TRANSFER CONTROL
The transfer hydraulic pressure control unit includes a valve body attached to the side of the extension case through a gasket and separator plate.
The pressurized fluids for the transfer hydraulic pressure control (line pressure and pilot pressure) are supplied from the oil pump by way of the passages formed in the transmission case and then the passages in the extension case that lead to the hydraulic circuit in the transfer valve body.
The line pressure is regulated by the transfer control valve whose opening is controlled by the transfer pressure created by the transfer duty solenoid.
Scheme 89
- The transfer duty solenoid is controlled by the TCM. The TCM changes the solenoid controlling duty ratio according to the driving conditions.
- The transfer duty solenoid creates the transfer pressure from the pilot pressure. The transfer pressure is applied to the transfer control valve and adjusts the valve's opening.
- The line pressure directly led to the transfer control valve, on the other hand, is regulated by the transfer control valve and becomes the transfer clutch pressure.
- The transfer clutch pressure is applied to the transfer clutch and engages the clutch to a controlled degree. In this way, the degree of transfer clutch engagement is varied so that optimum torque is distributed to the rear wheels according to vehicle driving conditions.
The on-board diagnostics system detects and stores in the form of a code a fault that has occurred in any of the following input and output signal systems.
| Rear vehicle speed sensor | Transfer duty solenoid | Low clutch timing solenoid |
|---|---|---|
| Front vehicle speed sensor | ATF temperature sensor | Torque converter turbine speed sensor |
| Throttle position sensor | Engine speed signal circuit | |
| Shift solenoid 1 | Line pressure duty solenoid | |
| Shift solenoid 2 | AT load signal circuit | |
| 2-4 brake timing solenoid | Torque control signal circuit | |
| Lock-up duty solenoid | 2-4 brake duty solenoid |
ON BOARD DIAGNOSTICS SYSTEMS
If a fault has been detected, the system tells the fault by causing the AT OIL TEMP warning light to operate as follows
- Repeated flashing at 4 Hz frequency ...Errors such as battery trouble
- Repeated flashing at 2 Hz frequency ...No faults in the system
- Flashing at different intervals and frequencies ...Diagnostic trouble codes of corresponding faults
- Continued illumination of light ...Fault in inhibitor switch, idle switch, or wiring