Throttle Body: Testing and Inspection
Components of the throttle valve control module -J338-:
- Throttle drive (power accelerator actuation) -G186-
- Angle sensor -1- for for throttle drive (power accelerator actuation) -G187-
- Angle sensor -2- for for throttle drive (power accelerator actuation) -G188-
NOTES:
- If the throttle valve control module is replaced, the new control module must be matched to the Engine Control Module (ECM). Testing and Inspection
- On vehicles with an automatic transmission, the Transmission Control Module (TCM) must also be adapted.
Special tools and equipment
- VAG1551 Scan Tool (ST) or VAG1552 mobile scan tool with VAG1551/3 adapter cable
- VAG1598/31 test box
- Multimeter (Fluke 83 or equivalent)
- VW1594 adapter set
- Wiring diagram
Test conditions
- Throttle valve not damaged or dirty.
- Automatic transmission selector lever in "P" or "N" position (if equipped)
- Coolant temperature at least 85 °C See display group 04, display field 3.
NOTE: Only gold plated contacts can be used to repair the contacts in the connector for the throttle valve control module.
- Connect VAG1551 (VAG1552) Scan Tool (ST). Testing and Inspection
- Switch ignition on and press buttons -0- and -1- to insert "Engine Electronics" address word 01.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08 and press -Q- button to confirm input.
Indicated on display
Read Measuring Value Block
Input display group number XXX
- Press buttons -0-, -6- and -2- to input display group number 62 (062) and press -Q- button to confirm input.
- Check angle sensor -1- for for throttle drive (power accelerator actuation) -G187- on idle speed stop in display field 1.
- Check angle sensor -2- for for throttle drive (power accelerator actuation) -G188- on idle speed stop in display field 2.
- Depress accelerator slowly until Wide Open Throttle (WOT) position and observe angles displayed in display fields 1 and 2.
The percentage displayed in display field 1 must rise continuously and evenly. The full tolerance range (3-93%) is not always displayed.
The percentage displayed in display field 2 must fall continuously and evenly. The full tolerance range (97-3%) is not always displayed.
NOTES:
- The display in display field 1 rises and the display in display field 2 falls because the potentiometers (angle sensors) in the throttle valve control modules run in opposite directions.
- This means that the voltage of one angle sensor moves toward 5 volts (the more the throttle valve is opened the higher the voltage; percentage increases), while the voltage of angle sensor 2 drops from 5 volts toward 0 volts (the more the throttle valve is opened the lower the voltage; percentage falls).
If the specified values are obtained:
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06 and press -Q- button to confirm input.
- Switch ignition off.
Continuation
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06 and press -Q- button to confirm input.
- Switch ignition off.
- Disconnect 6-pin harness connector from throttle valve control module (arrow).
- Measure resistance from throttle valve drive between terminals -3- and -5-
Specified value: 1.0-5.0 ohms
If the specified value is not obtained:
- Replace throttle valve control module -J338- See "Intake Manifold Upper Section, Disassembling and Assembling", item 10. Service and Repair
- Check DTC memory. If necessary, repair any malfunctions and erase DTC memory. Testing and Inspection
- Adapt Engine Control Module (ECM) to throttle valve control module. Testing and Inspection
- Display readiness code. Testing and Inspection
If DTC memory has been erased or the Engine Control Module (ECM) was disconnected from permanent battery (B+) voltage, the readiness code must be generated again. Testing and Inspection
If the specified value is obtained:
- Check voltage supply of throttle valve control module and wiring to control unit See below.
- Check accelerator pedal sensor.
If the voltage supply and wiring is OK:
- Replace Engine Control Module (ECM). Service and Repair
Checking voltage supply and wiring to control module
- Disconnect 6-pin harness connector from throttle valve control module (arrow).
- Connect multimeter to measure voltage at terminals -2- and -6-.
- Switch ignition on.
Specified value: min. 4.5 V
- Switch ignition off.
- Connect multimeter to measure voltage at harness connector terminal -2- and Ground.
- Switch ignition on.
Specified value: min. 4.5 V
- Switch ignition off.
If the specified values are not attained:
- Remove wiper arms and plenum chamber cover.
- Connect VAG1598/31 test box to Engine Control Module (ECM) wiring harness. Engine Control Module (ECM) is not connected by this action.
- Check wiring for open circuit between test box and harness connector terminals:
- Terminal 1 + socket 92
- Terminal -2- + socket 83
- Terminal -3- + socket 117
- Terminal -4- + socket 84
- Terminal -5- + socket 118
- Terminal -6- + socket 91
- Wiring resistance: max. 1.5 ohms
- Additionally, check wires for short to one another.
Specified value:Infinity ohms
- Check wiring additionally for short circuit to battery positive or Ground.
Specified value:Infinity ohms
If no malfunction is found in the wiring:
- Check Engine Control Module (ECM) voltage supply. Testing and Inspection