TK. MFI #20 No Pump Relay Control Signal

TK. MFI#20

MFI#20 No pump relay control signal




Fault message conditions:
The fault message is logged if voltage is above 3 V.

Causes of fault:
Break between MFI#9 and the system relay.
System relay defective.

Fault symptoms:
The engine will not start.
If the fault is intermittent the engine will stop or run rough.

TK1




Volvo ST, Test box
- Disconnect the ST in accordance with QA2. QA. Connecting The Volvo Scan Tool (ST)
- Connect the test box to MFI and check the GND points in accordance with P1-P2. P. Test Box, Signal Description
^ Continue with Checking the power supply TK2.

TK2




Checking the power supply
- Connect the control module to the test box.
- Install the fuse.
Connect a voltmeter between MFI#20 and MFI#5.
- Try to start the engine.
The voltmeter should read approx. 1 V when the starter motor is operating or the engine running.

If this value is OK:
^ Check the wiring to MFI#9 TK4.

If the reading is incorrect:
^ Test the system relay TK3.

TK3




Testing the system relay
- Try using a new system relay.
Connect a voltmeter between MFI#20 and MFI#5.
- Try starting the engine.
The voltmeter should read approx. 1 V when starter motor is operating or the engine running.

If this value is OK:
^ The system relay was sluggish.

If the value still deviates:
^ Check the wiring to MFI#9 TK4.

TK4




Checking the wiring to MFI#9
- Disconnect the IAC valve to isolate MFI#33.
- Ignition on.
Connect a voltmeter between MFI#9 and MFI#5.
The voltmeter should read battery voltage.

If this value is OK:
^ Check for loose contacts in the wiring TK5.

If the reading deviates:
^ Check the wiring between MFI#9 and the system relay for breaks in accordance with NA2. NA. Checking the Wiring

TK5




Checking for loose contacts in the wiring
- The IAC valve disconnected.
- Ignition on.
Connect a voltmeter between MFI#9 and MFI#5.
The voltmeter should read battery voltage.
Check that the voltage does not drop to 0 when carrying out a Check for loose contacts in accordance with NA5. NA. Checking the Wiring

If the reading deviates:
Intermittent break:
^ Repair the wiring.

If this value is OK
^ Try using a new control module.