89 a/t transmission not going into overdrive!!

[baxterman]

I need some help, my 240 will not go into overdrive the car has 246k mileage I've never had any troubles with shifting. In the last month the car needed to warm up before it would shift into overdrive. Before I would cruise at 70 @2900rpm, now @ 60 I'm at 4400, are there any sensors that could be causing this. Could a transmission fluid change help?

[Encryptshun]

Change the transmission fluid and see if that helps. If not, with 246K miles, you should probably rebuild it anyway.

Or better yet, swap in a 5-speed.

[elo240]

Does your overdrive light flash repeatedly when you first start the car? If it does then you may have a sensor problem. The OD light is like the check engine light and there are codes you can pull. Check the FSM for more info. If the OD light doesn't flash multipal times then its probably and mechanical issue.

[baxterman]

Overdrive light does not light at all, it never did even when o/d worked. Should I bother checking o/d switch to see if that could be bad?

[elo240]

first check the bulb.