Pontiac Fiero 1988 Service Manual page 465

6E2-A-10 DRIVEABILITY AND EMISSIONS - FUEL INJECTION (TBI)
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I.P. HARNESS CONNECTOR
15 WAY. (FRONT VIEW)
I
CM
J 1
I
' ORN 240
ORN 240
W10
WIS
FUSIBLE LINK
ECM FUSE
TO INJECTOR
•
BATTERY
IGNITION
SWITCH
GAGE FUSE SES LIGHT
DIAGNOSTIC TEST
ALDL CONNECTOR
o
V
B A
O
J
o
V
M
O
J
4 PNK/BLK 439
- BRN/WHT419
- WHT/BLK451
450
BLK/WHT
ENGINE
GROUND
ORN 461
W16
B22
B15
W12
B1
KEEP ALIVE
MEMORY (12 V)
IGN 12V
5 6V
SERIAL DATA
4-30-87
15-WAY I P. CONN.
7S3272-6E
4-9-87
CHAIT A-1
NO "SERVICE ENGINE SOON" LIGHT
2.5L "P " SERIES (TBI)
Circuit Description:
There should always be a steady "Service Engine Soon" light, when the ignition is "ON" and engine
stopped. Battery is supplied directly to the light bulb. The electronic control module (ECM) will control the
light and turn it "ON" by providing a ground path through CKT 419 to the ECM.
Test Description:
Numbers below refer to circled
numbers on the diagnostic chart.
1. Battery feed CKT 240 is protected by a fusible
link, at the battery.
2. Using a test light connected to 12 volts, probe each
of the system ground circuits to be sure a good
ground is present. See ECM terminal end view in
front of this section for ECM pin locations of
ground circuits.
Diagnostic Aids:
Engine runs OK, check:
• Faulty light bulb
• CKT 419 open
• Gage fuse blown. This will result in no oil, or
generator lights, seat belt reminder, etc.
Engine cranks, but will not run.
• Continuous battery - fuse or fusible link open
• ECM ignition fuse open
• Battery CKT 240 to ECM open
• Ignition CKT 439 to ECM open
• Poor connection to ECM