91.2
TROUBLESHOOTING VEHICLE HARNESS +5 VOLT SUPPLY
3. Check terminals at the ECM vehicle harness connector (both the ECM and harness side)
for damage; bent, corroded and unseated pins or sockets (especially terminals #952, #916,
#417 and #510). Install new terminal if in doubt.
[a] If the terminals and connectors are not damaged, refer to section 90.2.2.
[b] If the terminals and connectors are damaged, repair them. Refer to section 91.2.9.
91.2.8
Check for Short to Battery (+)
Perform the following steps to check for a short to battery (+).
1. Turn vehicle ignition switch OFF.
2. Remove both fuses or circuit breakers to the ECM.
3. Disconnect the vehicle harness and the 5-pin power harness connectors at the ECM.
4. Measure resistance between sockets A3 and B3 on the vehicle harness connector.
5. Measure resistance between socket A3 on the vehicle harness connector and the battery (+).
[a] If the resistance measurement for all readings is greater than 1,000 , or open,
refer to section 91.2.7.
[b] If the resistance measurement is less than 1,000 , a short exists between the vehicle
+5 volt line (#916) and the lines where less than 1,000 was read (either circuit #240,
#241 or #439). Repair the short and refer to section 91.2.9.
91.2.9
Verify Repairs
Perform the following steps to verify repairs.
1. Turn vehicle ignition switch OFF.
2. Reconnect all connectors.
3. Reconnect fuses (or circuit breakers) if previously disconnected.
4. Turn ignition ON.
5. Clear codes.
6. If Check Engine Light (CEL) does not stay on, start engine and run for one minute.
7. Stop engine.
8. Read inactive codes with the DDR.
[a] If no codes are logged, troubleshooting is complete.
[b] If codes that brought you to this section are still logged, all system diagnostics
are complete. Review this section from the first step to find the error.
Refer to section 91.2.1.
[c] If codes except those which brought you to this section are logged, refer to section 9.1.
All information subject to change without notice.
91-6
6SE497 9709 Copyright © 1997 DETROIT DIESEL CORPORATION
