Engine Control Module (ECM) Activation, Testing

Special tools and workshop equipment required 

• Test Box 105 Pin V.A.G 1598/42-1 and Test Adapter V.A.G 1598/47
• Vehicle Diagnostic, Testing and Information System VAS 5051 A with Multimeter Leads VAS 5051/7

• The Heater Control Module -J65- has a potentiometer installed. This potentiometer is operated via rotary switch for temperature preselect -A- and therefore transmits position of temperature dial to ECM.
  Fig 1: Identifying Heater Control Module And Switches

  Courtesy of AUDI OF AMERICA, LLC

-- On vehicles with diagram-mapped cooling, activation of Map Controlled Engine Cooling Thermostat -F265- is influenced by the respective ECM on certain engines. If rotary switch for temperature preselect -A- is located at Warm stop or closely in front of it, coolant temperature is reduced (limited to approximately 95 °C) to prevent excessive air blower temperatures from heater air vents. Check using Vehicle Diagnosis, Testing and Information System VAS 5051 in the "Guided Fault Finding" function (for respective ECM).

-- In vehicles with gasoline direct fuel injection engine FSI, mixture formation is influenced by respective ECM on certain engines. If rotary switch for temperature preselect -A- in area of Warm stop or closely in front of it, improved coolant heating (and thus better heating performance) is attained by departing the stratified charge range for engine mixture formation and the engine runs normally. Check using Vehicle Diagnosis, Testing and Information System VAS5051 in the "Guided Fault Finding" function (for respective ECM).

-- In vehicles for which this function is designated, a voltage of approximately 5 volts is supplied the ECM at connector -B- between terminal 1 and 10 with ignition switched on. Check using Vehicle Diagnosis, Testing and Information System VAS5051 in the "Guided Fault Finding" function (for respective ECM) and appropriate SYSTEM WIRING DIAGRAM.

-- A voltage between approximately 0.5 V (cold) and approximately 4.5 V (warm) is sent via terminal 2 inside the connector -B- to the heater control module -A- depending on the position of the temperature preset rotary switch -A- Each ECM knows the position of the temperature preset rotary switch -A- by this voltage. The ECM evaluates this voltage and then controls the coolant temperature and the mixture formation. Check using Vehicle Diagnosis, Testing and Information System VAS 5051 in the "Guided Fault Finding" function.