A/T - A500, A518 No Fourth Gear: Overview
Date: 1996Technical Bulletin # 357
^ Transmission:
A500/A518
^ Subject:
No 4th gear
^ Application:
Dodge
A500/A518
No Fourth Gear
Fourth gear is electronically controlled on the A500/A518. In order for the PCM to allow fourth gear, the engine temperature must be more than 65°F, the overdrive switch/module must be on, the VSS must indicate at least 25 MPH, and the TPS must indicate above an idle and less than 70 percent open. When all conditions are met, the overdrive solenoid will be energized for fourth gear.
Depending on the engine application, one of four types of systems may be used. Use the following descriptions to identify which type the vehicle has.
TYPE I MODULE:
This module may be part of the overdrive cancel switch and is mounted on the steering column or near the glove compartment. The overdrive control module will not allow overdrive until the signal to allow fourth gear is sent by the PCM (the overdrive cancel switch must be in the on position (figure 1).
TYPE II MODULE:
This module signals the PCM when the overdrive cancel module switch is on; thus preventing fourth gear (figure 2a). Some overdrive cancel modules also monitor transmission oil temperature and prevent fourth gear if the transmission oil temperature exceeds 27O°F (figure 2b).
TYPE III MODULE:
This type of module has a switch and indicator bulb only. When the overdrive cancel button is pushed, the PCM receives this signal and cancels fourth gear (figure 3).
1992 DAKOTA MODULE:
This module works like a type III module and also includes an oil temperature sensor. If the transmission oil temperature exceeds 270°F, the overdrive cancel module signals the PCM to cancel lockup and fourth gear.
The transmission oil temperature light will also come on when this occurs (figure 4).