CHART - 7 - NO DATA TO DDR

TM 9-2320-364-20-1

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

Section IV. TROUBLESHOOTING CHARTS (Cont.)

D. CHART - 7 - NO DATA TO 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.

STEP/SEQUENCE

RESULT

WHAT TO DO NEXT

C 7-1

Read Codes on the

"Check Engine" Light

Unplug DDR.

Flashes

Go to C 7-4 (NOTE: If you wish to

Ignition on. Engine not running.

out codes.

bypass diagnosis of a potential

Depress and hold

data line of DDR problem for

diagnostic request switch.

now, go to CEL-3, page 2-549).

Read codes flashing out on

"Check Engine" light.

Does not flash

Go to C 7-2.

out codes.

C 7-2

Check Diagnostic

Request Circuit

Ignition on.

Switch reads off.

The diagnostic request circuit

Plug in DDR.

(#528) is open or ground is poor

Select VIEW CALIBRATION.

or open. Repair open wire or

Select ECM INs/OUTs to

bad ground. Then go to C 7-30.

determine port assigned to

"Diagnostic Request" (i.e., G1

- #528)

Go to SWITCH/LIGHT STATS.

Switch reads on.

Go to C 7-3.

Depress and hold diagnostic

request switch.

Read status of diagnostic

request.

C 7-3

Check ECM

Connectors

Check terminals at vehicle

Terminals

Replace ECM (para 7-57).

harness and 5-way power

and connectors

Then go to C 7-30.

harness connectors (both ECM

are okay.

and harness side) for damage;

bent, corroded, and unseated pins

Problem found.

Repair terminals/connectors

or sockets.

(para 7-101). Then go to C 7-30.

2-593