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5B.41
Section 5B
EFI Fuel System
5B
Code: 51 "32 Pin" (MSE 1.1) Plastic-
Cased ECU only.
Source: Injector #1 circuit open, shorted to
ground, or shorted to battery.
Explanation: Injector #1 is not functioning because
the circuit is open, shorted to ground,
or shorted to battery.
Expected Engine
Response: Engine will run very poorly with only
one cylinder functioning.
Possible Causes:
1. Injector Related
a. Injector coil shorted or opened.
2. Engine Wiring Harness Related
a. Broken or shorted wire in harness.
ECU pin 14 to injector pin 2. ECU pin 28 to
fuel pump relay pin 86. Note: after key-off then
key-on code 56 would be set also. Fuel pump
relay pin 87 to injector pin 1.
b. Open main fuse F1.
3. Fuel Pump Relay Related
a. Bad fuel pump relay.
Primary side functional but pin 30 to pin 87
remains open. Primary side pin 85 to pin 86 is
either open, or shorted during engine
operation. Note: after key-off then key-on
code 56 would be set also.
4. ECU Related
a. Circuit controlling injector #1 damaged.
b. Circuit controlling fuel pump relay damaged.
Code: 52 "32 Pin" (MSE 1.1) Plastic-
Cased ECU only.
Source: Injector #2 circuit open, shorted to
ground, or shorted to battery.
Explanation: Injector #2 is not functioning because
the circuit is open, shorted to ground,
or shorted to battery.
Expected Engine
Response: Engine will run very poorly with only
one cylinder functioning.
Possible Causes:
1. Injector Related
a. Injector coil shorted or opened.
2. Engine Wiring Harness Related
a. Broken or shorted wire in harness. ECU pin 15
to injector pin 2. ECU pin 28 to fuel pump relay
pin 86. Note: after key-off then key-on code 56
would be set also. Fuel pump relay pin 87 to
injector pin 1.
b. Opened main fuse F1.
3. Fuel Pump Relay Related
a. Bad fuel pump relay.
Primary side functional, but pin 30 to pin 87
remains open.
Primary side pin 85 to pin 86 is open or
shorted during engine operation. Note: after
key-off then key-on code 56 would be set also.
4. ECU Related
a. Circuit controlling injector #2 damaged.
b. Circuit controlling fuel pump relay damaged.
Code: 55 "32 Pin" (MSE 1.1) Plastic-
Cased ECU only.
Source: MIL (Diagnostic lamp) circuit open,
shorted to ground, or shorted to
battery.
Explanation: MIL is not functioning because the
circuit is open, shorted to ground, or
shorted to battery.
Expected Engine
Response: Engine will run normally if no other
errors are present.
Possible Causes:
1. MIL (diagnostic lamp) Related
a. MIL element opened or element shorted to
ground.
b. Lamp missing.
2. Engine Wiring Harness Related
a. Broken or shorted wire in harness.
ECU pin 29 to lamp open or shorted.
3. Vehicle Wiring Harness Related
a. Broken or shorted wire in harness.
Power lead to MIL open or shorted.
4. ECU Related
a. Circuit controlling lamp damaged.