GMC G Service Manual page 999

NO "SERVICE ENGINE SOON" LAMP
1. Disconnect the connector at the control module.
2. With ignition "ON", jumper a wire from terminal "D" on
the connector to ground. The lamp should illuminate.
• If the lamp does not illuminate, there is an
open from ignition (pink/black wire) to the lamp,
the lamp is inoperative, or there is an open from
the lamp to the module (brown/white wire).
AIR DIVERT
SOLENOID
v - -i —
..—
— --------
V pumi r H
V
V .
P M
A
SOLENOID
CONNECTOR
IGNITION
AIR DIVERT
SOLENOID
A B
SOLENOID
CONNECTOR
TO AIR CLEANER
OR SILENCER
V
= a s s r-
CHECK
I
VALVE
TO EXHAUST
B
PORTS
TO AIR CLEANER
OR SILENCER
V
TO EXHAUST
PORTS
Air Management System Chart — 5.7L Engine
CARBURETOR EMISSIONS 6E1-29
3. If the lamp illuminated in Step 2, jumper a wire from
terminal "D" on the connector to terminal "B" with the
ignition "ON". The lamp should illuminate.
• If the lamp does not illuminate, there is an open
circuit to ground at terminal "B" (black wire).
• If the lamp illuminates, replace control module.
SOLENOID
CONNECTOR
n
A B
— 39 PNK/BLK —
____ 150 BLK _
TACH INPUT SIGNAL
------ 121 WHT —
419 BRN/WHT —
------- 436 BRN "
SERVICE ENGINE
LAMP"
SOON
CONTROL
MODULE
L00674