ELECTRICAL SYSTEM CONTINUED
Speed Sensor (Transmission Output 1)
Speed Sensor (Transmission Output 2)
The two speed sensors for the transmission are located under the access cover (Figure 13, Item 1) that is on the
left side of the transmission. The access cover is under the left hand side differential output shaft.
These speed sensors are frequency sensors, which produce a signal that varies the frequency (Hz) as the
condition changes. The sensor generates a frequency by passing a metallic object such as the tooth of a gear in
front of the sensor. The ECM measures the frequency and determines the speed of the component. Each speed
sensor has two input connections to the ECM ("+" and "-").
The speed sensors provide inputs to the ECM that indicate the speed of the transmission and the speed of the
torque converter. The ECM will use this information to control the transmission. The ECM will use the input from
the two transmission speed sensors in order to determine which gear the transmission is in. The ECM will compare
the input speeds of the torque converter to the transmission speed to determine shifting points for the Autoshift
function. The ECM will compare the input speeds of the torque converter to the transmission speed to enable
The transmission speed sensors are used to diagnose each other during normal operation. The ECM periodically
checks and compares the value from each speed sensor. If the ECM determines that an abnormal condition exists
in one of the circuits, the ECM will log a diagnostic code for the involved component.
Figure 13. Speed Sensor Transmission Output 1 and 2.