Transmission Control Systems: Description and Operation

Manual Trans. Lockout System:

MANUAL TRANSMISSION 1-4 UPSHIFT
The 1-4 upshift system has two major components:

- 2nd and 3rd gear blockout relay.
- 2nd and 3rd gear blockout solenoid.

The 2nd and 3rd gear blockout relay is mounted on the right front wheelhouse. The PCM uses engine speed, vehicle speed, throttle position and engine coolant temperature sensors to determine if the vehicle is within the parameters to shift directly to 4th gear while it is in 1st gear. The PCM provides a path to ground which energizes the relay when the vehicle should be shifted from 1st gear to 4th gear.

The 2nd and 3rd gear blockout solenoid is located on the transmission. When the 2nd and 3rd gear blockout relay is energized, it activates the 2nd and 3rd gear blockout solenoid which mechanically locks-out the transmission from being shifted into any other gear.

The 1-4 upshift system will be enabled if all of the following conditions are met:

- Engine running.
- Vehicle speed greater than 12 mph, but less than 19 mph.
- Throttle position less than 35%.
- Engine coolant temperature greater than 50°C (122°F).
- BARO greater than 76 kPa.

The 1-4 upshift (if all above criteria are met) will occur only once per upshift cycle. The 1-4 upshift system is not re-enabled unless vehicle speed drops below 1 mph.

ONE TO FOUR LIGHT
When the PCM enables the 1-4 upshift system, the PCM provides a ground which turns "ON" the one to four light. The one to four light will remain "ON" until the transmission is placed into 4th gear, vehicle speed is less than 12 mph or greater than 25 mph or the PCM disables the 1-4 upshift system.