MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L>
13B-616
.
CIRCUIT OPERATION
•
Battery positive voltage is applied to the fuel
pump relay 1 (terminal 3) from the ignition switch-
IG.
Ground is provided through terminal 2 to chassis
ground.
•
When the ignition switch is turned to the "ON"
position, the battery positive voltage is applied to
the fuel pump relay 2 (terminal 1) from the fuel
pump relay 1 (terminal 1).
•
A battery positive voltage is applied on the fuel
pump relay 2 (terminal 3) from the ignition switch-
IG.
•
During cranking and while the engine is running,
the ECM <M/T> or PCM <A/T> turns the power
transistor in the ECM <M/T> or PCM <A/T> ON
to ground the fuel pump relay 2 coil. With this, the
fuel pump relay turns ON, and the battery positive
voltage is supplied to the fuel pump from the fuel
pump relay 2 (terminal 4).
.
TROUBLESHOOTING HINTS (The most likely
causes for this code to be set are:)
•
Malfunction of the fuel pump relay 1 and 2.
•
Malfunction of the fuel pump.
•
Improper connector contact, open or short-cir-
cuited harness wire.
•
Malfunction of the ECM <M/T> or PCM <A/T>.
DIAGNOSIS
Required Special Tool:
•
MB991502: Scan Tool (MUT-II)
STEP 1. Using scan tool MB991502, check actuator test
item 07: Fuel Pump.
CAUTION
To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Set scan tool MB991502 to the actuator test mode for item
07, Fuel Pump.
•
An operation sound of the fuel pump should be heard.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the fuel pump operating properly?
YES :
That this malfunction is intermittent. Refer to GROUP
00, How to Use Troubleshooting/Inspection Service
Points
NO :
Go to Step 2.
STEP 2. Check connector C-107 at fuel pump relay 1 and
connector C-105 at fuel pump relay 2 for damage.
Q: Is the connector in good condition?
YES :
Go to Step 3.
NO :
Repair or replace it. Refer to GROUP 00E, Harness
Connector Inspection
. Then confirm that the
malfunction symptom is eliminated.
AKX01177
16 PIN
MB991502
AB
AK103836
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
AE
CONNECTOR: C-105,C-107
C-107
JUNCTION BLOCK
HARNESS SIDE
CONNECTOR
C-105