2nd Gen Overdrive Issue

[Nodd]

'95 SR5 V6 3.0 automatic 4x4

My overdrive seems to have a mind of its own. Usually for the first 10-20 miles on the highway my tranny refuses to shift into overdrive. The RPMs read around 3.2k at 55mph. Then when she's warmed up a little the overdrive kicks in & the RPMs drop to 2k something.

I've owned manual shift vehicles for the last 15 years so I'm a little out of the loop with automatic transmissions. Is this normal? I was thinking maybe its supposed to do that to help warm up the engine/tranny?

Yes I've played with both the O/D button on the shifter & the ECT Power/Normal button. Neither seems to make a difference when the motor is cold.

Is this normal & if not any ideas on why its locking me out of overdrive?

 

[fourwd1]

Is this normal? I was thinking maybe its supposed to do that to help warm up the engine/tranny?

Yes, it's normal. Helps the engine warm up quicker, reducing emissions.

 

[Nodd]

Yes, it's normal. Helps the engine warm up quicker, reducing emissions.

Okay that's what I thought. Thanks.

I just did a little reading on this subject (probably should have done that before posting, oops). It sounds like my thermostat maybe stuck open & that's causing the engine to take longer than it should to get up to temp. I'm going to replace the thermostat & see if that helps.

 

[Nodd]

Well apparently I was kinda right. My thermostat was indeed stuck open. VERY OPEN...

Apparently the PO felt this was the best fix for an overheating issue. Please don't do this sorta thing people!

Anyway I installed a working thermostat & now my overdrive kicks in shortly after starting the truck. No more waiting 20 minutes or longer. Should save me a bunch at the pump. What I've yet to see is if the PO's overheating issue returns. Fingers crossed.

 

[fourwd1]

No t-stat would definetely cause it to take longer to warm up.