Im running a 91 4runner 3.0 Auto, I am aware that the truck needs to warm up compreltly before the O/D kicks in, but im getting a strange issue with my O/D

When the truck is warmed up and I start cruising down the highway the truck will shift into O/D just fine, but after about 5mins of driving it will kick out of O/D and not shift back into O/D, until i've slowed right down, driven around town, shifted through some lower gears, then back up to highway speeds, then the same thing will happen with it shifting out of overdrive.

Im wondering if maybe the trans heats up and shifts out? Im not going up any hills or anything or putting any different load on the truck, just a straight flat section of road. Any advise?

 

Have you checked your fluid?

 

I think the ECU will still allow the tranny to shift into OD in an overheated condition. Any reason you think its overheated, is the tranny temp light coming on?

I'm wondering if the coolant cools down and shifts out until its warmed back up again. The ECU must see a hot temp from the coolant temp sensor for it to allow the tranny to shift into OD. Maybe the thermostat is stuck open overcooling the coolant at higher speeds or maybe the temp sensor is faulty.

 

I didn't want to start a new thread since this is so close to my question, but I am new to the Toyota Auto tranny and wonder if it not shifting into OD until it hits a certain temp is normal? Mine does this, and I figured my tranny was getting ready to go out. Is this not so?

 

From post #3

 

yeah, I saw that and that's what sparked my question. I guess since no boby else has chimed in, that's the accepted answer. Not that I am complaining at all, it just means I don't have to baby my tranny as much since it's normal.

Thanks.

 

If you're looking for a second opinion, the A340H transmission will not shift to O/D and the torque converter will not lock up until the engine coolant temp reaches 70 deg C (158 deg F).