I just bought a 1998 Ranger 2WD, 2.5L, 4sp w/ OD. The guy at the small car lot where I found it told me all he had done to it was replace the alternator because it had bearing noise and it does have a new alternator.
The problem is when shifting out of first into second or going from second to third if I wind it out slightly the battery light lights up and the voltage drops off. I haven't gone digging into it yet, because fixing it is the sellers responsibility and I don't want to tamper. The belt seems to be tensioned correctly and doesn't appear to be slipping when the battery light is lighting up and the battery checks out ok.

What should I look at next?

 

Welcome to FTE!

Check all wires to and from the battery and the alternator, look for corrosion and/or a loose connection. Make sure the battery ground is clean. Try wiggling the wires with the engine running to see if the battery light flickers. (Obviously you will need an assistant to do the wiggle test).

Also, check the alternator fuse (location #14) in the power distribution box (i.e., the black rectangular fuse/relay box under the hood) for a loose connection by wiggling the fuse with the engine running.

And don't rule out a bad alternator, either, simply because it's a recent replacement. Parts stores hand out bad units all the time...

Hope this helps.

 

Could be several things, but if fixing it is the sellers responsibility, why not just let him fix it? It is probably the regulator. Like Rockledge says, just because it has been replaced doesn't mean the new one works. Also is it a new alternator or rebuilt. A new one is less likely to be bad, but not always. A digital voltmeter is a valuable tool to troubleshoot this type of problem

 

In my history of repairing my own vehicles another bad alternator will be the fourth replacement alternator that was no good.
The car lot where I got this truck uses a mobile repair guy that works out of a trailer and truck. I've seen him here at work before doing brake jobs in the parking lot. This friday will be one week since I bought the truck and the weathers been less than fair, so I'll just have to be patient.
I posted here knowing there was enough combined miles behind the wheel and under the hood to have seen something like this before. Who knows this repair guy might not be a Ford-man. I'll keep my eye on him. My brother-in-law is a real mechanic so I'm usually the assistant, but I'm an expert on getting the run-a-round. I feel confident the dealer and service guy will cooperate, but if not I'm going to move ahead on my own. I'd rather do that than have someone under the hood with a grudge.
I also noticed that one of the aftermarket products offered to the guys and gals wanting to increase the power of these engines is a wiring kit for improving grounding in the electrical system.
I bought this truck because I had to park my '67 F100 that was a daily driver until last week. I know that these two trucks are nothing alike, but it's interesting that after 32 years they still have some of the same quirks and oddities like weird noises and electrical issues.
Thanks to you both for your useful input and if you can think of anything else on the truck I should look at based on the sampling this forum offers please advise.

 

Does the heat work in all positions (cooling/heating)? I'd reccomend reading through a few "air blend door" threads to get an idea of how to make sure.

-Jim

 

I read what I could find.
I do have heat . Lots of it and the temp selection **** does make changes to the temperature. Air works too (cold A/C).

thanks. keep 'em coming. If these problems occur it's better to be warned. It saves diagnosis headaches.

 

No word from the mobile mechanic the dealer uses, so over the weekend I went by our local "chain auto parts store" and had them hook up the charging system tester. I had already removed and cleaned the battery terminal and cables and they were corroded. This seemed to raise the RPM level it took to get the battery light to come on and the lighs to dim.
The battery and alternator both checked out fine during the normal procedure and with the RPM high enough to get the battery light to flash.
So now I'm guessing it's a fulty ground thats not able to handle higher current draw somewhere in the main ground, coil ground or who knows where ground.

I need not only a wiring diagram, but a wiring location diagram so I can spray contact cleaner on various connections hoping to see some change. Any ideas?

 

Try getting a Ford manual off ebay.

 

I sprayed electrical contact cleaner on every connector I could see and the problem went away or at least it does it at an RPM level beyond normal operating range.
It doesn't surge anymore at highway speed and the headlights seem brighter. I'm still going to get a new battery. I think the one in it is original as it is a Motorcraft, looks old and the green eye is kind of yellowish.
I found a factory service manual on CD, which is nice because you only have to print the pages needed.
I am very happy with this truck!