DDEC TROUBLESHOOTING
86.3.6
Check for Short to Battery +
Perform the following steps to check for a short to battery.
1. Remove both fuses to the ECM.
2. Disconnect the vehicle harness and 5-way power connectors at the ECM.
3. Measure resistance between socket D3 on the engine harness connector and battery (+).
4. Measure resistance between socket D3 of the engine harness connector, and the 5-way
power harness sockets A and C.
[a] If the resistance measurement for all readings is greater than 100
or open,
refer to section 86.3.7.
[b] If the resistance measurement is less than or equal to 100 , a short exists between
the signal line (circuit #749) and battery (+). Repair short and reinsert fuses.
Refer to section 86.3.9.
86.3.7
Check ECM Connectors
Perform the following steps to check the ECM connectors.
1. Inspect terminals at the ECM connectors (both ECM and harness side) for damage: bent,
corroded, and unseated pins or sockets.
[a] If terminals and connectors are damaged, repair them. Refer to section 86.3.9.
[b] If terminals and connectors are not damaged, install a test ECM.
Refer to section 86.3.8.
86.3.8
Final Check
Perform the following steps to do a final check.
1. Reconnect all connectors.
2. Turn vehicle ignition ON.
3. Clear codes.
4. Start and run the engine for one minute.
5. Stop engine.
6. Check DDR for active codes.
[a] If no codes are logged, troubleshooting is complete.
[b] If active code 73/3 is logged, install a test ECM. Refer to section 86.3.9.
[c] If any codes except code 73/3 are logged, refer to section 9.1, to service other codes.
All information subject to change without notice.
6SE497 9709 Copyright © 1997 DETROIT DIESEL CORPORATION
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