Testing signals from and to automatic gearbox: Audi 1.9 TDI (1Z, AHU)

AHU
Special tools, testers and auxiliary items

Fault reader V.A.G 1551 (or vehicle system tester V.A.G 1552) with cable V.A.G 1551/1
Adapter set V.A.G 1594 A
Test box V.A.G 1598/18

A - Gearshift signal

This signal causes the injection quantity to be briefly reduced (torque reduction) during gearshifts in order to smooth out the jolts experienced when changing gear.

Notes:

A second mechanic is required to note the readings on the tester when the vehicle is moving.
Observe safety notes => Page
23-47
.

Connect fault reader V.A.G 1551 and select engine electronics control unit => Page
01-2
.

Read measured value block, Display Group 009, engine at idling speed => Page
01-58
.

Read measured value block 9
⇒
1
2
3
4
Indicated on display:

Check display in display zone 3.
Specification: 51 mg/H (mg/stroke)

Accelerate the vehicle from a stationary position with full throttle, but without using kick-down.
Read measured value block 9
⇒
1
2
3
4
Observe display zone 3 when vehicle changes into 2nd gear.
Specification: The display value should briefly fall below 51 mg/H.

Note:

Because of the lag in data transfer there might be a delay before the display reaches the specified value.

If the specification is not attained:

With the ignition switched off, connect test box V.A.G 1598/18 to connector for engine control unit => Page
23-45
.

Test for open circuit and short to earth or positive in the following wiring connections:

Test box / V.A.G 1598/18 / Socket · Automatic gearbox / control unit / Contact
18 · => Current flow diagrams, Electrical fault-finding and Fitting locations binder

Rectify any open/short circuit as necessary.

B - Accelerator pedal position signal

This signal is required for the calculation of gearshift points according to engine load.

The signal is monitored by the self-diagnosis function (fault memory, read measured value block) of the automatic gearbox control unit.

Testing signal

=> Automatic Gearbox 097; Repair group 01; Self-diagnosis of automatic gearbox 097
Automatic Gearbox 097
Self-diagnosis of automatic gearbox 097

=> Automatic Gearbox 01N; Repair group 01; Performing self-diagnosis
Automatic Gearbox 01N
Performing self-diagnosis

C - Engine speed signal

This signal is required for smoothing out the gearshifts.

Testing signal
=> Testing engine speed signal, Page
23-127
.

=> Automatic Gearbox 097; Repair group 01; Self-diagnosis of automatic gearbox 097
Automatic Gearbox 097
Self-diagnosis of automatic gearbox 097

=> Automatic Gearbox 01N; Repair group 01; Performing self-diagnosis
Automatic Gearbox 01N
Performing self-diagnosis

D - Kick-down signal

The signal is monitored by the self-diagnosis function (fault memory, read measured value block) of the automatic gearbox control unit.

Testing signal

=> Automatic Gearbox 097; Repair group 01; Self-diagnosis of automatic gearbox 097
Automatic Gearbox 097
Self-diagnosis of automatic gearbox 097

=> Automatic Gearbox 01N; Repair group 01; Performing self-diagnosis
Automatic Gearbox 01N
Performing self-diagnosis