Testing and adjusting idling speed switch — AUDI

AEW AHC AKG AKJ AKH
The idling speed switch is located on the rear of the throttle housing in the throttle valve potentiometer.

Start engine and run at idle.
Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit=>Page
01-2
.
Read measured value block (function 08) and select Display Group 04=>Page
01-108
.

Read measured value block 4
⇒
1
2
3
4
Display:

Check display in display zone 4.

Specified value: "Idle"

If "Part throt" is only displayed after long pedal travel, adjust idling speed switch.
Press accelerator pedal lightly (only a few millimetres).

Specified value: "Part throt"

If display does not change as described, check throttle cable adjustment or cruise control linkage.

=> 8-Cylinder Engine, Mechanics; Repair Group 20; Servicing throttle mechanism; Adjusting throttle cable.
8-Cylinder Engine, Mechanics
Servicing throttle mechanism
Adjusting throttle cable.

Check throttle valve unit for dirt.
If throttle cable adjustment and throttle valve unit are OK, check idling speed switch and wiring connections.

Adjusting idling speed switch

The throttle housing must be removed to adjust the idling speed switch.

Note:

Adjusting the idling speed switch also adjusts the throttle valve potentiometer.

Loosen both screws on throttle valve potentiometer.
Rotate the throttle valve potentiometer in direction of arrow until a stop can be felt, taking care not to move the throttle valve (throttle mechanism) when doing so.
Tighten throttle valve potentiometer in this position.

Testing wiring connections

Connect test box V.A.G 1598/19 to engine control unit wiring harness=>Page
24-15
.
Detach connector from throttle valve potentiometer.
Check following wires for continuity or short circuit:

Connector on wiring harness, contact · Test box V.A.G 1598/19 or engine control unit
4 · D11 (earth)
6 · B4

Eliminate wiring break or short circuit as necessary.

=> Current Flow Diagrams, Electrical Fault-Finding and Fitting Locations binder

Note:

Gold-plated contacts must always be used when replacing contacts in the throttle actuator connector.

If wiring connection is OK, test idling speed switch.

Testing idling speed switch

Connect test box V.A.G 1598/19 to engine control unit wiring harness=>Page
24-15
.
Throttle connector remains connected.
Connect hand multimeter between D11 and B4 and test for continuity.

Specified value: Continuity with throttle valve closed

Open throttle valve slightly.

Specified value: No continuity

If specified values are not reached, renew throttle valve unit.