EDI DIAGNOSIS SERVICE MANUAL NUMBER 22
Page 5E-38 90-860074--1 FEBRUARY 2002
Timing Fault (Timing Advance Regulation)
Scan Code: P1230
Blink Code: 1321
Malfunction Indicator Lamp: OFF
75409
12
ECM
68
51
BLU
RED
1
2
45
23
REDRED
RED
a
b
c
d
e
e
e
a-Fuel Injection Pump
b-Timing Solenoid Valve
c-Harness Connector
d-Sensor Ground (–)
e-Battery Supply Voltage (1 of 3)
CIRCUIT DESCRIPTION:
Determining the proper fuel injection point (timing) depends on the quantity of fuel, engine
rpm and coolant temperature. The ECM controls the timing using the signal from the number
one instrumented injector and corrects the timing to the nominal timing rate. Adjustment of
pressure is carried out by an electric Timing Solenoid Valve which the ECM operates. When
the actuated timing advance (timing governing) is different from the setpoint (ECM stored
information) advance by more or less than 5°, this error will be set.
A failure in the Timing Fault circuit should set a Scan Code P1230.
CKT PIN
NAME
51 Solenoid
68 Battery Supply Voltage
45 Battery Supply Voltage
23 Battery Supply Voltage