257b cat panel lights stay on and tail lights solenoid on…

ELECTRONICALLY CONTROLLED PILOT SYSTEM
The electronically controlled pilot system controls pilot oil flow to the drive system pilot
valves, the drive motor parking brakes, the work tool pilot valves, and the auxiliary control
valve spool in the control valve group.
The Operator Interlock Electronic Control Module (ECM) and the Auxiliary Hydraulic
Electronic Control Module (ECM) receive input signals from various switches. The control
modules process the input signals, make decisions, and provide corresponding output signals.
The Operator Interlock ECM provides output signals to the indicator lamp module, travel
solenoid, the parking brake solenoid, and the work tool solenoid.
The Auxiliary Hydraulic ECM provides output signals to the auxiliary hydraulic solenoids, and
the two-speed travel solenoid or the high flow solenoid. The Auxiliary Hydraulic ECM
communicates through the CAT Data Link and can be accessed with Cat Electronic Technician
(Cat ET).
The following three ON/OFF solenoids control the pilot oil flow:

Travel pilot solenoid: Directs pilot oil to the travel pilot valves and is located in the base of
the travel pilot valve group.
Parking brake solenoid: Directs pilot oil to release the drive motor parking brakes and is
located in a manifold block on the left rail of the machine.
Work tool pilot solenoid: Directs pilot oil to the work tool pilot valves and is located in the
base of the work tool pilot valve group.
The following solenoids are proportional solenoids that control pilot oil flow to the auxiliary
hydraulic control spool.
Auxiliary solenoid "A1": Directs pilot oil to the auxiliary control valve spool in the control
valve group.
Auxiliary solenoid "A2": Directs pilot oil to the auxiliary control valve spool in the control
valve group.
NOTE: The auxiliary solenoids are proportional solenoids; however, they may function
as ON/OFF solenoids. The function of the auxiliary solenoids is determined by the
configuration of the Auxiliary Hydraulic ECM.
The Auxiliary Hydraulic ECM also controls the solenoids for the two-speed travel and
high flow options. The operation of those solenoid will be discussed with their
respective systems

click below

The "B" Series Skid Steer Loaders and Multi-Terrain Loaders are equipped with two ECMs as
standard equipment. The ECMs on the Skid Steer Loaders are mounted to the inside of the
frame at the front of the machine. The ECMs on the Multi-Terrain Loaders are mounted on the
frame at the front of the machine or they are mounted to the skid plate of the frame at the front
of the machine. The Operator Interlock ECM (1) prevents engine starting, machine travel, and
work tool operation until certain conditions are met. The Auxiliary Hydraulic ECM (2)
controls the auxiliary hydraulic circuit, the optional two-speed travel system, and the high flow
auxiliary hydraulic system.
The ECMs can be accessed from below the machine by removing the access plate (3) or by
removing the floorplate in the bottom of the operator’s compartment.
A third ECM is installed on machines equipped with the optional Machine Security System
(MSS). This ECM is installed on the rear of the operator’s compartment in the place of the
former Interlock ECM.

The Operator Interlock ECM disables the travel solenoid and park brake solenoid until the
operator is seated with the armrest down and the momentary park brake switch is depressed.
The travel solenoid allows pilot oil to flow to the speed and direction control lever when
energized. The park brake is released by the pilot oil flowing from the park brake solenoid
when the solenoid is energized. The park brake indicator lamp is illuminated whenever the
parking brake solenoid is de-energized.
The travel solenoid and park brake solenoid are de-energized when the park brake switch is
actuated a second time. The solenoids are also de-energized whenever the armrest or seat
switches are opened or a failure within the system.

