side parts).
• Seal the intake channels in cylinder head using a clean rag.
- Remove 2-pin connector from Map Controlled Engine Cooling Thermostat (F265) - 2 -.
Check resistance
- Check resistance between terminals of thermostat. Specification: 14.0 to 18.0 ohms
If specification is not obtained:
- Replace Map Controlled Engine Cooling Thermostat (F265), refer to Repair Manual
- Erase DTC memory of Engine Control Module => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09, Diagnostic mode 4: Reset/erase diagnostic data.
- Generate readiness code => [ Readiness Code, Generating ] Monitors, Trips, Drive Cycles and Readiness Codes.
If specification is obtained:
- Check wires to control module according to wiring diagram.
Check wires to control module
- Connect test box to Engine Control Module (ECM) (J623) wiring harness on connecting test box for wiring test, refer to Repair Manual,
- Check wire between test box socket 116 + terminal 2 of 2-pin connector for open circuit according to wiring diagram. Wiring resistance: max. 1.5 ohms
- Check the wire for short circuit to B+ and Ground (GND). Specification: infinite ohms
- Check wire between 1-pin connector terminal 2 and Motronic Engine Control Module (ECM) Power Supply Relay (J271) for open circuit according to wiring diagram. Wiring resistance: max. 1.5 ohms
- Erase DTC memory of Engine Control Module (ECM) => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09, Diagnostic mode 4: Reset/erase diagnostic data.
- Generate readiness code => [ Readiness Code, Generating ] Monitors, Trips, Drive Cycles and Readiness Codes.
If no malfunctions are detected in the wires and the resistance value is OK:
If no malfunction is detected in the wiring, replace the engine control module.