The tilt/telescoping steering column is controlled by the steering column tilt/telescoping module (TTM). The TTM controls the movement of the two motors, one for the column tilt movement and one for the column telescoping movement. The motors operate independently of each other. Each motor has an attached position sensor.
Module Power/Ground
The rear junction block MEM T&T fuse supplies battery positive voltage (B+) via CKT 2840 (ORN) to power the steering column tilt/telescoping module (TTM). The rear junction block POWER T&T fuse supplies battery positive voltage (B+) via CKT 2940 (ORN) to the TTM. Ground for the TTM is provided via CKT 350 (BLK) to ground G200.
Motors
Both motors are reversible. For example, the tilt motor moves the column both up and down. When the TTM receives an input to move the column up, it supplies battery positive voltage (B+) and ground to run the motor to move the column up. When it receives a column down input, the TTM supplies power to the same motor, but the voltage and ground are on the opposite motor terminals. The voltage polarity is reversed and the motor runs the opposite direction, moving the column down.
Position Sensors
Position sensors are used by the TTM to store motor positions in memory and return the motors to the stored memory positions. The TTM provides a 5 volt reference voltage through CKT 9068 (BLU) and reference ground through CKT 9069 (YEL) to the tilt position sensor. The TTM provides a 5 volt reference voltage through CKT 961 (BLU) and reference ground through CKT 962 (YEL) to the telescoping position sensor. Each sensor is a potentiometer mounted to the corresponding motor. When the motor rotates, the resistance of the potentiometer varies and the TTM monitors the feedback voltage to determine the motor position. CKT 964 (ORN) is the tilt position input and CKT 963 (ORN) is the telescope position sensor input. The sensor feedback voltages vary from 0.25 volts to 4.75 volts. When an entry or exit position is saved, the TTM stores the motor positions by recording each position sensor feedback voltage. When an entry or exit position recall is commanded, the module moves the motors until all the position sensor feedback voltages equal the feedback voltages stored in memory.
Manual Movement
The steering column tilt/telescoping module (TTM) receives inputs from the tilt/telescope switch on CKT 954 (GRY), CKT 955 (YEL), CKT 952 (PNK), or CKT 953 (ORN) to move the column. Pressing the tilt/telescope switch sends an input to the TTM. When the TTM receives a valid input, it actuates the corresponding column motor.
Entry/Exit Personalization
The steering column tilt/telescoping module (TTM) stores personalization information, which enables and disables steering column entry positions and exit positions. The driver information center (DIC) is used to set and change personalization information. The instrument cluster in turn provides a Class 2 message to the TTM which specifies that the TTM enable or disable the entry and/or exit settings until again changed using the DIC.
Memory Set
The left hand front door module (LHFDM) receives the inputs from the memory function switch. The current steering column entry and exit positions may be recorded for two different drivers. To record the current positions, the SET MEMORY button is pressed, which is followed by a chime to acknowledge the input. Within 5 seconds, either the MEMORY-1 or MEMORY-2 button is pressed. When the LHFDM receives these inputs, it sends a Class 2 message to the TTM and the TTM records the feedback voltages from the column position sensors for the appropriate driver. A single chime is sounded to acknowledge that the position was recorded.
Memory Recall
When the MEMORY-1 or MEMORY-2 button is pressed, the LHFDM receives the input and a single chime is sounded. The LHFDM sends a Class 2 message to the TTM indicating which driver memory setting has been selected. The TTM applies battery positive voltage (B+) to the column motors until all the column position sensor feedback voltages equal the feedback voltages stored in memory for the appropriate driver.
Recall Personalization
When a keyless entry transmitter is used to unlock the vehicles doors, the remote function actuator (RFA) module communicates the unlock command and which driver performed the command to the steering column tilt/telescoping module (TTM) via a Class 2 message. There are three personalized recall options when the LHFDM receives an unlock message:
| • | Recall immediately upon receipt of the RFA message. |
| • | Recall when a key-in message is received. |
| • | Do not recall upon receipt of an RFA message. Recall functions are only performed with the memory switches. |
