Electrical Testing
Electrical Testing
=> [ Test Table ]
=> [ Shift Lock Solenoid, Checking ]
=> [ TCM and CAN Capable Control Modules, Checking Data Exchange ]
Special tools, testers and auxiliary items required
• Multi meter (VAG1526A)
• Adapter (VAG 1598/21)
• For testing, use multi meter (VAG1526A) or vehicle diagnostic testing and information system (VAS 5051 ). The charts contain the specific measurement methods which have to be set up before the corresponding measurements.
• The specified values given are valid for an ambient temperature of 0 °C to 40 °C.
• If the values measured deviate from the specified values, determine the malfunction using the wiring diagram.
• If the values measured show only a minor deviation from the specified values, clean cavities and plugs on the test equipment and test leads, repeat test. Before replacing the components in question, check their wires and connectors. In particular with specified values below 10 ohms repeat the resistance measurement on the component.
• The terminal numbers of the connector and the cavity numbers on the adapter (VAG 1598/21) test box match.
CAUTION!
In order to avoid destroying electronic components, the specific measurement range on the measuring equipment must be switched on before connecting the test leads.
Test Prerequisites
• Vehicle power supply OK.
• Power supply and fuses for particular system OK. Refer to
• Ground connections for transmission OK.
- Check ground connections for corrosion and faulty connection, repair as needed.
- Check battery ground strap and ground strap between battery and transmission.
Test Procedure
- Switch ignition OFF.
- Undo quick release fasteners - 2 - and - 3 - and remove sound deadening at rear. Sound deadening at front remains installed.
- Loosen cover for vehicle floor and heat shield above exhaust system in rear area of transmission. Push heat shield a little to one side.
- Where used, remove left inner - 2 - and right inner - 1 - vehicle floor covers.
- Unlock connector - A - in direction of - arrow - and disconnect it from transmission.
- Uncover wiring harness.
- Connect adapter (VAG 1598/21) to wiring harness to control module.
- Perform test as described in specific test chart.
Multiple Harness Connector (25 Pin Connector) for Transmission Control Module (TCM) (J217 ) (Cavities on Adapter (VAG 1598/21))
Test Table
Test Step 1-3:
* Power supply through terminal 87 is managed in different ways: On vehicles with the 2.4 liter engine through the ignition time delay relay for ignition cut off (J64); On all other gasoline engines through the Motronic Engine Control Module (ECM) power supply relay (J271).
Test Step 4:
Test Step 5:
* Corresponding terminal pinout on the ECM:
Shift Lock Solenoid, Checking
• This test must be performed if the specified values in the voltage measurement are not reached.
Special tools, testers and auxiliary items required
• Connector test kit (VAG 1594 A)
Test Sequence
- Remove cover for shift control mechanism.
- Disconnect harness connector at shift lock solenoid (N110) - A -.
- Attach multi meter for resistance measurement between contacts - B -.
• Specified value: 22.3 ± 1 ohms
If the specified value is not reached:
- Replace the shift lock solenoid.
TCM and CAN Capable Control Modules, Checking Data Exchange
• The exchange of data between the individual control modules is carried out by means of a bus system.
• Controller Area Network "(CAN) Bus" describes a system to carry and distribute data.
• The wiring connections between the control modules, over which the data are transmitted, are described as data lines.
• Data are transmitted serially, that means in sequence, over these data lines to the attached control modules (e.g. engine RPM, accelerator pedal position).
Bus System, Checking
In the (Diagnostic Trouble Code) DTC table you were instructed to inspect the exchange of data between the Transmission Control Module (TCM) (J217) and CAN capable control modules.
- Connect vehicle diagnostic testing and information system (VAS 5051). Refer to => [ VAS 5051, Connecting and Selecting Functions ] VAS 5051, Connecting and Selecting Functions, and select vehicle system "02 Transmission Electronics". Ignition must be switched on.
Display on vehicle diagnostic testing and information system (VAS 5051)
- Touch - 1 - diagnostic function "08 Read Measured Value Block".
Display on vehicle diagnostic testing and information system (VAS 5051)
1. Enter display group Max. input value = 255
• Measured value block 125 shows the participants on the data bus drive.
- On keypad enter - 2 - "125" for " Display group number 125" and confirm by touching Q button.
Display on vehicle diagnostic testing and information system (VAS 5051)
- Check displays in display fields - 1 - to - 4 -.
The display shows the control modules which are CAN capable with the Engine Control Module (ECM):
• Display 1: CAN capable control module is a participant on data bus
• Display 0 or no display: CAN capable control module is not a participant on data bus or not CAN capable
- End function "08 Read Measured Value Block" by touching arrow button.
- Touch "06 End output".
Display on vehicle diagnostic testing and information system (VAS 5051)
- In selection - 1 - touch diagnostic function " 00 Read DTC memory complete system".
• DTC memory of all systems in the vehicle capable of On Board Diagnostic (OBD) is read.
If a control module responds and identifies itself, the number of stored DTCs or "No DTC" is displayed on the screen.
Any stored DTCs in a system are shown in sequence. Then the vehicle diagnostic testing and information system (VAS 5051 ) sends the next address word.
If a DTC referring to "Data bus drive..." or "...CAN bus" is displayed:
- Check whether correct ECM and other CAN-capable control modules have been installed (Part No. and code).
If the correct control modules have been installed:
- Check whether multiple connectors for control module are fully seated.
If the multiple connectors are fully seated:
- Check CAN bus system.
Dual Wire Bus System, Checking
Communication takes place between two or more control modules over a "Dual Wire Bus System".
- Analyze DTCs stored in control modules.
• The analysis helps to pinpoint the wiring malfunction.
Example 1
Based on the DTCs entered in the DTC memories, it can be seen that control module 1 is not connected to control modules 2 and 3.
- Switch ignition OFF.
- Disconnect control modules connected by bus circuit and check whether a bus wiring connection has an open circuit.
- If no malfunction is found in bus wiring, replace control module 1.
Example 2
Based on the DTCs entered in the DTC memories, it can be seen that control module 2 is not connected to control modules 1 and 3.
- Switch ignition OFF.
- Disconnect control modules connected by the bus circuit and check whether a bus wiring connection has an open circuit.
- If no malfunction is found in bus wiring, replace control module 2.
Example 3
Based on the DTCs entered in the DTC memory, it can be seen that no transmission or reception activity is possible in any of the control modules.
- Switch ignition OFF.
- Disconnect control modules connected by bus circuit wiring and inspect bus wiring for a short circuit to B+ and to ground.
If you are unable to determine any cause in the bus wiring for the DTC "Data bus drive faulty", check to see whether one of the control modules is responsible for this DTC.
Test Prerequisite
• vehicle diagnostic testing and information system ( VAS 5051) connected and vehicle OBD selected. Refer to => [ VAS 5051, Connecting and Selecting Functions ] VAS 5051, Connecting and Selecting Functions.
All the control modules which use the CAN bus for communication are disconnected. The ignition is switched OFF.
- Connect one control module.
Display on vehicle diagnostic testing and information system (VAS 5051)
- Switch ignition ON.
- Touch appropriate vehicle system in Display - 1 -.
- Read DTC memory of control module just connected and delete it.
- Touch > button.
- In display touch - 1 - diagnostic function " 06 End output".
- Switch ignition OFF and ON again.
- Leave ignition switched ON for 10 seconds. Then, using scan tool, read DTC memory of control module just connected.
- If DTC "Data bus drive faulty" is read, control module just connected must be replaced.
- If DTC "Data bus drive not faulty" is read, connect next control module and repeat procedure.