Hummer H2. Manual — part 2381

volts at 100 RPM to more than 100 volts at 8,000 RPM. The PCM converts the pulsing voltage to vehicle speed.
The PCM 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 PCM 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 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 TFT Sensor Specifications for a complete comparison of sensor resistance,
temperature and signal voltage.

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

Transmission Range Switch

Fig. 495: Transmission Range Switch (M30/M32)
Courtesy of GENERAL MOTORS CORP.

2004 Hummer H2

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E (Introduction) - Hummer H2

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)
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 detects the selected gear range by
deciphering the combination of the voltage signals. The PCM compares the actual voltage combination of the
switch signals to a TR switch combination chart stored in memory.

Tow/Haul Mode Switch

2004 Hummer H2

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E (Introduction) - Hummer H2

Fig. 496: Tow/Haul Mode Switch
Courtesy of GENERAL MOTORS CORP.

Tow/Haul mode enables the operator to achieve enhanced shift performance when towing or hauling a load.
When tow/haul mode is selected, the tow/haul switch input signal to the body control module (BCM) is
momentarily toggled to zero volts. This signals the powertrain control module (PCM) to extend the length of
time between upshifts and increase transmission line pressure. Cycling the tow/haul switch again disables
tow/haul mode and returns the transmission to a normal shift pattern.

AUTOMATIC TRANSMISSION INLINE 20-WAY CONNECTOR DESCRIPTION

2004 Hummer H2

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E (Introduction) - Hummer H2

Fig. 497: Automatic Transmission Inline 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.

2004 Hummer H2

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E (Introduction) - Hummer H2