FILM-INST(RETARDING) 1239512 - Caterpillar

Illustration 1 g01106195
Open loop steering and speed control block diagram
An active left speed sensor diagnostic code or an active right speed sensor diagnostic code (CID 030 or CID 031) will cause the ECM to activate the "open loop" control mode. The ECM monitors the speed dial, the speed lever, the brake pedal, the steering wheel, the gear switch, the parking brake switch, the engine speed, and the harness code in order to determine the desired speed and turning radius. The ECM calculates how much current to send to each propel solenoid in order to approximately achieve the desired speed and turning radius. The ECM does not use feedback from the left speed sensor or from the right speed sensor in this mode. As a result, the ECM does not precisely control the propel speed or the steering radius. In the "open loop" mode, consistent steering and straight tracking are not guaranteed.Note: While in "open loop" mode, the ECM will monitor the speed sensor inputs in order to determine if there is an active diagnostic code present. When the diagnostic code is cleared, the propel diagnostic code lamp will turn off. The ECM will remain in "open loop" until the speed lever is moved to the NEUTRAL position.