hey, I have a 97 4x4 with 360 and auto trans. I have noticed that the tranny will kick down from overdrive to 3rd manually with no problem, but when I turn the overdrive off with the button on the dash, the tranny slips and sometimes even falls out of overdrive all together. Turn the button off, step on it again, and she downshifts and holds until I let up on the accelerator. Any experience on this one? Is this a simple electrical problem, or is the tranny starting to go? any advice would be greatly appreciated.

 

When you press the button it's supposed to kick back out of overdrive. I guess I'm not following.

 

Tranny works fine when you push down on the accelerator and kick the tranny out of overdrive yourself. It does not hold in 3rd when you turn the overdrive off with the button though. so if you kick the tranny out of OD and into 3rd yourself, then push the button to keep the overdrive off, it wont stay off. It slips in and out of OD anyways. I apologize for the confusion, these things are hard to put into words sometimes...

 

I'm not sure I really understand what problem you are having but I am assuming you have it shifting into OD all the time regardless of your OD button setting and erratic at that? If this is the case make sure the OD button switch is good,just because the lite goes on/off does not mean it's actually switching-check it with an ohm meter,the OD solonoid inside the tranny pan may not be venting which causes erratic behaviour as the screen can get plugged on the solonoid valve.The conditions which must be met for proper OD operation are-coolant temp sensor must be atleast 65 degrees,VSS sensor must read atleast 25 mph,TPS sensor voltage is compared against engine speed to determine when to engage or disengage OD,the engine speed signal comes from the distributer pick-up and the whole she-bang is also routed thru the brake pedal lite so when you depress the brake it wil shift out of OD. I hope this helps you or atleast can give you a direction to go in.Good Luck! OD pressure factors into it also.

 

That's thru the brake pedal lite switch -sorry

 

Thank you for the detailed response...I will start by checking the switch when I have time. I just had the dash apart for somethin else and didnt even think about checking it. Hopefully its not the tranny going, thats my main concern. I will keep your post and refer to it as I get the time. That gives me a good point in the right direction.

 

Sounds like your torque converter is unlocking. I would definately change your TPS, its cheap, and it causes alot
of problems in shifting and tranny surging