Hummer H3. Manual — part 867

output shaft pass through the sensor's magnetic field. The AC voltage level and the number of
pulses increase as the speed of the vehicle increases. Output voltage varies with speed from a
minimum of 0.5 volts at 100 RPM to more than 100 volts at 8,000 RPM. The PCM/TCM
converts the pulsing voltage to vehicle speed. The PCM/TCM uses the vehicle speed signal to
determine shift timing and TCC scheduling.

Automatic Transmission Fluid Temperature Sensor

The automatic transmission fluid temperature (TFT) sensor is part of the automatic transmission
fluid pressure (TFP) manual valve position switch. The TFT sensor is a resistor or thermistor,
which changes value based on temperature. The sensor has a negative-temperature coefficient.
This means that as the temperature increases, the resistance decreases and as the temperature
decreases, the resistance increases.

The powertrain control module (PCM) or transmission control module (TCM) supplies a 5-volt
reference signal to the TFT sensor and measures the voltage drop in the circuit. When the
transmission fluid is cold, the sensor resistance is high and the PCM/TCM detects high signal
voltage. As the fluid temperature warms to a normal operating temperature, the resistance
becomes less and the signal voltage decreases. Refer to TRANSMISSION FLUID
TEMPERATURE SENSOR SPECIFICATIONS for a complete comparison of sensor
resistance, temperature and signal voltage.

The PCM/TCM uses the TFT sensor information to control shift quality and TCC application.

Transmission Range Switch

2007 Hummer H3

2007 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - H3

Fig. 484: View Of Transmission Range Switch
Courtesy of GENERAL MOTORS CORP.

The transmission range (TR) switch is part of the park/neutral position (PNP) and backup lamp
switch assembly, which is externally mounted on the transmission manual shaft. The TR switch
contains four internal switches that indicate the transmission gear range selector lever position.
The powertrain control module (PCM) or transmission control module (TCM) supplies ignition
voltage to each switch circuit. As the gear range selector lever is moved, the state of each switch
may change, causing the circuit to open or close. An open circuit or switch indicates a high
voltage signal. A closed circuit or switch indicates a low voltage signal. The PCM/TCM detects
the selected gear range by deciphering the combination of the voltage signals. The PCM/TCM
compares the actual voltage combination of the switch signals to a TR switch combination chart
stored in memory.

AUTOMATIC TRANSMISSION INLINE 20-WAY CONNECTOR DESCRIPTION

2007 Hummer H3

2007 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - H3

Fig. 485: Identifying Automatic Transmission In-Line 20-Way Connector
Courtesy of GENERAL MOTORS CORP.

The transmission electrical connector is an important part of the transmission operating system.
Any interference with the electrical connection can cause the transmission to set diagnostic
trouble codes or affect proper operation.

2007 Hummer H3

2007 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - H3

The following items can affect the electrical connection:

Bent pins in the connector from rough handling during connection and disconnection

Wires backing away from the pins or coming uncrimped, in either the internal or the
external wiring harness

Dirt contamination entering the connector when disconnected

Pins in the internal wiring connector backing out of the connector or pushed out of the
connector during reconnection

Transmission fluid leaking into the connector, wicking up into the external wiring harness
and degrading the wire insulation

Moisture intrusion in the connector

Low pin retention in the external connector from excessive connection and disconnection of
the wiring connector assembly

Pin corrosion from contamination

Damaged connector assembly

Remember the following points:

In order to remove the connector, squeeze the two tabs toward each other and pull straight
up without pulling by the wires.

Limit twisting or wiggling the connector during removal. Bent pins can occur.

Do not pry the connector off with a screwdriver or other tool.

Visually inspect the seals to ensure that they are not damaged during handling.

In order to reinstall the external wiring connector, first orient the pins by lining up the
arrows on each half of the connector. Push the connector straight down into the transmission
without twisting or angling the mating parts.

The connector should click into place with a positive feel and/or noise.

Whenever the transmission external wiring connector is disconnected from the internal
harness and the engine is operating, DTCs will set. Clear these DTCs after reconnecting the
external connector.

PARK - ENGINE RUNNING

With the gear selector lever in the PARK (P) position and the engine running, the line pressure
from the oil pump assembly is directed to various components in the valve body and the oil pump.

Pressure Regulator Valve

2007 Hummer H3

2007 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - H3