Reading the forum convinced me to replace my alternator with a new 140 amp at O'Reilly's. It's been two weeks, we get ready to leave for a camping trip and the batteries go dead, no charging. Jump to start, no charge, truck dies. Take the alternator in, get it tested, 14.4 volts. No amp reading. Reinstall, same issue. I am taking the batteries in to be charged, but I suspect that will not solve the problem. My understanding is that the voltage regulator is part of the alternator? If so, wouldn't that have been covered by the bench test machine? I am really stumped. Anyone have any ideas? Thanks very much, George.

 

I've had the test machines say good when in fact the alt. was bad.

 

No amp reading? Huh?

 

The no current reading should tell them that it's bad since the test machines apply a load to the alt. Sounds like they may not have hooked it up correctly. Some of the auto supply parts help are of Jack in the Box caliber employees. Not putting them down, they just have zero automotive back ground.

 

Volts with no amp output = bad. Have me retest it or ask em to explain how it is possible with a load on the alternator. I bet they can't.

Steve

 

Thanks for the feedback. I may have stated this incorrectly. The bench test machine is not setup to provide an amp reading only volts.

 

Still sounds bad to me. Do you still have you original one, and did it work? Charge up the batts and try the old one in there.

 

If the test machine can't simulate a load it's almost worthless. Diodes can self heal when cooled down and without a load you're not stressing them.

 

So, Sears charged up the batteries and they showed good. Just installed, started the lady up and Scangauge II shows 11.8 volts?

 

Did you check them before you installed them? That may be where Sears charged them to. That seems a little on the low side to me. Do you own a battery charger? I know they are not supper cheap, but that would be a good tool to have around. Or, perhaps borrow one from a friend?

Edit: the alternator is running and showing 11.8 volts while the truck is running? That is for sure low. My stock alternator that worked just fine would never show that low even with the A/C running. Is this still the same alternator?

 

First of all, an tester that can not show amp output is useless. I could do that with a cheap meter and still know next to nothing about the charging system. A multi-stage charging system can show volts and little or no amps, as may be the case here. A battery at less than 12 volts is for all intents and purposes dead and an alternator putting out 11.8 with the engine running is not putting out. I bet you are reading nothing more than the charge level of the batteries after starting the engine.

Steve

 

Go tell them this truck takes over 200amp right at startup

No Amps isn't going to Fly

That's the only bad part with those alts lifetime gaurenty from a Parts **** If they had some quality control

 

Did you mean store or wh*re? That's funny right there, even if it was an accident.

 

11.8 volts is not bad on the gauge unless you are seeing that all the time. EDIT: 11.8 volts is not bad if he saw this when he first started the truck up in the morning. My truck is 12.6 vlts with Key Off and Engine Off. At Key On, Engine Off, it reads 11.8 volts. When I start it up and let it idle, it fluctuates from 11.8 to 12.4. After the glow plugs are heated up (1 to 2 minutes at most for my 6.0), the VLT reading on Scangauge should be 13.4-14.4 depending on the battery health.

If you are seeing 11.8 volts all the time, then:

A. The Alternator is bad.
B. The power cable that supplies power to the alternator is bad. Do you see Battery Voltage there with a meter?
C. The plug for the charging system or harness. It could be corroded or have a short?
D. Some other wiring issue. (Might be time to get the shop manuals if all of the above check good. I have the shop manuals for 2006 and 2007. I can try and get you the pinouts if you get this far and are stuck.

 

11.8 amps is not charging the battery.