I have a 2016 GX460. Where is the Tow/Haul mode button? Can I add one? I believe I need more control over the torque converter's Lock/Unlock feature in the transmission. The "S" position may suffice as an alternative - forcing the vehicle not to upshift past gear X. Any help would be appreciated.
Back story:
I towed my 4000lb trailer for the first time with the gx460 over the weekend. I do not see a Tow/Haul button on the vehicle anywhere. Looking here: https://lexusgxor.com/_media/general:a760f.pdf (page1/47 or pg108) it suggests such a mode should exist. ..."A tow/haul control is used on the models with towing package. This controls the engine throttle, transmission shift schedule and shift timing to ensure driveability when a trailer is being towed." My experience from the weekend trip was;
1) Vehicle constantly hunted for gears while on the highway from speeds around 50-75mph. Eventually the computer found its way into 4th gear and sorta kinda stayed there but only after me fiddling around with my speed to keep it from shifting all over the place. Eventually I moved the shifter over to "S" position and forced it to 4th.
2) Transmission temps were ludicrously high (yep, I'm aware of the transmission cooler mod, it's on my list). With a 195F coolant temp, I saw 215F on a flat and level cruise, long hill pulls reaching 235F in the pan and as high as 250 in the TC.
3) The A760F 6-speed transmission is 6 speeds. But there were distinctly "more gears" than that. 4th had two different rpms about 300-500 rpm apart, same with 5th, etc. Like there was an over/under drive in there. A less appealing alternative is that when 4th/5th gear "unlocked" there was that much slippage through converter (which seems more likely considering the "ludicrous" temps reported in item2 above). Any ideas here?
4) I got about 10mpg towing. for reference, I easily achieve 19-20mpg round town 20-22mpg highway on when not towing. But when towing, the slightest headwind or grade forced me back to 4th gear which put my rpms up to about 2600-3000. My other tow vehicle for this camper has been a 5.9 Cummins which was a cake walk by comparison (dugh of course). Anyways, i expect that if i can keep the gx460's transmission locked it would behave much better, lower the transmission temps, and get another mpg or two. Hence the question up top.
thanks,
Back story:
I towed my 4000lb trailer for the first time with the gx460 over the weekend. I do not see a Tow/Haul button on the vehicle anywhere. Looking here: https://lexusgxor.com/_media/general:a760f.pdf (page1/47 or pg108) it suggests such a mode should exist. ..."A tow/haul control is used on the models with towing package. This controls the engine throttle, transmission shift schedule and shift timing to ensure driveability when a trailer is being towed." My experience from the weekend trip was;
1) Vehicle constantly hunted for gears while on the highway from speeds around 50-75mph. Eventually the computer found its way into 4th gear and sorta kinda stayed there but only after me fiddling around with my speed to keep it from shifting all over the place. Eventually I moved the shifter over to "S" position and forced it to 4th.
2) Transmission temps were ludicrously high (yep, I'm aware of the transmission cooler mod, it's on my list). With a 195F coolant temp, I saw 215F on a flat and level cruise, long hill pulls reaching 235F in the pan and as high as 250 in the TC.
3) The A760F 6-speed transmission is 6 speeds. But there were distinctly "more gears" than that. 4th had two different rpms about 300-500 rpm apart, same with 5th, etc. Like there was an over/under drive in there. A less appealing alternative is that when 4th/5th gear "unlocked" there was that much slippage through converter (which seems more likely considering the "ludicrous" temps reported in item2 above). Any ideas here?
4) I got about 10mpg towing. for reference, I easily achieve 19-20mpg round town 20-22mpg highway on when not towing. But when towing, the slightest headwind or grade forced me back to 4th gear which put my rpms up to about 2600-3000. My other tow vehicle for this camper has been a 5.9 Cummins which was a cake walk by comparison (dugh of course). Anyways, i expect that if i can keep the gx460's transmission locked it would behave much better, lower the transmission temps, and get another mpg or two. Hence the question up top.
thanks,
