Kohler Command PRO CH735 - Page 90

EFI SYSTEM-BOSCH
90
24 690 01 Rev. KKohlerEngines.com
● Code 51-Injector 1, "32 Pin" (MSE 1.1) Plastic-
Cased ECU only.
● Code 52-Injector 2, "32 Pin" (MSE 1.1) Plastic-
Cased ECU only.
● Code 55-MIL Light, "32 Pin" (MSE 1.1) Plastic-
Cased ECU only.
● Code 56-Pump Relay, "32 Pin" (MSE 1.1) Plastic-
Cased ECU only.
● MIL circuit grounded between light and ECU.
“35 Pin” (MA 1.7) Metal-Cased ECU: Pin circuit 31.
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Pin circuit
19.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Pin circuit
29.
● ECU
Diagnostic Aid #4 SPEED SENSOR (MIL does not turn
off during cranking). Indicates ECU is not receiving a
signal from speed sensor.
Possible causes:
● Speed sensor
● Speed sensor circuit problem
“35 Pin” (MA 1.7) Metal-Cased ECU: Pin circuits 3
and 21.
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Pin circuits
9 and 10.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Pin circuits
9 and 10.
● Speed sensor/toothed wheel air gap
● Toothed wheel
● Flywheel key sheared
● ECU
Diagnostic Aid #5 “FUEL PUMP” (fuel pump not turning
on)
Possible causes:
● Fuel pump fuse
● Fuel pump circuit problem
“35 Pin” (MA 1.7) Metal-Cased ECU: Circuits 43, 44,
and relay.
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuits
30, 87, and relay.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuits 30,
87, and relay.
● Fuel pump
Diagnostic Aid #6 “RELAY” (relay not operating)
Possible causes:
● Safety switches/circuit(s) problem
“35 Pin” (MA 1.7) Metal-Cased ECU: Circuits 41 and
41A.
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuit 3.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuit 25.
● Relay circuit(s) problem
“35 Pin” (MA 1.7) Metal-Cased ECU: Circuits 28, 41,
and 41A.
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuits 18,
85, 30, and 87.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuits
28,85, 30, and 87.
● Relay
● ECU grounds
● ECU
Diagnostic Aid #7 “IGNITION SYSTEM” (no spark)
Possible causes:
● Spark plug
● Plug wire
● Coil
● Coil circuit(s)
“35 Pin” (MA 1.7) Metal-Cased ECU: Circuits 1, 19,
40, 40A, 43, and relay.
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuits 22,
23, 65, 66, 30, and relay.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuits 30,
31, 65, 66, relay and relay circuit 30.
● ECU grounds
● ECU
Diagnostic Aid #8 “FUEL SYSTEM-ELECTRICAL” (no
fuel delivery)
Possible causes:
● No fuel
● Air in fuel rail
● Fuel valve shut off
● Fuel fi lter/line plugged
● Injector circuit(s)
“35 Pin” (MA 1.7) Metal-Cased ECU: Circuits 35,
35A, 45, and 45A.
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuits 16,
17, 45, and 45A.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuits
14,15, and 45.
● Injector
● ECU grounds
● ECU
Diagnostic Aid #9 “FUEL SYSTEM” (fuel pressure)
Possible causes for low fuel system pressure:
● Low fuel
● Fuel fi lter plugged
● Fuel supply line plugged
● Fuel pump
Possible causes for high fuel system pressure:
● Pressure regulator
● Fuel return line plugged or restricted.
Diagnostic Aid #10 “BASIC ENGINE” (cranks but will
not run)
Possible causes:
● Refer to basic engine troubleshooting charts within
Troubleshooting, Electronic Fuel Injection-ECH EFI,
and Electrical Systems.