Throttle Position Switch: Testing and Inspection

Checking and Adjusting the Throttle Position Switch LH 2.2, 2.4 and 2.4.1

Tools:
- Multimeter
- Breakout Box 86 11 006
- Test cable 86 11 410

A faulty or incorrectly adjusted throttle position switch will cause difficulty in adjusting idling speed correctly. In addition, it may also give rise to fuel enrichment problems or ignition problems.

Always carry out idling speed adjustment before adjusting the throttle position switch, see "Adjustment of idling speed". ZZZZZZ




1 Check that the circuit is closed between pins 2 and 18 in the closed throttle position and between pins 3 and 18 in the wide open throttle position. If it is not, change the throttle position switch.

2 Unplug the LH control module connector. Plug in the breakout Box.

3 Connect the multimeter to:
LH 2.2
pin 3 and ground
LH 2.4 and LH 2.4.1
pin 2 and ground

Check that the circuit is closed.

Alternatively, an ISAT scan tool can be used for M1990- LH 2.4, 2.4.1 and 2.4.2. Select command code 201.

Component and signal testing with the self-diagnostics function and LH tester can also be used.

4 Rotate the throttle butterfly and check the reading on the multimeter. If in proper working order, the circuit should be broken as soon as the throttle butterfly leaves the closed throttle position. If this does not happen, adjust the position of the throttle butterfly (closed in the closed throttle position).

Check that the setting is correct. When the throttle lever is actuated, a metallic clicking sound should be heard from the switch when it leaves the closed throttle position.

5 If the circuit is not closed, check:
LH 2.2
the lead from pin 3 of the connector to pin 1 of the position switch (203) and the lead between pin 2 of the position switch and ground.
LH 2.4 and LH 2.4.1
the lead between pin 2 of the connector and pin 1 of the position switch (203) and the lead between pin 2 of the position switch and ground.




6 Connect the multimeter to:
LH 2.2
pin 12 and ground
LH 2.4 and LH 2.4.1
pin 3 and ground

If the position switch is in proper working order the circuit should close when the throttle butterfly is rotated through 720, i.e. near the wide open throttle position.

7 If this does not happen, check:
LH 2.2
the lead between pin 12 of the connector and pin 3 of the position switch (203)
LH 2.4, 2.4.1
the lead between pin 3 of the connector and pin 3 of the position switch (203).

If the wiring is OK but the position switch does not work properly, change the position switch.