I have an Eaton transfer switch with an ATC-300 controller. The Plant Exerciser is programmed to run once a week on Monday with load transfer and that is working just fine. But also on Friday the generator will kick on without load transfer and I can't find a program in the Plant Exerciser that would cause this. I need it to stop running on Friday.

Which transfer case does it have ????

Is the service light on ?
SERVICE indicator (4WD/AWD) Lamp
The SERVICE indicator (4WD/AWD) lamp is an integral part of the cluster and cannot be serviced separately. This lamp is used to inform the driver of the vehicle of malfunctions within the automatic transfer case (ATC) system. The SERVICE indicator (4WD/AWD) lamp is controlled by the transfer case shift control module via CKT 1567.
Circuit Description
The ignition switch supplies Ignition 3 voltage to the transfer case shift control module at connector C1 terminal E10 using the 4WD Fuse. When the ignition switch is first turned to the RUN position, the transfer case shift control module responds by flashing the SERVICE indicator (AWD/4WD) lamp for approximately 2 seconds, then turning it OFF, while performing tests on the ATC system. The transfer case shift control module will continue to perform tests on the ATC system during a normal drive cycle.

Hooking up a factory or some other professional scan tool that can view DTC'S - diagnostic trouble code's in the 4X4 control module would be the best way to find the problem.

DTC B0768 Service Indicator Circuit High
DTC B2725 ATC Mode Switch Circuit Malfunction
DTC C0300 Rear Speed Sensor Malfunction
DTC C0305 Front Speed Sensor Malfunction
DTC C0308 Motor A/B Circuit Low
DTC C0309 Motor A/B Circuit High
DTC C0310 Motor A/B Circuit Open
DTC C0315 Motor Ground Circuit Open
DTC C0323 T-Case Lock Circuit Low
DTC C0324 T-Case Lock Circuit High
DTC C0327 Encoder Circuit Malfunction
DTC C0357 Park Switch Circuit High
DTC C0362 4LO Discrete Output Circuit High
DTC C0367 Front Axle Control Circuit High
DTC C0374 General System Malfunction
DTC C0376 Front/Rear Shaft Speed Mismatch
DTC C0387 Unable to Perform Shift

Are there any faults listed on the control display? If display is dark then likely a battery issue. Check battery voltage with a Digital Multi Meter (DMM). It should be at least 12.5VDC.

you may have a bad switch ! i could tell you how to test it ,but could be fairly lengthy . do you own a volt meter ? do you know how to use one? should also check for dtc's in transfer case control module !
transfer case shift control switch indicator inoperative - one or more
the indicator lamps circuit consist of 5 individual lamps contained inside the mode/range switch assembly. the following lamps are contained inside the respective range button:
?€¢
auto 4wd

?€¢
2hi

?€¢
4hi

?€¢
4lo

each time the ignition is cycled, all 5 mode indicators light simultaneously, as an indicator check to ensure proper operation of the indicators. when the ignition is on, the transfer case shift control module illuminates the indicator lamp that corresponds to the current atc gear position, by providing a ground through a current limiting driver.
the transfer case shift control module flashes each indicator lamp after a shift has been requested and continues to flash until the transfer case shift control module completes the shift.
a solid state circuit, located inside the switch, supplies ignition voltage to the lamps. the solid state circuit also receives voltage when the headlamp switch is in the parklamp or headlamp position. when the solid state circuit receives voltage from the headlamp switch, the circuit reduces the voltage that is supplied to the indicator lamps, dimming the lamps when the headlamps are on.
test description
the numbers below refer to the step numbers on the diagnostic table.

1. this step tests the transfer case electrical control of the lamp circuits.


2. this step helps determine module failures.


3. this step tests the affected lamp circuit for an open or high resistance.


4. this step tests the lamp feed circuit for an open or short to ground.

these diagnostic procedures will help you to find and repair automatic transfer case (atc) system malfunctions. this service category also contains information for repairing atc system malfunctions. for best results, use the diagnostic tables and follow the sequence listed below:

1. perform the diagnostic system check - transfer case. all atc diagnostics must begin with the diagnostic system check - transfer case. the diagnostic system check - transfer case determines the following:
?€¢
proper service 4wd indicator operation



?€¢
ability of the transfer case shift control module to communicate through the data link connector (dlc)



?€¢
existence of atc dtcs


2. refer to the diagnostic table as directed by the diagnostic system check - transfer case. the diagnostic tables help enable you to diagnose any atc system malfunction. bypassing these procedures may result in the following:
?€¢
extended diagnostic time



?€¢
incorrect diagnosis



?€¢
incorrect parts replacement


3. repeat the diagnostic system check - transfer case after you perform any repair or diagnostic procedure. this will verify that you correctly performed the repair. this will also ensure that other malfunctions do not exist.

Check with an Eaton power service center. Their sensors/relays are notoriously complicated.

It is most likely set to exercise once a week and run for about 1/2 hour or so

Did it always do this? Is there a factory 'exercise' (non-load) built into the transfer assembly?

http://www.homegeneratorsystems.com/service_support/manuals/index.cfm?rd=1

This link will take you to their site where you can download their manual.

