Fan turns off and on while car is not running. This happens at any time of day or night. Even when car hasn't run for hours. Car is an 84 coupe. Eventually runs battery down. Coolant switch, relay or other idea? Also, can't get my code reader to work on this car. Keeps saying it is unable to connect. My code reader is an Autoxray CodeScout 2500. TIA

Hello
A bad ECM will cause both of those problems. But as for the fan there's a relay on the driver side inner fender under the master cylinder make sure it's not been poorly hot wired. there are 4 wire going in to it.
David Steele

I got the code reader to work.......changed a loading setup. Have a new relay on it. Got new switch coming tuesday. Hope that is it. Code reader showed no codes..all normal. Hopefully not the ECM. What do you think.

Prom runs the fan, not the ECM. But shouldn't run when key is off. I'd say you're on right track with relay, you can test easily or temp switch.

I hope you get that taken care of, I can't stand computer problems:mad5:

I would almost gauruntee that it is your relay!:cheers:

Between the relay and new switch....problem solved. Thanks