CHART - 5 - "CHECK ENGINE" LIGHT ON AND NO ACTIVE CODE ON DDR

TM 9-2320-364-20-1

2-14. DDEC III/IV TROUBLESHOOTING (CONT).

Section IV. TROUBLESHOOTING CHARTS (Cont.)

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/IV was started at step START-1, pg 2-539, and you have now been referred here.

This is a digital output function.

STEP/SEQUENCE

RESULT

WHAT TO DO NEXT

C 5-1

Check for Short

(Ckt #528)

Turn ignition on. Observe "Check

Erratic or

Check for short to

Engine" light.

intermittent

ground on diagnostic request

"Check Engine" light.

line (ckt #528). Repair short.

Then go to C 5-30.

"Check Engine"

Go to C 5-2.

light comes on

and stays on.

C 5-2

Check Light Status

Plug in DDR.

CEL reads on.

Go to C 5-4.

Select SWITCH/LIGHT STATS.

CEL reads off.

Go to C 5-3.

C 5-3

Check for Short

(Ckt #419)

Turn ignition off.

"Check Engine"

CEL driver line (ckt #419) is

Disconnect the vehicle harness

light comes on

shorted to ground. Repair short

connector at ECM.

and stays on.

Then go to C 5-30.

Turn ignition on (engine not

running) while at same time

observing "Check Engine" light.

"Check Engine"

Go to C 5-4.

light stays off.

C 5-4

Force CEL On

Install jumper wire between socket

"Check Engine"

Go to C 5-5.

B1 of vehicle harness

light comes on

connector and a good ground.

and stays on.

Observe "Check Engine" light.

"Check Engine"

The ignition line (ckt #439) is

light stays off.

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 C 5-30.

2-585