Usage:
3176 And 3406B (PEEC) Truck Engines
Reference: Service Manual Module, 3406B (PEEC) Truck Engine Test Procedures, SENR3479. Service Manual Module, Electronic Troubleshooting 3176 Diesel Truck Engine, SENR3913.
The throttle adjustment procedure is critical to insure proper engine performance. Some engines equipped with 9X9647 or 9X9648 Throttle Position Sensors (TPS) have experienced problems because the throttle linkage was not adjusted correctly. When incorrectly adjusted, the engine may experience low power, or in the worst case, "cutout" when fully loaded. Incorrect adjustment can cause the TPS rotary disk to travel beyond normal operating ranges. If the rotary disk travels too far (over rotates), the engine will "cutout" while fully loaded. If the rotary disk does not travel far enough (under rotates), full throttle will not be reached.
Incorrect adjustment cannot be detected with the Electronic Control Analyzer Programmer (ECAP) status display for throttle position. To verify correct TPS adjustment, connect the ECAP or Digital Diagnostic Tool (DDT) to the output of the TPS with the 8C9801 PWM Signal Adapter Group. Set the service tool to display the screen for duty cycle measurement of the pulse width modulated signal. Adjust the throttle linkage to get a low idle reading of 15 to 20% duty cycle and a high idle reading of 80 to 85% duty cycle. This adjustment may have to be performed several times before both low and high idle adjustment ranges are achieved at the same time.
For more details on the correct throttle adjustment procedure, see the Reference.