1A-54 Engine Control System
Unblinking CHECK ENGINE Lamp Check
Circuit Description
After DLC pins are shorted (i.e., the diagnostic switch is
turned on), the CHECK ENGINE lamp starts blinking to
indicate the engine and related systems are in faulty or
normal condition.
The ECM recognizes the ON signal from the diagnostic
switch and blinks the CHECK ENGINE lamp.
Diagnostic Aids
An intermittent may be caused by a poor connection, a
rubbed-through wire insulation, or a wire broken inside
the insulator. Check for the following conditions and, if
a fault is found, perform repair or replacement.
• Poor connection at ECM: Inspect harness
connectors for backed-out pins, improper mating,
broken locks, improperly formed or damaged pins,
and poor pin-to-wire connection.
• Damaged harness: Inspect the wiring harness for
rubbed-through wire insulation or wire broken
inside the insulator.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2: When even disconnecting the ECM does not turn off
the CHECK ENGINE lamp, the ground circuit of the
lamp is shorted.
ECM
(Engine
Control
Module)
CHECK
ENGINE
Lamp
LNW21ALF006001-X
121 120 119
95 87
118 117 116 115 114
113
109
0.25B
1.25B
1.25B
0.75B
0.5B
3W/G
2W/G
1.25W/R
0.5B/W
0.75B/O
1.25W/R
1.25W/R
0.5L/Y
99
0.5Y/B
0.5L/Y
0.5SB
0.5GR/W
112
88
Battery
DLC
Glow
Relay
Glow
Relay
IG
(ST)
IG
(ON)
SBF
50A
SBF
100A
3W/L
0.5B
SBF
50A
SBF
30A
SBF
60A
#19
15A
#22
10A
Main
Relay