check engine AUDI A4 1996 B5 / 1.G ATQ Engine Additional Signals Testing User Guide

24-192

Data transfer between Engine Control
Module (ECM) and CAN capable control
modules, checking


Notes:

Data exchange between individual control
modules occurs via a bus system.
The term "CAN-bus" refers to a system that
transports and distributes data.
The wire connections between the control
modules, via which data is transferred, are
referred to as data wires.
Data is transferred to the connected control
modules serially (one after the other) via these
data wires (i.e. engine speed, accelerator
position).

Checking bus system
The DTC table suggested checking the data
exchange between the Engine Control Module
(ECM) and CAN capable control modules.

-
Connect VAS5051 tester or VAG1551 scan tool
and select the control module for engine
electronics using "address word" 01 Page 01
-
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24-193

Rapid data transfer
HELP
Select function XX

When indicated on display:
- Press buttons -0- and -8- to select "Read Measuring Value Block" and
press -Q- button to confirm input.
Read Measuring Value Block
Q
Input displa
y group number XXX

When indicated on display:
Note:
Measuring value blocks 125 and 126 indicate the components that are
part of the powertrain data bus. - Press buttons -1-, -2- and -5- to select "display group number 125" and
press -Q- button to confirm input.
- Check indications in display fields 1 through 4.
CAN capable control modules connected to the Engine Control Module
(ECM) are indicated:

No indication: Control module not CAN capable
Indication 1: CAN capable control module is connected to databus
Indication 0: CAN capable control module is not connected to
databus
-
Press button.
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24-194

Rapid data transfer
HELP
Select function XX

When indicated on display:
- Press buttons -0- and -6- to select "End output" and press -Q- button to
confirm input.
Rapid data transfer
HELP
Insert address word XX

When indicated on display:
When a control module responds with its identification, the display
indicates the number of stored errors or indicates "no malfunctions
recognized".
DTCs stored in the system are indicated in sequence and printed out.
Then the VAG1551 scan tool sends the next address word. - Press button 0- twice to select "Automatic test sequence", address
word 00. Press -Q- button to confirm input.

DTC memory of all OBD capable systems in the vehicle will be
checked.
V.A.G - ON BOARD DIAGNOSTIC
HELP
1 - Rapid data transfer*2 - Blink code output*

The automatic test sequence is over when the following indication
appears on the display:
If a malfunction related to the"powertrain databus" or the "CAN-bus" is
indicated:
- Check whether the Engine Control Module (ECM) and other CAN
capable control modules installed are appropriate for this vehicle (part
no. and coding).
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