Testing drive range sensor on automatic gearbox: Audi 2.4 (AGA, AJG, ALF)

Note:

When the gear selector lever is in position P or N the drive range sensor (multi-function switch) -F125 on the gearbox switches contact 22 on the engine control unit to earth.
When a gear is engaged the switch is open and there is positive voltage at contact 22 on the engine control unit.

Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit with the "Address word" 01. When doing this the engine must be running at idling speed.
(Connecting fault reader and selecting engine electronics control unit => Page
01-3
.)

Rapid data transfer
HELP
Select function XX
Indicated on display:

Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

Read measured value block
Enter display group number XXX
Indicated on display:

Press keys 0, 5 and 6 to select Display Group 56 and confirm entry with Q key.

Read measured value block 56
⇒
1
2
3
4
Indicated on display:

Check display values for operating status.

Display zones
1 · 2 · 3 · 4
Display Group 56: Operating conditions
Display · xxxx rpm · xxxx rpm · x.xx g/s · 0 0 0 0
Indicates · Actual engine speed / (in steps of 10 rpm) · Specified engine speed / (in steps of 10 rpm) · Air mass / Idling speed control · Operating status
Range · min. 630 rpm / max. 680 rpm · min.: 650 rpm / max.: 1800 rpm · min. -1 g/s / max. 1 g/s · ---
Specification · xxxx rpm · xxxx rpm · -1....1 g/s · 0000 = selector lever in P or N / 0010 = selector lever in 2/3/4/R/D
Note · Engine speed readout same as in display zone 2 (±50 rpm) · Fixed value from / engine control unit · If readout does not match specification / => Page 24-125

Testing wiring

Switch off ignition.
Connect test box V.A.G 1598/22 to wiring harness for engine control unit => Page
24-22
.
Connect diode test lamp between contact 3 (terminal 30) and contact 22.

The diode test lamp should go out when a gear is engaged (2, 3, 4, R or D).

Move selector lever to position P or N.

The diode test lamp should light up.

If the diode test lamp does not light up:

Test for open circuit and short to positive or earth in wiring between gearbox control unit and contact 22 on engine control unit.

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

If there are no faults in the wiring, test the drive range sensor (multi-function switch).

=> Automatic gearbox 01V; Repair Group 01; Gearbox - Electrical test
Automatic gearbox 01V
Gearbox - Electrical test

Relevance of 4-figure display in Display Group 56

x · x · x · x · Display zone 4
0 · Air conditioner compressor off/on / 0 = air conditioner compressor off / 1 = air conditioner compressor on
0 · Selector lever in P or N / 0 = selector lever in P or N / 1 = selector lever in 2, 3, 4, R or D
0 · Air conditioner status, maximum hot/cold air output (A/C-High)
0 · Always 0