COVER 2512272 - Caterpillar

Illustration 1 g00356995
(1) Secondary brake and parking brake pressure switch (2) Service brake and retarder pressure switch (3) Stop light pressure switch (4) Traction Control System pressure switch (5) Location of the secondary brake and parking brake pressure switch for EMS panel indicator on EMS equipped machinesSome input signals to the Electronic Programmable Transmission Control (EPTC II) during a shift can cause a hunting condition of the transmission. A hunting condition is a series of rapid, unwanted transmission upshifts and rapid, unwanted transmission downshifts. A hunting condition is caused by ground speed changes near a transmission shift point.The EPTC II is designed to prevent a hunting condition. After two seconds, the EPTC II will allow one shift back to the original gear.In normal operating conditions, a rapid shift may be necessary. An example of a normal operating condition is stopping the machine. If a rapid downshift is not made in this example, the engine will stop. When the secondary brake or the parking brake is used, the secondary brake and parking brake pressure switch (1) will signal the EPTC II that rapid shifts are necessary.When the secondary brake and parking brake pressure switch (1) is open, the ground to the EPTC II is removed. The EPTC II will then determine that a rapid shift is necessary. Whenever the secondary brakes or the parking brakes are engaged, the EPTC II will shift rapidly.When the secondary brake and parking brake pressure switch (1) is closed, a ground to the EPTC II is created. The EPTC II then allows one shift back to the previous gear.Note: Callout (5) shows the location of the secondary brake and parking brake pressure switch for the indicator light on the EMS panel. This switch is on EMS equipped machines. Machines that are equipped with the VIMS do not have this switch.