DDEC TROUBLESHOOTING
91.2.4
Check for +5 Short to Ground
Perform the following steps to check for +5 short to ground.
1. Remove jumper wire.
2. Measure resistance between pins A and C of the TPS harness connector.
3. Measure resistance between pin C of the TPS harness connector and a good ground
(battery-).
[a] If the resistance measurement for both readings is greater than 1,000 , or open,
refer to section 91.2.7.
[b] If either resistance measurement is less than or equal to 1,000 , wire (#916) is
shorted to wire (#952), or battery ground. Repair the short and refer to section 91.2.9.
91.2.5
Vehicle Harness 5V Check TPS
Perform the following steps to check TPS.
1. Turn vehicle ignition switch OFF.
2. Reconnect the TPS connector.
3. Turn vehicle ignition switch ON.
4. Select Throttle Sensor percentage on the DDR.
5. Observe throttle percentage at both no throttle and full throttle (engine not running).
[a] If the percentage is between 0 and 100%, refer to section 91.2.7.
[b] If not getting a reading between 0 and 100%, refer to section 91.2.6.
91.2.6
Vehicle Harness 5V Check Throttle Position Sensor Connectors
Perform the following steps to check TPS connectors.
1. Turn vehicle ignition switch OFF.
2. Disconnect the TPS.
3. Inspect terminals at the TPS connectors (sensor side and harness side) for damage; bent,
corroded and unseated pins or sockets.
[a] If the terminals and connectors are not damaged, replace TPS. Refer to section 91.2.9.
[b] If the terminals and connectors are damaged, repair them. Refer to section 91.2.9.
91.2.7
Check ECM Connectors
Perform the following steps to check the ECM connectors.
1. Turn vehicle ignition switch OFF.
2. Disconnect the vehicle harness connector at the ECM (if not already disconnected).
All information subject to change without notice.
6SE497 9709 Copyright © 1997 DETROIT DIESEL CORPORATION
91-5
