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5B.42
Section 5B
EFI Fuel System
Code: 56 "32 Pin" (MSE 1.1) Plastic-
Cased ECU only.
Source: Fuel pump relay circuit open, shorted
to ground, or shorted to battery
Explanation: Fuel pump, ignition coils, and fuel
injectors will not function because the
fuel pump relay circuit is either open,
shorted to ground, or may be “on”
continuously if shorted to battery.
Expected Engine
Response: Engine will not run, or fuel pump will
continue to run when switch is off.
Possible Causes:
1. Fuel Pump Relay Related
a. Bad fuel pump relay.
Primary side open or shorted.
2. Fuel Pump Related
a. Fuel pump open or shorted internally.
3. Engine Wiring Harness Related
a. Fuel pump fuse F1 open.
b. Broken or shorted wire in harness.
ECU pin 28 to fuel pump relay pin 86.
Ignition switch to fuel pump relay pin 85.
4. ECU Related
a. Circuit controlling fuel pump relay damaged.
Code: 61
Source:
Explanation: Denotes the end of fault codes. If
signaled first, no other fault codes are
present.
Troubleshooting Flow Chart
The following flow chart (on page 5B.43) provides an
alternative method of troubleshooting the EFI system.
The chart will enable you to review the entire system in
about 10-15 minutes. Using the chart, the
accompanying diagnostic aids (listed after the chart),
and any signaled fault codes, you should be able to
quickly locate any problems within the system.