89 Tempo electrical probem

I have an 89 Tempo. The lights (exterior & interior) are not as bright as they should be. Turn signals & wipers much slower, also.
I had this problem 12 days ago, aslo. I took the alternator and battery and had them tested (Battery was also charged). They both tested good. Then everything worked for until this morning, and then, the same problem again.

Any ideas on what to look for, or look at next? I'm not really up on automotive stuff and the lingo, so any help would be appreciated. Thanks.

Welcome to Automotifve Forums! Whenever a light or anything electrical goes dim or slower it almost always is a bad ground. It could be a bad ground at the battery or it could be a bad ground wherever the negative cable connects to the block. Do a visual around the engine and look for a wire or wires that ground to the block. Mine has a ground to the alternator bracket for the headlights. So start at the cables on the battery and look backwards for a poor ground. The reason I think it is a poorr ground is because it is affecting so many things. Hope this has helped. Again, start looking at the grounds from the battery itself. On my Escort there is a ground harness everything is hooked to so check for this multiple ground thing back from the battery. If your car was mine, I would run a fairly good sized wire from the block to the firewall. Clean the paint off before you hook it up. This will ensure that the car and engine are both grounded to each other. Also, this will probably fix your problem. Dave

Yeah. I agree. check the ground wire and see if it's good. If it looks good on the exterior, then maybe shave a small little chunk(not too big. just big enough you can see the copper, and be able to tape it up) and see that the wire isn't green. If the wire is green, then you got a rotten ground wire.

Also, try cleaning your battery terminals and see if that helps. better yet, put new battery cables on all together. It probably should be done on a car that old, anyways.