Help! 1981 22r sr5 battery/sensor light on
 

So this past week I noticed that these two lights turned on as I was making my way home. I noticed that my battery voltage was down to 12v as I was driving. The next day i decided to test my battery while the engine was off i was getting 12v (normal). Then I turned on my engine and checked again and the voltage was between 11-12v even if i revved the engine it kept the same voltage. I tried to find the charge lamp relay on my truck but i couldn’t find it. I went for a drive that same day and my battery was not being charged by the alternator. I checked the ground from the chassis to the battery and the ground from the engine to the chassis and they were fine. Also to not my horn is not working. I checked the fuse box and everything is good. Also to note I was driving on the freeway the other day and as I came off from it both lights went off. When I restarted the engine the lights came back on. As of today I purchased a new alternator and I will be replacing it tomorrow. Hoping that this will solve my issue. If it doesn’t what else should I look at? Thank you for your time.

Update
 

A 12 volt charging system that is working good will charge 14 volts. When you turn on lights, or other accessorizes the voltage will drop slightly. Did you have the old alternator checked? If you bought a rebuilt from the local parts store there is a good chance its defective. Your voltage regulator could be causing the problem, not the alternator. I would have the alternator you just bought checked at the store you bought it from. Do you have a volt meter of your own to check the voltage, or a volt gauge in the truck?

I had the same lights and my battery wouldn't charge on my 83. My voltage regulator ended up being bad. I'd recommend testing its' resistance according to the factory service manual, that is how I was able to diagnose mine.

check and make sure that all electrical connections are tight and solid. I got stuck out in the desert once only to wake up the next morning and find that the wire harness came loose from driving like an animal.