Inspection Procedure

DTC 78 Fuel Pump Control Circuit

INSPECTION PROCEDURE

1. CHECK FUEL PUMP OPERATION.
(a) Turn ignition switch ON.



(b) Using special service tool (SST #09843-18020) or a jumper wire, connect terminals +B and FP of data link connector (DLC1).



(c) Check that there is pressure in the hose from the fuel filter.

OK if pressure can be felt.

- If OK proceed to step 2.
- If not OK proceed to step 3.

2. Check for open and short in harness and connector between terminals +B and FP of DLC1 and the corresponding terminals of the fuel pump ECU.
- If OK proceed to step 5.
- If not OK repair or replace harness or connector.

3. Check voltage of terminal +B of DLC1.
(a) Turn ignition switch ON.



(b) Measure voltage between terminal +B of DLC1 and body ground.

Voltage: 9 - 14 volts

- If OK proceed to step 4.
- If not OK check for ECM power source circuit [1], and check for open in harness and connector between terminal +B of DLC1 and main relay.

[1] (Refer to the Non-Trouble Code Charts)
ECM Power Source Circuit

4. Check for open and short in harness and connector between terminal FP of DLC1, fuel pump and body ground.
- If OK repair or replace fuel pump.
- If not OK repair or replace harness or connector.

5. Check voltage between terminals 5 (FPC) and 8 (E) of fuel pump ECU connector.
(a) Remove the LH quarter trim panel.
(b) Disconnect fuel pump ECU connector.



(c) Measure voltage between terminals 5 (FPC) and 8 (E) of fuel pump ECU connector when ignition switch is turned to start.

Voltage: 4.5 - 5.5 volts

- If OK replace fuel pump ECU.
- If not OK proceed to step 6.

6. Check for open in harness and connector between terminal FPC of engine control module and terminal 5 (FPC) of fuel pump ECU, terminal 8 (E) of fuel pump ECU and body ground.
- If OK proceed to step 7.
- If not OK repair or replace harness or connector.

7. Check for open and short in harness and connector between terminal DI of engine control module and terminal 6 (DI) of fuel pump ECU.
- If OK check and replace ECM.
- If not OK repair or replace harness or connector.