DTC 5-3-4

5-3-4 POWER STAGE GROUP D

Preconditions for DTC
^ If the ECM registers a fault in the circuits for the Malfunction Indicator Lamp (MIL), A/C relay, fuel pump or ignition power stage but cannot determine which circuit is faulty, DTC 5-3-4 is set.

Substitute values
^ Idle air trim inhibited.
^ Fuel trim inhibited.
^ Conditions for fuel shut-off changed.

Fault sources
^ MIL signal lead short circuited to voltage supply.
^ A/C relay signal lead short circuited to voltage supply.
^ Defective A/C relay.
^ Fuel pump signal lead short circuited to voltage supply.
^ Defective fuel pump relay.
^ Ignition power stage signal lead short circuited to voltage supply.
^ Defective ignition power stage.

Fault symptoms
^ Engine does not start, depending on fault source.
^ A/C does not function, depending on fault source.
^ MIL lights up when ignition is off, depending on fault source.

TESTING PROCEDURE





Starting the Engine
^ Try to START the engine.

If the engine starts:
- Check the MIL signal lead.
If the engine does not start:
- Check the fuel pump signal lead.





Checking the MIL Signal Lead
^ Connect the break-out box and check the ground connectors.
^ Connect the ECM.
^ Switch Ignition ON.





^ Connect a voltmeter between connectors #7 (ECM B7) and #28 (ECM B28) on the break-out box.

The voltmeter should show 0 - 2 Volts.

If the reading is OK:
- Check the A/C relay signal lead.
If the reading is incorrect:
- Check the lead between combined instrument panel B11 and ECM B7 for signs of short circuiting to voltage supply.





Checking the A/C Relay Signal Lead
^ A/C button ON.
^ Blower at low speed.
^ START the engine and let it run at idling speed.





^ Connect a voltmeter between connectors #40 (ECM B40) and #28 (ECM B28) on the break-out box.

The voltmeter should show 0 - 2 Volts.

If the reading is OK:
- The fault is intermittent. Proceed to: INTERMITTENT FAULT section below.
If the reading is incorrect:
- Check the A/C relay.





Checking the A/C Relay
^ Switch Ignition OFF.
^ Disconnect A/C relay (2/22).
^ A/C button ON.
^ Blower at low speed.
^ START the engine and let it run at idling speed.





^ Connect a voltmeter between connectors #40 (ECM B40) and #28 (ECM B28) on the break-out box.

The voltmeter should show 0 - 2 Volts.

If the reading is OK:
- Test with a new A/C relay.
If the reading is incorrect:
- Check the lead between A/C relay connector 4 and ECM B40 for signs of short circuiting to voltage supply.
If the car is equipped with ECC:
- Check also the lead between A/C relay connector and 4 and ECC control module A25 for signs of short circuiting to voltage supply.





Checking the Fuel Pump Signal Lead
^ Connect the break-out box and check the ground connectors.
^ Connect the ECM.
^ Switch Ignition ON.





^ Connect a voltmeter between connectors #27 (ECM B27) and #28 (ECM B28) on the break-out box.

The voltmeter should show approx. 1 Volt.

If the reading is OK:
- Check the ignition power stage signal lead.
If the reading is incorrect:
- Check the fuel pump relay.





Checking the Fuel Pump Relay
^ Switch Ignition OFF.
^ Disconnect fuel pump relay (2/23, position 103 in relay box).
^ Switch Ignition ON.
^ Connect a voltmeter between connectors #27 (ECM B27) and #28 (ECM B28) on the break-out box.

The voltmeter should show approx. 1 Volt.

If the reading is OK:
- Test with a new fuel pump relay.
If the reading is incorrect:
- Check the lead between fuel pump relay connector 4 and ECM B27 for signs of short circuiting to voltage supply.





Checking the Ignition Power Stage Signal Lead
^ Switch Ignition OFF.
^ Disconnect ignition power stage.
^ Switch Ignition ON.
^ Connect a voltmeter between connectors #11 (ECM B11) and #28 (ECM B28) on the break-out box.

The voltmeter should show 0 - 1 Volt.

If the reading is OK:
- Test with a new ignition power stage.
If the reading is incorrect:
- Check the lead between ignition power stage connector 4 and ECM B11 for signs of short circuiting to voltage supply.

INTERMITTENT FAULT





Checking the Leads and Connections
^ Check the lead between combined instrument panel B11 and ECM B7 for signs of intermittent short circuiting to voltage supply.
^ Check the lead between A/C relay connector 4 and ECM B40 for signs of intermittent short circuiting to voltage supply.
If the car is equipped with ECC:
Check also the lead between A/C relay connector 4 and ECC Control Module A25 for signs of intermittent short circuiting to voltage supply.
^ Check the lead between fuel pump relay connector 4 and ECM B27 for signs of intermittent short circuiting to voltage supply.
^ Check the lead between ignition power stage connector 4 and ECM B11 for signs of intermittent short circuiting to voltage supply.