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TM9-2320-360-20-3
Section 4
TROUBLESHOOTING CHARTS
D. CHART -5 - “CHECK ENGINE” LIGHT ON AND NO ACTIVE CODE ON DDR
NOTE - This chart is only to be used if:
1) All basic mechanical checks and physical inspections have been performed with no problem found, and
2) Diagnosis of DDEC-III was started at step START-1, pg H-25 and you have now been referred here.
This is a digital output function.
STEP/SEQUENCE
RESULT
WHAT TO DO NEXT
C5-1
Check for Short
(Ckt #528)
l Turn ignition on. Observe “Check
Engine” light.
C 5-2
Check Light Status
l Plug in DDR.
l Select SWITCH/LIGHT STATS.
C 5-3
Check for Short
(Ckt #419)
l Turn ignition off.
l Disconnect the vehicle harness
connector at ECM.
l Turn ignition on (engine not running
while at same time observing
“Check Engine” light.
C 5-4
Force CEL On
l Install jumper wire between socket
B1 of vehicle harness
connector and a good ground.
l Observe “Check Engine” light.
Erratic or
intermittent
‘Check Engine” light.
Check for short to
ground on diagnostic request
line (ckt #528). Repair short.
Then go to C5-30.
"Check Engine”
light comes on
and stays on.
Go to C 5-2.
CEL reads on.
CEL reads off.
Go to C 5-4.
Go to C 5-3.
CEL driver line (ckt #419) is
shorted to ground. Repair short
Then go to C5-30.
“Check Engine”
light stays off.
Go to C 5-4.
“Check Engine”
light comes on
and stays on.
Go to C 5-5.
"Check Engine”
light stays off.
The ignition line (ckt #439) is
not correctly wired to CEL bulb.
See if bulb has been wired into
ignition line (#439) instead of
the proper #419 wire. Correct
problem. Then go to C5-30.
H-71
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