I have a 1997 Ford Ranger Splash with 4 cylinder 2.3L engine. About 6 weeks ago the check engine light came on. The code came back that it was my ERG valve. First, I replaced the ERG valve. After a couple weeks the check engine light didn't go off. To reset the light, I disconnected the battery for about 15 minutes, then hooked it back up.

The check engine light came back on the following day. But there was now a new problem. When I went out for lunch, the truck wouldn't start. I moved the terminals on the battery a little thinking that maybe I didn't tighten them enough the night before, and then it started right up. I turned my A/C on low and pulled out of the parking lot and my battery level dropped from about 1/2 on the meter (~13.1v) down to about 1/4th (10.5-11.0v. I've had this truck for over 10 years and have never seen the batter meter move out of the 1/2 spot.

The next weekend, I replaced the DFPE sensor. While at Autozone I had them check the alternator and the battery. They said both appeared fine. Replacing the DFPE took care of my check engine light. Hasn't been back on since. My battery level is still dropping on occasion though.

This past weekend, it was going up and down non-stop when I drove to the store. On the way home, it barely moved.

I took it to a mechanic on Monday and he was convinced it was the alternator and he replaced it. I drove it yesterday, and it still does it. Last night I bought some new battery cable connectors and replaced them to ensure they were ok. I drove around my neighborhood and the truck did the same. Sitting in my driveway, it was running 13.1v. I got the truck up to about 40mph and hit the brakes fairly solid, and it dips to about 11.0v. It seems to only do it when I slow down.

I took it back to the mechanic today and he said he doesn't see anything wrong with it. I asked him if the belts were tight, and he said they were fine.

Assuming he doesn't find anything, I'll probably have Autozone check the battery again.

Any ideas on what I should look at next. I'm at a loss now.

 

I don't trust Autozone's tests - I question whether or not they test these things under load.

That being said, since the alternator has been replaced, I would have the battery load-tested - I'll bet that's your culprit...

 

Welcome to FTE.

You may have more than one problem.

Your right to have suspected the battery post to cable clamp connection, after you had it loose & from the clue you provided about moving the battery cable & having it crank.

You said you replaced the cable clamps & those kinds of connections are a temporary fix only & are frought with electrical problems & you didn't indicate that you also checked the cables connections on the other end.

You really need new cables as a permanent fix if you've cut the molded on clamps off.

With the charge voltage dropping on a stop, the battery electrolite level belongs on your suspect list, as well as the battery SOC, as the 11.0 volt reading suggests the battery soc is down, electrolite is low, or you have an internal battery problem, like a cell to post connection problem, or a cell opening up, or shorting out, so have a proper load test done at AZ when they do their electrical system check up.

I hope you had the new alternator output/load tested before you left the store with it.
Just because its new doesn't automatically make it good.

Your also wise to suspect the alternator belt tension & your belt tensioner has a tension range mark cast into its frame, so thats easy to inspect to see if belt tension is within range.

Some thoughts for consideration, let us know what you find.

 

I'm with Pawpaw on the possibility of an internal battery fault, especially since it acts up when you stomp on the brakes.

Also, check to be sure that the battery cannot move around any when you grab and try to move it (have you been hearing any thumping sounds when going around corners fast?). I've had batteries slide around loose even though the clamp bolts were tight. If you end up with a new battery, you don't want it able to move at all.

 

bcurry:"I took it to a mechanic on Monday and he was convinced it was the alternator and he replaced it. "

When that didn't fix it, did he put your old alternator back in place? I'm !*!SUre*!* he 'tested' it before replacing it and charging you for the service. /sarc
Alternators are simple to test, and have 1 moving part. They generally are NOT sensitive to motion as they ride on an engine that vibrates the whole time it is running.
I would have looked for a loose connection. The voltmeter displays voltage it sees, not necessarily what voltage the battery is producing. Get out your own meter, and measure resting and engine running voltage. Look around near the battery for connections that may be loose, or corroded. My suggestion, worth as much as you pay.., is much more likely than battery disintegration internally. I've only had them work, or short out 'right now' to where they could not even be jumped except by a wrecker with LOTS of amps. Never an intermittent, but I guess I'd better be prepared for new things...
tom