Diagnostics – Class1 107490 - UNI-Governor 107396 107269 software v 6 00 User Manual

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C:\manuals\Uni-Gov-V6-107490

Class1 Uni-Governor Quick Tests

Operation description:

The governor is simply a Throttle Position Sensor (TPS) for the Engine Control Module (ECM). It sends
a varying voltage signal, or for Caterpillar Engines (CAT) a Pulse Width Modulated (PWM) signal to the
ECM at the remote throttle signal input. When operating in pressure (PSI) mode, the governor modu-
lates the output signal to maintain a specific input voltage from its pressure transducer. This voltage is
“set” into the governor’s memory by the use of the INC and DEC switches. A PRESET function is
available that causes the governor to attain either a specific pre-programmed voltage or pressure.
For Cummins, CAT and Navistar engines, once the ECM is programmed for remote throttle, the ECM
continuously looks for the signal. If it is not present, the ECM will record a fault and illuminate the CEL or
SEL dependent on the ECM. This is a quick check to see if a valid signal is present at the ECM. If there
is no Check Engine Light (CEL) or Stop Engine Light (SEL), then a valid signal from the governor is
present.

For most engines the remote throttle must be ‘turned on’ in the ECM to use the remote throttle signal.
For Cummins and CAT, this is performed by grounding a terminal at the ECM. Navistar ECM’s use
switched voltage.

The governor will not operate in any mode unless 12 VDC is applied at terminal 2 of the 12 pin connec-
tor (THROTTLE READY Interlock). This is evidenced by the illumination of the THROTTLE READY
LED. This will allow the governor to operate in RPM mode. 12 VDC applied to pin 10 of the 12 pin
connector (PUMP ENGAGED Interlock) illuminates the PUMP Engaged LED. If both the THROTTLE
READY and PUMP ENGAGED LED’s are lit, then the governor will illuminate the OKAY TO PUMP LED
and the governor will operate in either PRESSURE (PSI) or THROTTLE (RPM) mode.
note: The THROTTLE READY and PUMP ENGAGED LED’s will illuminate if the governor has a
ground and the inputs are active (12 VDC). This is not dependent on the governor functioning or even
having power applied. The OKAY TO PUMP LED is turned on by governor software and usually indi-
cates that the governor is operational.

Preliminary Diagnostic information:

To assist in governor diagnostics there is some preliminary information necessary. When power is first
applied to the governor, a set of characters is displayed. These are referred to as the ‘V’ number. On
governors produced after January 2001, if the IDLE switch is held when power is applied, the ‘V’ num-
ber will continue to be displayed until the IDLE switch is released. A typical number will look like the
following: V3.7b444. This contains the software version number, the engine type programmed into the
governor and the parameter settings.

The other information necessary is a brief but accurate description of the problem trying to be resolved.
What are you trying to correct? Provide a brief description of the operational anomaly.

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See page 3

for a diagnostic guide relating to this problem

Diagnostics