Checking idling-speed stabilisation valve -N71 — AUDI

AEC
Special tools and workshop equipment required

V.A.G 1526 A
V.A.G 1527 B
V.A.G 1594 A
V.A.G 1598 with V.A.G 1598/5
VAS 5051 with VAS 5051/1 and VAS 5051/2

Fitting location => Exploded view of fitting locations - Page
24-5

Checking internal resistance

Switch off ignition.
Unplug connector -arrow- at idling-speed stabilisation valve.

Connect multimeter to valve for resistance measurement.
Specification: 7 ... 11 ω

Note:

Resistance is in lower tolerance range at ambient temperature and upper tolerance range when engine is warm.

If reading does not match specification:

Replace idling-speed stabilisation valve.

Mechanical checking

Remove idling-speed stabilisation valve.
Check for scoring of piston slide -arrow- (visual inspection).

Note:

To check freedom of movement, never use screwdriver or the like to move piston slide.

Attach connector to removed idling-speed stabilisation valve.
Switch on ignition.
Start final control diagnosis and actuate idling-speed stabilisation valve -N71 => Page
01-48
.
Check whether piston slide moves properly from stop to stop.

If scoring is found which impairs freedom of movement or if piston slide does not move freely (sticking, sluggish or not moving from stop to stop):

Replace idling-speed stabilisation valve.

If idling-speed stabilisation valve does not react during final control diagnosis:

Check power supply.

Checking power supply

Test requirements:

Fuse for idling speed stabilisation valve OK

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

Fuel pump relay OK; checking => Page
24-45

Note:

Idling speed stabilisation valve is supplied with power by fuel pump relay.

Connect up multimeter for voltage measurement as follows.

Connector / Contact · Measure to
1 · Engine earth

Briefly operate starter (engine may start).
Specification: approx. battery voltage

If reading does not match specification:

Use current flow diagram to eliminate open circuit in wiring/short circuit.

Checking actuation of idling-speed stabilisation valve

Connect up voltage tester V.A.G 1527 B between contacts 1 and 2.
Start final control diagnosis and actuate idling-speed stabilisation valve -N71 => Page
01-48
.
LED must flash

If LED does not flash or if it is permanently lit:

With ignition switched off, use adapter V.A.G 1598/5 to connect test box V.A.G 1598A to engine control-unit connector only (not to control unit) => Page
24-12
.
Check for open circuit and short to earth/positive in the following wiring.

Connector / Contact · Test box V.A.G 1598 A / Socket
2 · 4

If necessary, eliminate open circuit in wiring/short circuit.

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

If actuation and wiring are OK, but idling-speed stabilisation valve does not react, then valve has seized. Replace idling-speed stabilisation valve.