Originally Posted by need-a-vacation
I don't know of any of the trucks that have an electronic "dual ratio" rear end. Being 4wd both the rear and front diff would need to be a "dual ratio". I thought you may have meant you had a choice of either 3.73 or 4.11's.
The tow haul in most cases basically just changes the shift points of the trans.
Glad to hear you like the truck on the test drive!
Well our KNOWLEDGEABLE salesman was giving me BAD info and I apologize to you ALL for posting BAD info...here is the correct info on the TOW/HAUL Switch...
8. Tow/Haul Control
During tow/haul control, the ECM controls the engine output, transmission shift schedule and shift timing to ensure drivability when a trailer is towed. The tow/haul control includes a throttle control, shift schedule control, wide open throttle shift timing control and AI-SHIFT control.
** The conditions required for tow/haul control to operate are as follows:
- Shift position: D position (Tow/haul control does not operate in the S position).
- TOW/HAUL pattern select switch: ON
** The TOW/HAUL indicator light is used to inform the driver that tow/haul control is operating.
Throttle control changes the relationship between the accelerator pedal depression angle and the throttle valve opening angle.
** During tow/haul control, the throttle valve opening is increased by throttle control. As a result, acceleration performance is ensured.
Shift Schedule Control
The shift schedule control changes the upshift and downshift schedules during tow/haul control.
** For the upshift schedule, the upshift timing is changed to higher vehicle speeds, enhancing the use of lower gears. As a result, drivability is ensured.
** For the downshift schedule, the downshift timing is change to a wider throttle valve opening angle, enhancing the use of higher gears. As a result, the frequency of gear changes is reduced, allowing optimal shift quality.
Wide Open Throttle Shift Timing Control
Due to wide open throttle shift timing control, upshift timing is delayed to make use of high engine power when the accelerator pedal is fully opened.
** Wide open throttle shift control operates in 1st, 2nd and 3rd during tow/haul control.
11. AI (Artificial Intelligence)-SHIFT Control
In addition to shift pattern changes due to tow/haul control, AI-SHIFT control determines optimal transmission control based on input signals and automatically changes the shift pattern. As a result, a high caliber of transmission operation is achieved.
** The AI-SHIFT control includes a road condition support control and a driver’s intention support control.
** AI-SHIFT control is effect only with the shift lever in the D position, based on the accelerator and brake operation data. AI-SHIFT control will be canceled when the driver selects the S mode.
Road Condition Support Control
Under road condition support control, the ECM determines throttle valve opening angle and the vehicle speed whether the vehicle is being driven uphill or downhill.
1) When a trailer is not being towed:
** To achieve an optimal drive force while driving uphill, this control prevents the transmission from up-shifting to 4th, 5th or 6th gear.
** To achieve an optimal engine braking effect while driving downhill, this control automatically downshifts the transmission to 5th, 4th or 3rd gear.
2) When a trailer is being towed:
** To achieve an optimal drive force while driving uphill, this control prevents the transmission from up-shifting.
** To achieve an optimal engine braking effect while driving downhill, this control automatically downshifts the transmission.
** In addition to the shift pattern changes due to the road condition support control, the shift pattern is further changed when the tow/haul control is turned ON.
Driver’s Intention Support Control
1) When a trailer is not being towed Driver’s intention support control estimates the driver’s intention based on the accelerator operation and vehicle condition and selects a shift pattern that is well-suited to each driver.
2) When a trailer is being towed During tow/haul control operation, the driver’s intention support control ensures drivability while towing a trailer by determining the driver’s intention based on accelerator pedal operation and vehicle condition and performs the controls shown below:
Control= Sudden Accelerator Pedal Depress Control
Operation= When the driver operates (presses) the accelerator pedal quickly, this control causes the transmission to downshift rapidly to improve acceleration response.
Available for= 4th to 6th
Control= Sudden Accelerator Pedal Release Control
Operation= When the driver releases the accelerator quickly, this control makes it easy for the transmission to hold the gear, which improves engine braking force and re-acceleration response.
Available for= 3rd to 6th
Control= Sudden Deceleration Downshift Control
Operation= When the driver decelerates the vehicle suddenly, this control downshifts rapidly, which improves engine braking force and re-acceleration response.
Available for= 3rd to 6th
---2007 Tundra "New Car Features" document