voltage and Electrical Problems

ranger134x4 · #1 07-15-2012, 09:31 PM

I have a 2002 ford ranger 4.0 4x4 ext cab auto with 195xxx miles
Ok this is what’s happening:
The truck voltage keeps dropping. I put a volt meter on it and it reads 12.00V at the lowest with all the accessories running, but it doesn’t stall. The battery and the alternator are good.
I started pulling fuses with the voltmeter on it and I didn’t see any improvements in the voltage
The first sign of trouble was a 75A fusible link that blew out the one the lets the alt. charge the battery.
This is what stopped working:
1. Cruise control only works when it feels like it.
2. Now I put the truck in 4wd high or low and it stays in 2wd and the relay by the passenger door just clicks on and off and just keeps cycling on and off till I put it back in 2wd.
I hope someone can help me I can’t afford to take it to the shop. Thanks

blhde · #2 07-16-2012, 07:40 PM

I see 3 separate issues.

First pull the alt and have it bench tested, sounds like the regulator or brushes are weak.

Rangerman49 · #3 07-16-2012, 10:24 PM

Quote:

Originally Posted by ranger134x4

I have a 2002 ford ranger 4.0 4x4 ext cab auto with 195xxx miles
Ok this is what’s happening:
The truck voltage keeps dropping. I put a volt meter on it and it reads 12.00V at the lowest with all the accessories running, but it doesn’t stall. The battery and the alternator are good.
I started pulling fuses with the voltmeter on it and I didn’t see any improvements in the voltage
The first sign of trouble was a 75A fusible link that blew out the one the lets the alt. charge the battery.
This is what stopped working:
1. Cruise control only works when it feels like it.
2. Now I put the truck in 4wd high or low and it stays in 2wd and the relay by the passenger door just clicks on and off and just keeps cycling on and off till I put it back in 2wd.
I hope someone can help me I can’t afford to take it to the shop. Thanks

With everything turned on your truck you should not see voltage less than 12.9 vdc and between 13 - 14.5 vdc in normal use depending on the batteries state of charge.
Now that said, I would remove the alternator and battery and have them bench tested. The Alternator uses the battery as a reference voltage so if the battery is borderline it will make the alternator
look bad when it isn't!!! The battery should be fully charged before it's load tested..

FireRanger · #4 07-17-2012, 02:55 AM

You just said your fusible link blew. Of course you have low voltage. The alternator is not doing anything with that blown doofus. Nothing is going to work properly with low voltage. You need to replace that fusible link before you waste your time on anything else.

There is also a fuse in the panel under the hood for the alternator. And the third fuse related to the alternator is the air bag light / battery light fuse in the cab.

Rangerman49 · #5 07-17-2012, 06:56 AM

Quote:

Originally Posted by FireRanger

You just said your fusible link blew. Of course you have low voltage. The alternator is not doing anything with that blown doofus. Nothing is going to work properly with low voltage. You need to replace that fusible link before you waste your time on anything else.

There is also a fuse in the panel under the hood for the alternator. And the third fuse related to the alternator is the air bag light / battery light fuse in the cab.

I assumed he was smart enough to have repaired the fuseable link since he already found it!!???

FireRanger · #6 07-17-2012, 07:31 AM

I think you're giving him too much credit. He's saying his battery and alternator are, and at the same time reporting 12.0 volts with the engine running. One does not support the other.

If he did replace the fusible link already, then one of those other two fuses could be be blown. If so, the alternator will not have field current to begin generating power.

ranger134x4 · #7 07-18-2012, 08:20 AM

Yes I replaced the fusible link. The voltage I got was at the battery terminals not the alt. Now I had the alternator rebuilt I know it’s good, the battery I had tested advanced auto parts they said it was fine. maybe advanced is wrong, to me everything points to the battery, but when I walk in and have them test it, and they say its good, well that just stumped me. I will buy a new one when I get the money. Now I haven’t found the reason the fusible link went in the first place, and why now the 4wd won’t engage maybe its two different problems. Any ideas where I should start.

FireRanger · #8 07-18-2012, 10:34 AM

The battery is fine. There is nothing you've said indicating otherwise. Please check the rest of what I suggested before randomly throwing parts at it and wasting time/money.

Quote:

Originally Posted by FireRanger

There is also a fuse in the panel under the hood for the alternator. And the third fuse related to the alternator is the air bag light / battery light fuse in the cab.

When you turn the key to ON (not start), does the battery and air bag light come on? if no, the fuse in the cab is popped. If yes, the fuse is fine; when you start the engine, does the battery light stay on or go off?

blhde · #9 07-18-2012, 02:52 PM

Just because the alt was rebuilt doesn't mean they tested it or did it right. Pull it.

With the truck running and not going over 12v you have a charging problem. Soon its not going to start and your battery will need a some juice.

FireRanger · #10 07-18-2012, 03:07 PM

Quote:

Originally Posted by blhde

Just because the alt was rebuilt doesn't mean they tested it or did it right. Pull it.

With the truck running and not going over 12v you have a charging problem. Soon its not going to start and your battery will need a some juice.

That is exactly the "blind throwing of parts" I'm saying needs to be avoided. You troubleshoot before you start pulling parts and replacing them.

blhde · #11 07-18-2012, 07:50 PM

Quote:

Originally Posted by FireRanger

That is exactly the "blind throwing of parts" I'm saying needs to be avoided. You troubleshoot before you start pulling parts and replacing them.

I cant figure out if your in favor of testing the alt or not.

The 4wd issue is likely a fuse or the shift motor needing to be cleaned. Work on the big red flag of not charging first before you worry about the extra stuff the truck does.

FireRanger · #12 07-18-2012, 08:00 PM

I'm in favor of following the proper troubleshooting instructions I posted earlier. This is what you do before removing / replacing parts.

ranger134x4 · #13 07-19-2012, 05:47 AM

Ok thanks for the info. I’ll stop being lazy, and test and troubleshoot. And I’ll test the alt. when I get a chance to.