Setting Exercise Timer
The Home Standby Generator is equipped with an exercise
timer that will start and exercise the system once every
seven days. During this exercise period, the unit runs for
approximately 20 minutes and then shuts down. Electrical
load transfer DOES NOT occur during the exercise cycle
(unless an utility power outage occurs).
A switch on the control panel is labeled “Set Exercise”
(depicted on page 10).The specific day and the specific time
of day this switch is pressed is programmed into the
control board memory.This date and time is then used to
automatically initiate the system exercise cycle.
To perform the Set Exercise procedure:
1. Choose the day and time you want your Home
Standby Generator to exercise.
2. On that day and time, set the AUTO/OFF/MANUAL
switch to OFF.
3. Press and hold down the “Set Exercise” switch for two
seconds.
4. Set the AUTO/OFF/MANUAL switch to AUTO.“Set
Exercise” is complete.
For example, if you press the “Set Exercise” switch on
Sunday morning at 10:00 AM, the unit will run an exercise
cycle the following Sunday at 10:00 AM (+/- 1/2 hour).
NOTE: “Set Exercise” will only work if the unit is in the
Automatic mode and this exact procedure is followed.The
exerciser does not need to be re-set if the 15 Amp fuse is
removed or changed.The exerciser will need to be re-set if
the 12 Volt DC battery is disconnected.
If you want to change the day and time the unit exercises,
simply perform the “Set Exercise” procedure at the exact
weekday and time you want it to take place.
• To prevent possible injury that might be caused by such sudden
starts, always set the AUTO/OFF/MANUAL switch to OFF.
• Remove the 15 Amp fuse before working on or around the
generator or transfer switch.

You definitely want to follow the manual procedure to avoid a possible load loss:

http://powerquality.eaton.com/Products-services/Backup-Power-UPS/9390.aspx?cx=3

9.1.4 Transfer from Normal to Bypass Mode
To transfer the critical load to Bypass mode:
C A U T I O N
In Bypass mode, the critical load is not protected from commercial power interruptions and abnormalities.
1. Press the CONTROLS pushbutton on the main menu bar. The System Controls
screen appears.
2. Press the BYPASS pushbutton on the System Controls menu bar.
The UPS transfers to Bypass mode and the critical load is immediately supplied
by the bypass source. If the bypass source is not available, the power processor
remains on and an alarm sounds.
3. The UPS is now operating in Bypass mode and the BYPASS status indicator is
illuminated.
The power module (PM) status indicates READY. The system is now on bypass
and the UPS power processor remains on.


At this point, you can operate an external bypass switch to get to maintenance bypass if needed.

1999 chevy 2500 ??? Come on a warranty , get real . Did you have the 4X4 system checked for DTC'S - diagnostic trouble code's ? Can set a few .
DTC B2725 ATC Mode Switch Circuit Malfunction
DTC C0300 Rear Speed Sensor Malfunction
DTC C0305 Front Speed Sensor Malfunction
DTC C0308 Motor A/B Circuit Low
DTC C0309 Motor A/B Circuit High
DTC C0310 Motor A/B Circuit Open
DTC C0315 Motor Ground Circuit Open
DTC C0323 T-Case Lock Circuit Low
DTC C0324 T-Case Lock Circuit High
DTC C0327 Encoder Circuit Malfunction
DTC C0367 Front Axle Control Circuit High
DTC C0374 General System Malfunction
DTC C0376 Front/Rear Shaft Speed Mismatch
DTC C0387 Unable to Perform Shift
DTC C0550 ECU Malfunction
DTC C0611 VIN Information Error

The range/mode switch circuit consists of four normally open switches. The automatic transfer case control module supplies a regulated 8 volt DC to the switch through circuit 431. The switch has circuit 1693 to return current to the automatic transfer case control module through a 9.09K ohms resistor located inside the switch.
The transfer case shift control module constantly monitors this signal voltage to determine the condition of the mode switch circuit. If no buttons are pressed, and the transfer case shift control module detects a voltage level outside the possible range (approx.-0.5 to 1.0 volts) for longer than 5 minutes, the transfer case shift control module will set this DTC or if a button is held down or sticks for a period longer than 5 minutes.
When each of the switches is depressed they will complete a circuit through their own specific resistor. The transfer case shift control module continuously monitors the switch input to determine whether the 4HI, AUTO 4WD, 2HI, and 4LO button selections are made by the driver. Neutral may be obtained if the following conditions are met:
• The engine is running.
• The automatic transmission is in neutral (or the clutch pedal is depressed on a manual transmission application).
• The vehicle speed is below 3 MPH.
• The transfer case is in the 2HI mode.
Once these conditions have been met, pressing and holding both the 2HI and 4LO buttons for 10 seconds will shift the transfer case into neutral, turning on the red neutral indicator lamp.
If you are not familiar with these electronic systems ,I suggest you take your vehicle to a qualified repair center .

if the s2 and load are flashing every couple of seconds that means your exerciser is set.