Throttle Full Open Switch: Testing and Inspection

Idle and full throttle switches, checking and adjusting

The idle switch I signals the Digifant control unit that the throttle is fully closed for the following functions:
- fuel cut-off during deceleration
- idle speed stabilization
- ignition timing control during idle (DIS function) and deceleration

The full throttle switch II signals the Digifant control unit that the throttle is fully opened for the following function:
- injection quantity during full throttle enrichment

Voltage supply, checking

- disconnect throttle switch harness connector (arrow)
- connect test adaptor VAG 1501 to harness connector
- throttle switch connector remains open

- switch Fluke 83 multimeter to 20 Volt range
- connect multimeter to terminals 1 and 2 of VAG 1501 test adaptor using jumpers from VW 1594 adaptor kit
- switch ON ignition
- must be approx. 5 Volts

- switch OFF ignition
- connect multimeter to terminals 2 and 3 of VAG 1501 test adaptor using jumpers from VW 1594 adaptor kit
- switch ON ignition
- must be approx. 5 Volts

If voltage values are not obtained
- switch OFF ignition
- remove test adaptors and re-connect, harness connector to throttle switch
- determine break in wiring between throttle switch connector and ECU, repair or replace as necessary

If wiring OK
replace Digifant control unit (J 169)

Idle switch (F 60), checking and adjusting

- disconnect throttle switch harness connector (arrow)
- connect test adaptor VAG 1501 between throttle switch harness connector and throttle switch
- switch Fluke 83 multimeter to resistance range
- connect multimeter to terminals 1 and 2 of VAG 1501 test adaptor using jumpers from VW 1594 adaptor kit
- check idle switch I for continuity
- throttle closed=0 Ohms (continuity)
throttle open = Infinite resistance (open)

- attach protractor 3084 to throttle shaft using magnetic adaptor 3084/1
- fasten protractor pointer to throttle cable sleeve using circlip
- note protractor position via pointer
- open throttle valve approx. 10° then slowly and carefully close throttle until idle switch is activated (continuity)
- must be 1.0 ± 0.5° before idle speed stop

If NO
- adjust switch-on point by loosening throttle switch I and moving switch until throttle switch bracket is just resting against the throttle lever
- tighten switch and re-check

Full throttle switch (F 81), checking/adjusting

Requirement
- bypass valve adjustment OK, Testing and Inspection

- attach protractor 3084 to throttle shaft using magnetic adaptor 3084/1
- fasten protractor pointer to throttle cable sleeve using circlip
- using screwdriver, push throttle lever in direction of full throttle until lever 1 just starts to lift off by-pass valve lever 2 (arrow)
- with throttle in this position, set protractor disc to 0°
- close throttle approx. 10° then slowly open again until full throttle switch II just begins to activate (continuity)
- must occur at 4 ± 1°

If NO
- adjust switch-on point by loosening full throttle switch II and moving switch until specification is obtained
- tighten switch and re-check
- adjust throttle cable such that with accelerator pedal fully depressed, full throttle is just attained (1 mm maximum play at throttle lever)