With Manufacturer's Scan Tool
Modulating Piston Displacement Sensor -G149- And Quantity Adjuster -N146-, Checking
The quantity adjuster is an electro-magnetic swivelling positioner which is controlled by the ECM via a directed duty cycle (on-off ratio). The eccentric shaft on the quantity adjuster moves the modulating piston on the high pressure piston thereby regulating the quantity of fuel injected.
The modulating piston displacement sensor - G149- informs the ECM of the position of Quantity Adjuster -N146- there determines the amount injected.
NOTE: Only gold-plated contacts must be used when repairing terminals in the connector to injection pump quantity adjuster.
Special tools and equipment
- VAG 1551/1552 Scan tool with adapter cable
- VAG 1551/3
- Test box VAG 1598/31
- Hand multimeter VAG 1526 or multimeter VAG 1715
- Adapter set VAG 1594
- Wiring diagram
Test sequence
- Connect Scan Tool VAG 1551 (VAG 1552) and select engine electronics control unit with the "Engine electronics" address word 01. When doing this the engine must be running at idling speed. (Connecting Scan Tool and selecting engine electronics control unit. [1][2][3]Connecting VAG 1551 Scan Tool)
Indicated on display:
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select "Read measured value block" function 08 and confirm entry with -Q- button.
Indicated on display:
Read measured value block
Enter display group number XXX
- Press buttons -0-, -0- and -1- for "Display group number 1" and confirm entry with -Q- button.
Indicated on display:
Read measured value block 1 ->
840 rpm 6.5 mg/H 1.480 V 87.3 degree C
- Check coolant temperature in display field 4.
Specification: at least 85 degree C
Continue with check only when coolant temperature is attained.
- Check voltage supply from modulating piston displacement sensor in display field 3.
Specification: 1.450 to 2.000 V
Read measured value block 1 ->
840 rpm 6.5 mg/H 1.480 V 87.3 degree C
- If specification is not obtained, check modulating piston movement sender and quantity adjuster as described in following steps:
Checking Modulating Piston Displacement Sensor -G149-.
- Press the -> button.
- Press buttons -0- and -6- for the function "End output" and confirm entry with the -Q- button.
- Switch ignition off.
- Disconnect the 10-pin connector for the metering unit (connector to metering unit in injection pump) -arrow-.
- Measure resistance between connector terminals 1 + 2 and 2 + 3.
Specification: 4.9 to 7.5 Ohm
If the specification is not obtained:
- Replace injection pump.
- Check DTC memory and, if necessary, repair any malfunctions and then erase. [1][2]Reading Diagnostic Trouble Codes
- Read-out the readiness code. If the DTC memory has been erased or the Diesel Direct Fuel Injection Engine Control Module -J248- was disconnected from permanent battery positive (B+), the readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes
If the specification is obtained:
- Remove wiper arms and plenum cover:
- Connect test box VAG 1598/31 to control module wiring harness.
- Check wiring between test box and connector for open circuit according to wiring diagram.
Terminal 1 + socket 108
Terminal 2 + socket 106
Terminal 3 + socket 99
Wire resistance: max. 1.5 Ohm
- Check wires for short to one another, to vehicle Ground and to battery positive (B+).
Specification: Infinite Ohm
If no fault is detected in the wiring:
- Replace Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248-.
Checking Quantity Adjuster -N146-
- Press the -> button.
- Press buttons -0- and -6- for the "End data transfer" function and confirm input with the -Q- button.
- Switch off ignition.
- Disconnect 10-pin connector from quantity adjuster (connector to injection pump) -arrow-.
- Measure resistance between connector terminals 5+6.
Specification: 0.5 to 2.5 Ohm
If the specification is obtained:
- Replace injection pump.
- Check DTC memory and, if necessary, repair any malfunctions and then erase. [1][2]Reading Diagnostic Trouble Codes
- Read-out the readiness code. If the DTC memory has been erased or the Diesel Direct Fuel Injection Engine Control Module -J248- was disconnected from permanent battery positive (B+), the readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes
If the specification is not obtained:
- Remove wiper arms and plenum cover.
- Connect test box VAG 1598/31 to control module wiring harness.
- Check wiring between test box and connector for open circuit according to wiring diagram.
Terminal 5 + sockets 1 and 2
Terminal 6 + sockets 121 and 116
Wire resistance: max. 1.5 Ohm
- Check wires for short to one another, to vehicle Ground and to battery positive (B+).
Specification: Infinite Ohm
If wiring and the resistance measurement values are OK:
- Replace Diesel Direct Fuel Injection Engine Control Module -J248-.