Well I think my 94’ lightning’s alternator might be on its last leg.

I tested my alternator tonight and it read about 30 amps shouldn’t it be reading a constant 45 or high amps????

Anyone got any suggestion on where I can get a direct replacement alternator with the stock 95 amperage????? I’ll regret replacing this with a oreilly or autozone alternator!

 

It all depends on the load. Was it fully loaded? Also, at what rpm did you test it?

 

no it was basically at idle (1500 to 2000 rpms) with nothing elses on.

 

oh the battery volt on the dash was at the n of normal reading. it usually sits at r or m and my battery is brand new.

 

I hate alternator’s!!!!!!!!!!!!!
On my 94’ lightning my alternator was getting worse so I had the bright idea to go an have it rebuilt yesterday and the guy promised it would be under $70 bucks to rebuild it. I pick it up today at the auto-electric shop it ended up costing me $136 in which the shop owner said the alternator was really messed up and said sorry for the cost!!!!

I get home and put it on and my truck ran great for about ten minutes (the dash voltmeter ran at M & A of N.O.R.M.A.L), but after the 10 minutes goes by its reads at N and under and not holding a charge and my brand new 1 hour old battery goes dead!!

List of things I think is wrong

1. alternator is crap and I should take it to oreilly’s have it bench tested

2. A short in my alternator harness

3. The electric fans do have shotty wiring!! Maybe that’s my culprit??? (I bought the truck with those fans 5 years ago and has gave me no trouble! Except the wiring job isn’t the greatest)



Any help or suggestions would be greatly appreciated! before my truck goes to the Ford dealership for costly repairs$$

And yes I know fans draw a lot of amps and yes I know I could’ve bought a reman alternator(life-time warranty) with the same price as the rebuilt one in which I probably will never see that money again!!! But I trusted the dude and he has been in business for over 30 years (BUT!!!! I got this sick feeling that I got screwed, but I won‘t jump to conclusions yet!)

 

How did you test the alternator? There are a variety of ways to screw up the readings. Basically, it should put out at least 13.5V and around 80 amps. The diodes also have to be good.

A bit of warning about parts store tests. I was recently (well, almost a year ago) at one of the larger national chains to have the alternator on my wife's 73 Camaro tested. While setting up the machine, it prompted the store employee to tell whether it was a part they had sold or not. He told it no and tested it. It came back bad. Just for grins I had him test it after telling the machine it was their part and it came back as good. We repeated both tests with the same results. You do the math.

 

oreillys tested it for me with a battery amp clamp

 

Did they put the clamp on a battery cable or the alternator output wire? If it was on a battery cable the number they gave you is the net output of the alternator. That is the actual output minus the electrical load on the vehicle at the time of the test. It should have been on the alternator output.

Speaknig of the alternator output wires, what shape is that connector in? They have a habit of deteriorating, sometimes to the point of catching fire. It's possible that you just need to replace the connector.

 

my battery cable


I think I found my main problem the alternator wiring harness could be fried!!! Well I got to order this from ford and have my rebuilt alternator retested to see if its still good.


thanks Silver Streak for all the replies!!!!!!!!!