With Generic Scan Tool
Check Motronic Engine Control Module (ECM) Power Supply Relay -J271- And Activation
Special Tools and Equipment
- VAG1526A multimeter
- VAG1594A connector test kit
- VAG1598/31 test box
NOTE: The Motronic Engine Control Module (ECM) voltage supply relay -J271- supplies voltage to the ignition coils with power output stages and the Engine Control Module (ECM) at pin 121.
Test requirement:
- Ignition switched off.
Test sequence
- Remove cover -1- in engine compartment (left side).
- Remove coolant reservoir (arrow).
- Disconnect electrical wire from Engine Coolant Level (ECL) Warning Switch -F66- at bottom of reservoir.
- Lay aside coolant reservoir with connected coolant hoses -1- to -3-.
- Remove bolts (arrows) on cylinder head at left.
- Disconnect 4-pin harness connectors -4- to -6- at ignition coils.
NOTE: For further testing, connect the multimeter to harness connector in place of an ignition coil.
- Connect multimeter for voltage measurement as follows.
Harness connector Measure to
Terminal
1 Engine Ground (GND)
- Switch ignition on.
- Specified value: approx. battery voltage
- Switch ignition off.
If specified value is not obtained:
- Pull off rubber seal of plenum chamber cover in direction of arrow.
- Remove cover -1- toward front.
- Remove cover for E-box, plenum chamber (arrows).
- Pry off Engine Control Module (ECM) retaining bracket (arrow) using a screwdriver and set control module aside.
- Disconnect voltage supply relay -3-.
- Check the following wire connection for open circuit according to wiring diagram:
Relay carrier in E-box, plenum Harness connector at
chamber, position 2 ignition coils
Terminal Terminal
8 1
- Specified value: Wire resistance max 1.5 Ohms
- If necessary, repair wire connection.
If no malfunctions are found in wires:
- Check voltage supply of Motronic Engine Control Module (ECM) voltage supply relay -J271-.
- Check activation of Motronic Engine Control Module (ECM) voltage supply relay -J271-.
Checking voltage supply
- Connect multimeter for voltage measurement as follows.
Relay carrier in E-box, plenum Measure to
chamber, position 2
Terminal
1 Engine Ground (GND)
2 Engine Ground (GND)
- Specified value: approx. battery voltage
If specified value is not obtained:
- Check wire connections for open circuit according to wiring diagram:
- Specified value: Wire resistance max 1.5 Ohms
Checking activation
- Connect multimeter for voltage measurement as follows.
Relay carrier in E-box, plenum Measure to
chamber, position 2
Terminal
4 B+
- Switch ignition on.
- Specified value: approx. battery voltage
- Switch ignition off.
If specified value is not obtained.
- Connect test box to wiring harness of Engine Control Module (ECM); ECM is not connected. Test Box, Connecting For Wiring Testing
- Check the following wire connection for open circuit according to wiring diagram:
Relay carrier in E-box, plenum Test box
chamber, position 2
Terminal Socket
4 23
- Specified value: Wire resistance max 1.5 Ohms
- Also check the wire for short circuit to B+ and Ground (GND).
- Specified value: Infinity Ohms (no continuity)
- If necessary, repair wire connection.
If no malfunctions are detected:
- Replace Motronic Engine Control Module (ECM) voltage supply relay -J271-.