GS 20 Input Signals
GS 20 Input Signals
Power Supply and Grounds:
The GS 20 receives:
- KL 30 (constant battery power),
- KL 15 (terminal 15 of the ignition switch)
- KL 87 (operating power from the Engine Control Main Relay)
- KL 31 (ground connection for the control module electronics and peripheral component operation)
The GS 20 monitors the power/ground inputs for shorts (B+ and B-), open circuits and battery voltage levels (high and low).
Range Selector Switch:
The switch is mounted inside the transmission main case on the driver's side. This location provides precise monitoring of the Manual valve position and is sheltered from the harsh environment under the vehicle external of the main case. Adjustment is not required.
The range selector switch has 6 wires. The GS 20 provides the switch with 12 volts on one wire (pin 2 of connector X70004).
Depending on the range selector position, the switch provides coded high signals over five wires to the GS 20. The addition of the fifth wire (pin 1) is new compared with previous four wire range selectors providing a redundant P/N signal circuit.
Electronic Brake and Brake Test Switch:
The GS 20 monitors the brake pedal position to activate sport mode and for the shift lock operation. The control module receives both the brake and brake test hall effect sensor signals. When pressed;
- the brake light switch pulls a standing voltage in the GS 20 low,
- the brake test switch provides a high signal to a circuit monitor in the GS 20.
Kick Down Switch:
When the throttle pedal is pressed fully to the floor, the kick down switch closes providing a ground signal to the GS 20.
The GS 20 recognizes the ground as a request to provide an immediate down shift and to switch to the AGS sport mode shifting program.
Transmission Fluid Temperature Sensor:
Located in the transmission oil sump, the NTC oil temperature sensor's ohmic value decreases as the temperature increases. The GS 20 monitors the fluid temperature by sensing the voltage drop across the sensor causing a standing monitor voltage to "bleed" to ground. Rise and fall of the standing voltage value is a direct correlation of the fluid temperature.
Detection of high fluid temperature modifies the torque converter regulation control and modifies the shift program to aid in reducing transmission fluid temperature.
If the signal becomes impaired, the GS 20 applies a substitute temperature value based on Engine Temperature via CAN and stores a specific fault code.
Transmission Input and Output Speed Sensors:
The transmission speed sensors (turbine and output shaft) are analog inductive sensors that produce an AC sine wave similar to an ABS/ASC wheel speed sensor. The AC signal frequency is proportional to the rotation speed of the monitored components.
- The turbine speed sensor scans a pulse wheel attached to the forward clutch housing.
- The output shaft speed sensor scans a pulse wheel attached to the rear ring gear.
The GS 20 monitors these signals along with the engine speed signal (CAN) to calculate transmission slip ratio for plausibility and for the adaptive pressure control function.
The sensors are monitored for plausible signals, opens and shorts. Specific fault codes are stored for defects with these sensors.