Two Speed Rear Axle Circuit Description

Two Speed Rear Axle Circuit Description

Axle Circuit

The two-speed rear axle electric shift system consists of the following components:

* A two-speed rear axle shift switch
* A two-speed rear axle shift relay
* A two-speed rear axle shift relay

When the two-speed rear axle shift switch is closed (HIGH range), a ground is supplied from G101 or G111 (Automatic), or G401 (Manual) through the two-speed rear axle shift switch in the GRY/BLK (1467) circuit, to terminal 86 in the two-speed rear axle shift relay.

When the ignition switch is in the START or RUN position, voltage is supplied to the relay coil and relay switch contact from the AXLE circuit breaker in the BRN (241) circuit.

Electronic Shift

When the two-speed rear axle switch is in the LOW range, the Vehicle Speed Sensor Buffer receives a voltage signal at terminal A1 through the two-speed rear axle shift relay coil.

When the two-speed rear axle switch is placed in the HIGH range, a ground signal replaces the voltage at terminal A1. This condition changes the electronic calibration of the Vehicle Speed Sensor Buffer, maintaining an accurate vehicle speed output of the Vehicle Speed Sensor Buffer when the rear axle shifts to a higher gear ratio.

Air Shift

When the air-operated two-speed rear axle switch is shifted to the LOW range, the Vehicle Speed Sensor Buffer receives a voltage signal. At this point, no air pressure is flowing to the two-speed rear axle motor and the two-speed rear axle shift pressure switch.

When the two-speed rear axle switch is placed in the HIGH position, air is sent to the two-speed rear axle motor and the two-speed rear axle shift pressure switch.

The two-speed rear axle shift pressure switch opens when the two-speed rear axle shift pressure switch senses air pressure greater than 35 kPa (5 psi). This condition causes voltage to be removed from terminal A1 of the Vehicle Speed Sensor Buffer, which changes the electronic calibration of the Vehicle Speed Sensor Buffer. The output of the Vehicle Speed Sensor Buffer to the speedometer will now remain accurate with the higher gear ratio.