Usage:
The throttle position sensor may be one of two types. The "Remote-Mounted" (TPS) is about the size of a soft drink can and is connected to the throttle pedal by OEM-supplied linkage. It requires adjustment for proper operation. The "Pedal-Mounted" TPS is mounted directly to a specific style of throttle pedal and requires no adjustment and in fact can not be adjusted. Both sensors provide the same type of signal to the ECM.
The throttle linkages contain mechanical stops to prevent breakage of the rotating wheel on the front of the throttle position sensor. The low idle stop in the throttle linkages should be adjusted to allow little or no downward motion of the foot pedal before the engine rpm increases ("dead pedal" motion), and correct adjustment is necessary for the retarder enable to function correctly. Excessive "dead pedal" motion is undesirable.
With the 3406B (PEEC III) Engine, the maximum rpm obtainable is the selected rpm rating +20 rpm (300 bhp @ 1800 rpm rating would have a high idle rpm of 1820 even if the Top Engine Limit (TEL) is programmed to a lower value such as 1750 rpm).
With the 3406B (PEEC III) Engine, the high idle rpm in neutral is obtained before the throttle position sensor reaches its maximum signal. If the throttle linkage stop is set "by ear", the engine will not obtain full engine horsepower.
A (7X6400) Digital Diagnostic Tool (DDT) or (8T8697) Electronic Control Analyzer And Programmer (ECAP) must be used to adjust the full throttle linkage position mechanical stop (see Electronic Troubleshooting, 3406B (PEEC III) Diesel Truck Engine, Form No. SENR5147, or the Testing And Adjusting section of Systems Operation, Testing And Adjusting, Form No. SENR5146, for more information). Excessive motion past the full throttle position can cause damage to the throttle position sensor.