K 1500 Suburban 4WD V8-5.3L VIN Z Flex Fuel (2003)
Fluid Pressure Sensor/Switch: Description and Operation
4L60-E/4L65-E
4L60-E/4L65-E
Transmission Fluid Pressure (TFP) Manual Valve Position Switch
Important: Seven valid combinations and two invalid combinations are available from the TFP manual valve position switch. Refer to the
Transmission fluid Pressure (TFP) Manual Valve Position Switch Logic table for valid/invalid combinations for range signal circuits A, B
and C.
The transmission fluid pressure (TFP) manual valve position switch consists of five pressure switches (two normally-closed and three normally-open) on
the control valve body that sense whether fluid pressure is present in five different valve body passages. The combination of switches that are open and
closed is used by the PCM in order to determine the actual manual valve position. The TFP manual valve position switch, however, cannot distinguish
between PARK and NEUTRAL because the monitored valve body pressures are identical in both cases.
The switches are wired to provide three signal lines that are monitored by the PCM. These signals are used to help control line pressure, torque converter
clutch apply and shift solenoid valve operation. Voltage at each of the signal lines is either zero or twelve volts.
In order to monitor the TFP manual valve position switch operation, the PCM compares the actual voltage combination of the switches to a TFP
combination table stored in its memory.
The TFP manual valve position switch signal voltage can be measured from each pin-to-ground and compared to the combination table. On the
automatic transmission (AT) wiring harness assembly, pin N is signal A, pin R is signal B. and pin P is signal C. With the AT wiring harness assembly
connected and the engine running, a voltage measurement of these three lines will indicate a high reading (near 12 volts) when a circuit is open, and a
low reading (zero volts) when the circuit is switched to ground.
The transmission fluid temperature (TFT) sensor is part of the TFP manual valve position switch assembly.
