New here and hello to all. I recently purchased a 1990 2dr accord it has 237,xxx miles on the 4cyl auto. The car is in awesome shape and the engine runs perfect. I do have a issue with the sport light flashing on the dash and it seems the car won't shift into overdrive. At 65mph the rpms are around 3k or so. The sport button on the shifter doesn't to anything.. Any ideas? Thanks for any help.

That will probably be related to the Transmission Control Unit (TCM). The TCM is the computer that controls the automatic transmission and it’s located next to the car’s main computer (ECU). There is a way to do a self-diagnostics by connecting a jumper wire to the Service Check Connector and then when you turn on the ignition switch and the Sports light will blink giving the code/s of the specific issue. I don’t know what the codes are for the TCM because this is mostly done by the dealers but I think the TCM codes range from 1 to 15.

I suggest having it checked by professionals but chances are the TCM will need to be replaced. If you are a DIY type of person the TCM is located under the carpet at the front passenger side (bellow glove compt.).

I think that's a typ. issue for 90/91 Accords.

Welcome to the forum!!!

DO NOT replace tcu, you need to diagnose the problem. Jumping the service connector is very simple (all you need is a paper clip or thin wire) and you basically have to count the flashes.

Here is a link showing the procedure, just count the S flashes for codes stored on the TCU. You can repeat and count the codes stored on the ECU by counting the check engine light flashes.

http://www.dhost.info/accordinfo/howto/cel.html

Post that code on here an we can give you more advice.

have it read..... the most common problem with those is the speed sensor.