I have a 1990 Toyota Dually VZN-95L with a 10 foot van body w/overhead door, I purchased from Penske Truck rentals in 1993. I realize I'm a few years late in this discussion, but I have over 270,000 miles and over 30 years behind the wheel of this truck. I'm a locksmith (lots of brass and steel), so my poor little 1-Ton truck is grossing over 8,000 lbs. I've beefed up both the front and rear suspensions, and there are some hills where my maximum speed is 15mph floored. Because of the weight, my gas mileage dropped from about 12mpg (empty) to about 8. I go through tires, calipers and shoes every 10,000 miles, and rotors and drums every 20,000, being resurfaced at 10k. I have PLENTY of miles on this truck running at it's maximum capability. I wore out, and replaced the engine with a rebuilt at about 240K, and rebuilt the worn out transmission at about 260k. Here's my experience with the ETC transmission and Over Drive. These speeds are all approximate as I'm generally not focused on them, and some stuff I still haven't figured out.
Regardless of the ETC setting, flooring it is designed take the engine to it's maximum RPM (horsepower); somewhere around 30mph in 1st and around 55mph in second. I've never topped it out in 3rd, I stay within the speed limits. Over-Drive is just a 4th gear designed to save RPMs (and gas). Once I got the down-shift cable adjusted correctly, it would automatically shift back into 3rd on a slight upgrade. I only use OD on the highway because when you touch the brakes in OD the engine RPMs slow down. I'm pretty sure it's not "freewheeling" or shifted into neutral, because the RPMs don't drop that much. My guess is that the Lock-Up Torque Converter releases. At any rate, whatever it does, it loses engine breaking, and at 8,000lbs, I want all the engine breaking I can get! I ALWAYS take it out of Over-Drive when slowing on the highway, and ALWAYS down shift when slowing on a hill. The transmission will NOT downshift into an over-rev condition. If you pull the lever into "L" at 70mph, it'll go into 2nd at about 60, and 1st at about 35.
The "ECT" switch ONLY effects mid-throttle stuff. I always drive in the power mode and my normal up shift speeds are 1st to 2nd between 19 to 24mph, and 2nd to 3rd between 30 to 45mph. I have experimented with the "Normal" mode a few times (out of curiosity), and it seems like everything happens about 5 to 10 mph earlier (slower). It all depends on throttle position.
I just started having early shifting problems with my transmission. Sometimes from a stop sign, it will shift 1st, 2nd, 3rd, 4th, and lockup the torque converter, before it hits 15mph. I had the ECU next to the passengers right foot rebuilt, but everything is still virtually the same. Does anyone know what tells this transmission how fast the vehicle is going?
Rare