Electronic Throttle Control Module: Testing and Inspection
Diagnostic Procedures
Throttle Valve Control Modules, Checking
• Use only gold-plated terminals when servicing terminals in harness connector of throttle valve control modules.
Function
The throttle valve activation occurs via an electric motor (throttle drive) in throttle valve control modules. This is operated by ECM according to specifications from two gas pedal position sensors.
Throttle Valve Control Module - 1 - (J338) components:
• Throttle Drive (for Electronic Power Control (EPC)) (G186)
• Throttle Drive Angle Sensor 1 (for Electronic Power Control (EPC)) (G187)
• Throttle Drive Angle Sensor 2 (for Electronic Power Control (EPC)) (G188)
Throttle Valve Control Module 2 (J544)- 4 - components:
• Throttle Drive 2 (G296)
• Throttle Drive Angle Sensor 2 (for Electronic Power Control (EPC)) (G297)
• Throttle Drive Angle Sensor 2 (for Electronic Power Control (EPC)) (G298)
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
• Battery voltage (both batteries) must be at least 11.5 Volts.
• All electrical consumers such as, lights and rear window defroster must be switched off.
• For vehicles with automatic transmission, selector lever must be in " P".
• Parking brake must be engaged.
• The Ground (GND) connections between engine and body must be OK.
• Throttle valve not damaged or contaminated
• Coolant temperature must be at least 20 °C => [ Diagnostic Mode 01 - Read Current System Data ] Diagnostic Modes 01 - 09, Diagnostic mode 1: Check measured values; PID 5, Coolant temperature.
• Fuses in right instrument panel fuse holder must be OK:
Right instrument panel fuse holder
Function Test
- Connect diagnostic tester.
- Switch ignition on.
- Under address word 33, select "Diagnostic mode 1: Check measured values".
- Select measured value "PID 17: Throttle valve position (absolute) ".
- Check specified value of throttle valve position (absolute) at idle stop:
- Slowly depress accelerator pedal up to Wide Open Throttle (WOT) stop while observing the percentage display. The percentage display must increase uniformly.
- Check specified value of throttle valve position (absolute) at Wide Open Throttle (WOT) stop:
- End diagnosis and switch ignition off.
If specifications are not obtained:
- Disconnect corresponding 6-pin connector from throttle valve control module to be tested:
• Cylinder bank 1 with cylinders 1 through 6 is located at right in direction of travel.
• Throttle Valve Control Module (J338) of cylinder bank 1 is located at left in direction of travel.
• Cylinder bank 2 with cylinders 7 through 12 is located at left in direction of travel.
• Throttle Valve Control Module 2 (J544) of cylinder bank 2 is located at right in direction of travel.
Check Resistance
- Check resistance of throttle valve drive in throttle valve control unit between terminals 3 + 5, specified value: 1.0 to 5.0 ohms
If specification is not obtained:
- Replace corresponding throttle valve control module.
- 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 voltage supply of throttle valve control modules and wiring to control module.
- Check Throttle Position sensor.
If no malfunction is detected in the voltage supply or wiring, replace the engine control module.
Voltage Supply and Wiring to Control Module, Checking
- Connect multimeter to terminals 2 + 6 of connector for voltage measurement.
- Switch ignition on. Specification: at least 4.5 V
- Switch ignition off.
If no voltage is present:
Cylinder bank 1
- Connect test box to Engine Control Module (ECM) (J623) wiring harness on connecting test box for wiring test, refer to Repair Manual,
Cylinder bank 2
- Connect test box to Engine Control Module (ECM) 2 (J624) wiring harness on connecting test box for wiring test,
Cylinder bank 1 and 2
- Check wires between test box and 6-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram: Terminal 1+Socket 92, Terminal 2+Socket 83, Terminal 3+Socket 117, Terminal 4+Socket 84, Terminal 5+Socket 118, Terminal 6+Socket 91, wire resistance: max. 1.5 ohms
- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+. Specification: infinite ohms
- 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 no fault is detected in the wiring:
- Check voltage supply of Engine Control Module (ECM) according to wiring diagram:
- 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.