grover
grover GRM+ Memberand Dork
12/20/23 5:39 p.m.

Hey y'all. 

I'm sort of stumped.  During my saga with the cooling system on my ranger I made a boo boo.  I was rushing and tried to remove the alternator before unhooking the battery.  Of course I know better, but again, just diving in and forgot.  I shorted the hot lead from the alternator on the body of the alternator.  I figured it was cooked and sure enough once I got the car repaired I had a low battery and a battery light.  

I first charged the battery and that did not work.  Then I got a new battery.  Then a new alternator and battery.  Same result- low on the volt meter on dash, batteries don't seem to be charging via the new alternator same as old.  

One strange phenomenon is that if I run the rpm high (it's a manual) the light will go off and stay off for a while if it's run at semi high rpm for a bit of time.  I don't have a tach on this truck- but it doesn't seem to be crazy high rpm.  The battery light will stay off until you turn the truck off.  Next time you start it....battery light on.  

I have been trying to keep battery charged with a small charger overnight.  

The last factor is this- this truck has a bad radio and I think in the past it may have drained the battery some.  So tonight I removed the radio to eliminate that variable- I need a new one anyway.  

I have checked all fuses, connections and wiring to the alternator.  

I believe the regulator is on the alternator.  Alternator is from O'reilly and it was not a reman- but I know those can be suspect.  I can change one out in less than 10 minutes at this point.  

Thanks for the help! 

Ranger50
Ranger50 MegaDork
12/20/23 6:24 p.m.

If the battery light doesn't come on, that's the problem. Replace the bulb. If not, you probably burnt up the rectifier. It founds out against the case.

grover
grover GRM+ Memberand Dork
12/20/23 7:47 p.m.

I thought so on the first alternator- but this one is doing the same thing. 

Ranger50
Ranger50 MegaDork
12/20/23 8:38 p.m.

I'm looking at a diagram.... is the 175a maxifuse ok? It shows connected externally between the battery power and alternator output back into the underhood fuse block.

grover
grover GRM+ Memberand Dork
12/20/23 8:44 p.m.

I've not checked the megafuse. Will do in the morning. Nice callout! 

grover
grover GRM+ Memberand Dork
12/21/23 2:03 p.m.

100% megafuse!! Cost just under $6.  I'll be honest, I had never heard of that.  

Thank you Ranger! I guess you lived up to your name! 

 

Ranger50
Ranger50 MegaDork
12/21/23 5:20 p.m.

You're welcome.

I've worked on Fords on and off for 35(?) years now. There is always a quirk to them.

Nockenwelle
Nockenwelle Reader
12/21/23 6:53 p.m.

That protection fuse seems to be HIDDEN in a lot of 80s and 90s Fords. It did it's job of preventing a meltdown.

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