Beginning at the start of production for the model year 2005, Dodge trucks equipped with the 5.9 diesel and 48RE transmission, were equipped with an electronically controlled Transmission Throttle Valve Actuator (TTVA). This Actuator has replaced the previous Throttle Valve Cable, which controls the Throttle Valve in the Valve Body.
To electronically control of the Throttle Valve inside the valve body
1. TRANSMISSION THROTTLE VALVE ACTUATOR - The TTVA consists of an electronic DC motor, which has two potentiometers and a gear driven system that controls the Throttle Valve in the valve body, for shift timing, passing gear below 4th gear and pressure control. The position of the geartrain is monitored by the TTVA Position sensor which supplies an input to the Engine Control Module. The TTVA is controlled by the ECM thru the inputs of Accelerator Position Sensor 1 and 2. Note: If the TTVA is removed from the transmission, the ECM will have to relearn its "0" position. The ignition will have to be turned on and the engine off for 30 seconds to accomplish "Auto Zero."
With the addition of the TTVA a new wiring harness was introduced. Refer to Figure 4 for a partial wire schematic of the TTVA and its connectors.
2. TRANSMISSION CASE - The transmission case had two bosses added to it to mount the new TTVA.
The previous design Transmission Case is not interchangeable with the new design TTVA because of the lack of mounting bosses on the case.
TTVA TROUBLE CODE DESCRIPTIONS
P1749 - TTVA Position Sensor Low (Electrical)
P1750 - TTVA Position Sensor High (Electrical)
P1751 - TTVA Position Minimum range Performance (Mechanical)
P1753 - TTVA Position Mechanical Performance (Mechanical)
P1754 - TTV Actuator Stuck (Electronic/Mechanical)
P1755 - TTVA Control Circuit (Electronic/Mechanical)
Note: Some of the DTC's listed can cause the voltage to the TTVA to be shut off by the ECM, this will in turn cause the motor position to be in high TV mode.
Note: TTVA motor control and TTVA position sensor voltages are subject to change. The ECM will re-calibrate its current "0" position when the ignition is turned on and the engine is not running for 30 seconds.
Subscribe to Motor Age and receive articles like this every month…absolutely free. Click here