Idle and Full Throttle Switches, Checking and Adjusting
IDLE AND FULL THROTTLE SWITCHES, CHECKING AND ADJUSTING
For vehicles with separate idle and full throttle switches.
For vehicles built after 10-90 starting with control units:
49 states: 8A0 907 404
California: 893 907 404Q
The function of the idle and full throttle switches can also be checked using the VAG 1551 diagnostic Tester, see functional check later in this section
- disconnect harness connector from idle/full throttle switch connector
- connect VAG 1501 test adaptor to idle/full throttle switch connector
- wiring harness connector remains open
Idle switch (F 60), checking and adjusting
- switch Fluke 83 multimeter to resistance range
- connect multimeter to adaptor leads 1 and 2 using jumpers from VW 1594 adaptor kit
- must be 0 Ohms
- open throttle slightly
- idle switch must switch OFF and resistance must increase to infinite Ohms
- close throttle slowly and while doing so check switching point of idle switch using feeler gauge
- throttle body free play between operating lever and throttle lever
- throttle body without free play between throttle lever and idle stop (limiter screw)
- switch point "a" must occur between 0.15 mm and 0.5 mm as measured between throttle valve lever and stop screw
- adjust switch point "a" if necessary, by loosening. and moving idle switch (F 60) until specification is obtained
- re-tighten idle switch mounting screws and re-check
NOTE: To ensure proper switching of idle switch, check operating levers for freedom of movement.
Full throttle switch (F 81), checking and adjusting
- connect multimeter between adaptor test leads 2 and 3 using jumpers fromVW 1594 adaptor kit
- must be infinite Ohms
- open throttle completely
- idle switch must switch on and resistance decrease to 0 Ohms
- mount 3084 protractor on throttle body shaft (2nd stage) and fasten using magnetic adapter 3084/1
NOTE: If throttle shaft (2nd stage) is attached with a mounting nut, place the protractor without 3084/1 magnetic adapter on the throttle shaft and if necessary remove the mounting nut
- open throttle fully by hand
- close throttle by approx. 30° then push slowly back in direction of full throttle stop (arrow), while doing so check switching point (0 Ohms) of full throttle switch 2
- switch point 10 ± 2° before full throttle stop
- adjust switch point if necessary by moving full throttle switch 2 as necessary, then re-check
The following procedures are for vehicles with idle switch, full throttle switch and throttle potentiometer contained in one assembly located below the throttle body.
Idle and full throttle switches, checking and adjusting
For vehicles built after 10-90 starting with control unit:
49 states 8A0 907 404
California:893 907 404Q
The idle and full throttle switches can also be checked using the VAG 1551 Diagnostic Tester, see functional check later in this section
- If the potentiometer is replaced in a vehicle. with an automatic transmission, the automatic transmission control unit must "learn" the voltage value of the new potentiometer by returning the system to its basic setting.
Idle and full throttle switches, checking
- connect VAG 1501 test adaptor to idle/full throttle switch connector (white)
- harness connector remains disconnected
- switch Fluke 83 multimeter to resistance range
- connect multimeter to adaptor leads 1 and using jumpers from VW 1594 adaptor kit
- must be 0 Ohms
- open throttle slightly
- idle switch must switch OFF and resistance increase to infinite Ohms
- slowly close throttle while checking switch point (0-Ohms) of idle switch with feeler gauge between throttle lever and idle stop (limiter screw)
- switch point "a"=0.15 mm to 0.5 mm before idle stop
- measure resistance between adaptor leads 2 and 3
- must be infinite Ohms
- open throttle completely
- full throttle switch must switch on and resistance decrease 0 Ohms
Idle and full throttle switches, adjusting
NOTE: The switching point of the idle switch is the only adjustment possible. The full throttle switch and potentiometer become adjusted as a result of adjusting the idle switch and are not adjusted separately.
- remove throttle body
- remove heat shield
- loosen potentiometer 1 (arrows)
- rotate and hold potentiometer first clockwise and then fully counterclockwise (carefully) up to stop
CAUTION: Turn potentiometer using very light force otherwise the throttle will open.
- tighten potentiometer in this position and check switching point as described in section "Air Flow Sensor Potentiometer, Checking and Adjusting". Testing and Inspection
Idle and full throttle switches, functional testing
For vehicles built after 10-90 starting with control unit:
49 states: A0 907 404
California: 893 907 404Q
Requirements
- A/C switched OFF
- selector lever in "P or N setting" (vehicles with automatic transmission)
- connect VAG 1551 Diagnostic connector using VAG 1551/1 adaptor cable as follows
- first connect black VAG 1551/1 connector to black diagnostic connector 1
- after "V.A.G SELF-DIAGNOSIS" display appears; connect white VAG 1551/1 connector to brown and/or white diagnostic connector 2
If display does not appear; do not connect white connector
- check voltage supply to VAG 1551 using wiring diagram
- switch ignition ON
- press 1 button to enter "rapid data transfer" mode
- press 0 and 1 buttons to enter engine electronics
- press 0 button to enter input
- press --> button
- press 0 and 8 buttons to enter function "read measurement-block"
- press Q button to enter input
- display will appear as shown
Read measurement block HELP
Input display group number XX
- press 0 button twice to select "Display group number 00"
- display will appear as shown
Read measurement block Q
Input display group number 00
- press Q button to enter input
- display shows channels 1 through 10
Read measurement block -->
1 2 3 4 5 6 7 8 9 10
- observe display value in channel 9
- displayed value must be 5
NOTE: The value displayed in channel 9 is the sum of the operating conditions present This sum is a result of adding together the various conditions present using the following assigned values:
Idle switch closed = 1
+ vehicles with manual or automatic transmission = 4
= displayed value in channel 9 5
- open throttle slightly
- idle switch must switch on and display in channel 9 must change to 4
Idle and full throttle switches open = 0
+ vehicles with manual or automatic transmission = 4
= displayed value in channel 9 4
- open throttle completely
- full throttle switch must switch and display value in channel must change to 6
Full throttle switch closed = 2
+ vehicles with manual or automatic transmission = 4
= displayed value in channel 9 6
NOTE: Read additional values in channel 9 in Function "Measurement block, reading".
If the required display values are obtained
- press --> button
- press 0 and 6 buttons to enter "end output" function
- press Q button to enter input
If required display values are not obtained
- perform electrical testing, Repair group D2 and if necessary replace CIS-E Motronic control unit (J 204)
- read and then erase Fault memory