Question for Automatic Trans Experts

bwg11, Jan 14, 12:56am
Finally reading the owners handbook of my FJ Cruiser after owning it for 5 years. The following is a direct quote from the handbook:

"Do not continue hill climbing or hard towing for a long time in the ???3???, ???2??? or ???L??? position. This may cause severe automatic transmission damage from overheating. To prevent such damage, ???4??? position should be used in hill climbing or hard towing."

The auto is a 5 speeder with positions for 1 to 4 and "Drive". I would have expected the using the lower gears, say second and third, would have been easier on the transmission and torque converter for heavy towing on steep hills than using fourth. Could this be because fourth is a 1:1 ratio and the lower gears are reductions which generate heat?Comments please.

2get1, Jan 14, 1:44am
My guess is the book is actually wrong.

I would have thought holding it down in 3 , 2 or 1 which is L would be better for along heavy uphill slog. Having it in 4th would suggest to me its going to be in to high a gear and continually changing down, then back up which generates a massive amount of heat and heat is what fucks auto transmissions.

Def not D as that would allow the convertor to lock up, if it has a lock up convertor and most modern vehicles do, once locked up you loose the the torque mulitipication effect of the stator and impellor running at different speeds. Solong uphill heavy tow you wouldn't want the convertor locked up.

The only reason I could think for them saying that is they don't want it revving its nuts off in a low gear and perhaps overheating the cooling system as a result.

frytime, Jan 14, 1:50am
That is correct bwg11. The Trans ecu will not let it hunt for gears. They have reasonably cleaver ecus in those. In d it will hunt but it 4th it will select what is needed. Ps they do good o's on the beach