1 - 4 Upshift Control (Manual Transmission Only)

Six Speed Transmission:

DESCRIPTION
The 1-4 upshift system used with the 6 speed manual transmission is used to improve fuel economy under certain road load conditions.

OPERATION
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 located on the right wheel housing in the engine compartment. The ECM use engine speed, and vehicle speed to determine if the vehicle is i 1st or 4th gear. The ECM provides a path to ground which energizes the relay when the vehicle should be shifted from 1 gear to 4th gear.

The 2nd and 3rd gear blockout solenoid is located in the transmission linkage. 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 than 4th gear, from 1st gear.
The 1-4 upshift system will only be active on the first shifting sequence. Vehicle speed must go below 1 mph before the 1 to 4 upshift system will reset.

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

- Engine speed greater than 1,200 RPM.
- Throttle position less than 30%.
- Engine coolant temperature greater than 45°C (113°F).
- Transmission in first gear.
- Vehicle speed greater than 12 mph but less than 19 mph.

COMPONENTS

Vehicle Speed Sensor
The ECM uses engine speed divided by vehicle speed to determine the gear selected in the manual transmission. The ECM receives vehicle speed input from the Vehicle Speed Sensor (VSS).

The Vehicle Speed Sensor (VSS) is a small Permanent Magnet (PM) generator mounted in the transmission. It uses a gear, driven by the transmission, to generate voltage pulses at a rate of 4000 pulses per mile. The ECM then sends this signal to the Central Control Module (CCM), cruise control module and radio tuner control head.

One to Four Light
Whenever the ECM enables the 1-4 upshift system, the ECM provides a ground to turn "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 12mph or greater than 19 mph, or the ECM disables the 1-4 upshift system.