DDEC TROUBLESHOOTING
21.3 TROUBLESHOOTING FLASH CODE 21
The following procedure will troubleshoot Flash Code 21.
21.3.1
Multiple Code Check
Perform the following steps to check for multiple codes.
1. Turn ignition ON.
2. Plug in DDR.
3. Read active codes.
[a] If active code 91/3 and no other active codes are logged, refer to section 21.3.2.
[b] If any or all of the following codes are logged, 91/3, 91/4, 187/3, 100/3,
refer to section 91.2.
[c] If any codes except 91/3 are logged, refer to section 21.3.3.
21.3.2
Sensor Check
Perform the following steps to check the sensor.
1. Turn ignition OFF.
2. Unplug the TPS connector.
3. Turn ignition ON.
4. Read for active codes.
[a] If active code 91/3 and any other codes are logged, refer to section 21.3.7.
[b] If code 91/4 is logged, refer to section 21.3.3.
21.3.3
Return Circuit Check
Perform the following steps to check the return circuit.
1. Turn ignition OFF.
2. Install a jumper wire between pin A (return #952) and pin B (signal #417) of the TPS
harness connector.
3. Disconnect the vehicle harness connector at the ECM.
4. Measure resistance between sockets C3 and D2 on the vehicle harness connector. For
Throttle Position Sensor schematic, See figure 21-2.
[a] If the resistance measurement is less than or equal to 5 , refer to section 21.3.4.
All information subject to change without notice.
6SE497 9709 Copyright © 1997 DETROIT DIESEL CORPORATION
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