Checking engine speed sender -G28 — AUDI

ALG
Special tools,
testers and auxiliary items required

V.A.G 1526 A
V.A.G 1594 A
V.A.G 1598/22

Notes:

The engine speed sender is a combined speed sender and reference mark sender. The engine cannot be started without a signal from the -G28 engine speed sensor. If the signal from the -G28 engine speed sensor fails while the engine is running, the engine will cut out immediately.
-G28 is provided with a shim to obtain a defined gap between -G28 and the sender wheel.
If the engine speed sender is fitted without a shim, the sender will be destroyed by the sender wheel.
For testing the operation of the engine speed sender, see also "Reading measured value block", Display Group 003, display zone 1.

Various engine speed senders, which can be distinguished by way of their connectors and contact assignments, have been fitted in the current series:

Rectangular plug for engine speed sender

Checking engine speed sender =>Page
28-18

Oval plug for engine speed sender
Checking engine speed sender =>Page
28-21

Checking engine speed sender with rectangular plug

Fitting location for sender and connector =>Page
24-7

Before carrying out the test, make sure that the sender is correctly installed and firmly seated.
Disconnect connector for engine speed sensor (identification: grey connector).

Connect multimeter between contacts 1 and 2 to measure resistance.
Specified value: 730 ...1000 ω

If the specification is not obtained:

Fit a new engine speed sender.

If the specification is obtained:

Connect multimeter between contacts 1 and 3 (earth) and 2 and 3 (earth) to measure resistance.
Specified value: infinity in each case ω (no continuity).

If the specification is not obtained:

Fit a new engine speed sender.

If the specification is obtained:

Connect test box V.A.G 1598/22 to wiring harness for engine control unit =>Page
24-24
.

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

Connector / contact · Test box V.A.G 1598/22 / socket
1 (signal) · 56
2 (earth) · 63
3 (screening) · 67

Rectify short circuit or open circuit if necessary.

If no fault has yet been found, check tightness of sender wheel at crankshaft.

Checking of sender wheel involves removing sender.

Slowly crank engine and check sender wheel for concentricity/tight fit.

Note:

It is normal for there to be a larger gap at a certain point in the sender wheel, as this is the reference mark.

If no faults have been found in any of the above tests, fit a new engine control unit =>Page
24-26
.

Checking engine speed sender with oval plug

Fitting location for sender and connector =>Page
24-7

Before carrying out the test, make sure that the sender is correctly installed and firmly seated.
Disconnect connector for engine speed sensor (identification: grey connector).

Connect multimeter between contacts 2 and 3 to measure resistance.
Specified value: 730 ...1000 ω

If the specification is not obtained:

Fit a new engine speed sender.

If the specification is obtained:

Connect multimeter between contacts 2 and 1 (earth) and 3 and 1 (earth) to measure resistance.
Specified value: infinity in each case ω (no continuity).

If the specification is not obtained:

Fit a new engine speed sender.

If the specification is obtained:

Connect test box V.A.G 1598/22 to wiring harness for engine control unit =>Page
24-24
.

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

Connector / contact · Test box V.A.G 1598/22 / socket
1 (signal) · 56
2 (earth) · 63
3 (screening) · 67

Rectify short circuit or open circuit if necessary.
If no fault has yet been found, check tightness of sender wheel at crankshaft.

Checking of sender wheel involves removing sender.

Slowly crank engine and check sender wheel for concentricity/tight fit.

Note:

It is normal for there to be a larger gap at a certain point in the sender wheel, as this is the reference mark.

If no faults have been found in any of the above tests, fit a new engine control unit =>Page
24-26
.