Ignition Retardation During Transmission Range Selection, Check
Ignition retardation during Transmission Range selection, checking
NOTE:
- The Engine Control Module receives the gear change signal via the transmission Control Module. The Engine Control Module then, depending on road and engine speeds, retards the ignition briefly. This reduces the torque and therefore the gear jolt.
- The VAG 1551 does not always recognise and Display the signal for torque reduction because it is sent for an extremely shod period.
- To check ignition retardation, the vehicle must be driven which requires a second technician to read the test equipment.
WARNING! Secure scan tool to rear seat and operate from this position.
Special tools, testers, measuring instruments and auxiliary items required
- Scan Tool VAG 1551 with cable VAG 1551/3B
- VAG 1598/22 Test Box
- Fluke 83 Multimeter
- VW 1594 Adaptor kit
- Wiring diagram
Test sequence
- Connect VAG 1551/1552 Scan Tool
- Start engine and let idle
- Press 0 and 1 buttons to select "Address word" 01 "Engine electronics"
Display will appear as shown
Rapid data transfer HELP
Select function XX
- Press 0 and 8 buttons to select Function 08: "Read measuring value block"
- Press Q button to enter input
Display will appear as shown
Read measuring value block HELP
Input Display group number XXX
- Press 1, 2 and 2 buttons to select "Display group 122"
- Press Q button to enter input
Display will appear as shown (1 to 4 = Display zones)
Read measuring value block 122 ->
1 2 3 4
- Perform test drive with 2nd technician to observe display.
- Check specifications in Display zone 4:
NOTE: It is possible that several gear changes must be performed before the Display in Display zone 3 jumps to 0 because the signal from the automatic transmission is very brief
If specification obtained
- Press -> button.
- Press 0 and 6 buttons to select Function 06: "End data transfer"
- Press Q button to enter input
- Switch OFF ignition. If display does not change:
- Connect VAG 1598/22 Test Box to Engine Control Module harness connector.
- Check wiring for open circuit between Test Box socket 23 and Automatic transmission using Wiring diagram.
- Wire resistance: Max. 1.5 Ohms