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