The Operator Interlock ECM disables the work tool hydraulic system until the operator is
seated with the armrest down, the door closed, the hydraulic lockout switch off, and the park
brake released.
The work tool pilot and travel solenoids are energized, along with the detent coil, by the
Operator Interlock ECM when the park brake switch is depressed. Once energized, the work
tool pilot solenoid and the detent coil will not be disabled with the park brake switch.
The work tool hydraulic system can be disabled independently of the travel system by
depressing the optional hydraulic lockout switch or by opening the operator's compartment
door. The work tool pilot solenoid and the detent coil remain energized as long as the
hydraulic lockout switch and the door switch remain closed to ground. Opening either of the
switches causes the ECM to disable the solenoids. The work tool pilot and detent solenoids are
re-energized when both of the switches are closed to ground.

The Operator Interlock ECM monitors the solenoids and switches for opens, shorts to ground,
and shorts to battery. The ECM will then flash the armrest indicator and/or the park brake
indicator to indicate a problem.
Open circuits and shorts to ground prevent the travel solenoid from energizing, disabling the
travel system, and applying the parking brake. The ECM will cause the park brake indicator
lamp to flash to signal the operator of the problem. Shorts to battery have different effects
depending on the state of system when the fault occurred. If the travel solenoid is commanded
OFF when the short to battery occurred, the ECM will open the return line and the travel
system is disabled. The ECM will cause the park brake indicator lamp to flash to signal the
operator of the problem. If the travel solenoid is requested ON when the short to battery
occurs, then the system operates normally.

Open circuits and shorts to ground cause the park brake to be applied. Because the ECM has
no indication that the park brake was applied, it may be possible to drive through the park
brake, as the transmission remains active. Shorts to battery result in the park brake solenoid
being continuously on (brakes released). Because the park brake is spring-applied, the park
brake is applied when the machine is electrically turned off.
The Operator Interlock ECM monitors the park brake switch for shorts to ground or failed
closed conditions. The ECM determines this condition by detecting the signal from the park
brake switch being grounded for greater than 30 seconds. The Operator Interlock ECM causes
the park brake indicator lamp to flash to signal the operator of the system problem. The
indicator lamp flashes immediately if the park brake switch is closed to ground on power-up.
If the Operator Interlock ECM detects both inputs for the seat switch and the armrest switch
grounded, the armrest/seat switch indicator lamp will flash to indicate a problem. The machine
will start with both inputs closed; however, the travel and work tool systems will be disabled.
Additionally, if the ECM detects both inputs are open for more than 5 seconds, the armrest/seat
switch indicator lamp will flash and the travel and work tool systems will be disabled.
The Operator Interlock ECM monitors the park brake switch for shorts to ground or failed
closed conditions. The ECM determines this condition by detecting the signal from the park
brake switch being low for greater than 30 seconds. The Operator Interlock ECM causes the
park brake indicator lamp to flash to signal the operator of the system problem. The indicator
lamp flashes immediately if the park brake switch is closed to ground on power-up.
The Operator Interlock ECM monitors the work tool pilot solenoid and detent coil for open
circuits, shorts to battery, and shorts to ground. The ECM cannot distinguish between the work
tool pilot solenoid and detent coil because they are wired in parallel. Open circuits and shorts
to ground will prevent the coils from energizing. Shorts to battery has different effects
depending on the state of the system when the fault occurred. If the solenoids are requested
OFF with a short to battery, the ECM will open the return line, resulting in the disabling of the
work tool and travel systems and the engagement of the parking brake. The armrest/seat switch
indicator lamp flashes to signal the operator of the problem. If the solenoids are requested on,
the work tool hydraulic system functions normally.
A failure of the hydraulic lockout switch or the cab door switch in the open position prevents
the switch from enabling the work tool hydraulic system. The work tool hydraulic system
remains inactive, regardless of the switch position. This condition may be indicated by the
lockout indicator lamp remaining on.

Check for those things first and if you decide for the diagrams and troubleshooting lee know once accepted so I know to post the link on my next login.

Pleasure to help

Hi Rob, Sent to your e mail. Let me know once you have them.

Pleasure to help Rob.