Are you saying that if you have the KEY OFF and you put an amp meter between the B+ post on the alternator and the wire that should go to the B+ connection, it draws 0.5 amp? That would kill the battery (at least get them down below the critical 10. VDC level) in a week or so. I can't check my truck (due to a bum leg and a lost Fluke DMM ), but I am willing to bet that other folks won't get 0.5 amp reading with key off.

 

Neal, yeah, that is exactly what I'm saying

So, took that the truck to the alt mfg and showed them what was going on. I pulled the alt and they check it again. No problems...

They were cool enough to give me another alt to try out. What do you know, it works as expected. We just swapped them out and called it even. Problem fixed.

For those of you who have suffered through this thread; here are my lessons learned:

1) When checking for system current leakage - pull the positive terminals off both bats and install the meter between one bat and and the pos cable.
- use something like a 10A scale or you will blow your mA meter fuse...
- It was speculated that 75mA leakage was within spec (??), I am now seeing 150 mA. Maybe I still have a "leaker" but I know I've at least killed a 0.5 amp leaker. Will take a look at the 150mA when the weather warms up.

2) If you pull all of your fuses and relays, under-hood and in-cab, and you don't fine the offending circuit, be advised that there are circuits; like the starter and Alt that bypass the fuse panels.

3) Easy to check the alt, at the alt, and the Starter at the starter relay on the fender well. Just realize that the alt circuit shares a post on the starter relay. (Two white wires on the relay hot side) So when you pull the bat cable off the relay, if you get a current drop, it could be still be the alt...

4) Even if the alt checks good...it might not be.
- Nothing better than being able to demonstrate what you are seeing to the alt guy...

5) Last but certainly not least, the folks on this forum are top notch. Thanks to all who pitched in. Best regards.

-Mike R

 

Thanks for posting this "bad out of box" alt problem.

This would suck if you get an alt online and can't go to the supplier and actually show them what is happening.

Reps sent for your perseverance and finally getting to the root cause of the problem.

 

Did you ever mention the BRAND of alternator? You were lucky to have the alternator mfg right near you! WOW! Lucky.

Did they speculate as to what was wrong with that unit?

 

Don't know the brand. I was dealing with Romaine Electric. Big outfit, good reputation. I went with them to get one of their hand wound units. Don't know how much of the unit they build..? They took it back into the shop after seeing what it was doing in the truck and could not duplicate the problem?? Real head scratcher.
They were good enough to exchange it for me w/o a receipt or any proof of sale on my side. I'd use them again in a heartbeat.

http://www.romaineelectric.com/

 

Howdy yall,

I didnt wanna start a new thread since the topic here is right up my alley. (Unless i should?) I just bought an '02 7.3L F-250 in January. SuperCab, 139K miles, Auto. EXACTLY what i was looking for and I love the truck, but she started giving me problems. Heres a rundown of what happened:

(Note: Prior to this, NO problems whatsoever. )
- Wife drove it to work and back one day, wife said it didnt want to shift out of second on the way home.
- Went to start in the morning, dead stick. I mean so dead, electric locks didn't work, no dome light, nothing.
- Picked up two new Interstate Mega-Trons (1000 CA's/850 CCA's- after consulting recommendations here on FTE from yall ) and installed 'em, figuring the batteries were old and it had been cold. Anyway, truck fired up no problem. Took it for a spin to the gas station, ran and drove, shifted all fine. Parked it, went to bed.
- Next day, same thing. Dead stick. Still have old batteries, so threw them on the trickle charger. Put them back in the following day, started her up and took her to O' Reilly's to check the eletrical system. They said the alternator was working but couldn't check the rest cuz I didnt want to shut her off and get stranded. Drove home, parked.
- This time, she started in the morning. Drove to Wal-mart (maybe 10 min drive). Came out, started up fine. Drove across the street for lunch. In the restaurant maybe 30-35 min. Dead stick.
- Called for a jump, guy came out and threw a multimeter on one of the batteries during the jump. System registered a max of 8.5V while charging unless he revved above idle, then about 11.5V. Didnt check amp draw, though.
- Have Sidewinder electric steps w/ power running straight off DS POS battery terminal with an in-line fuse. Popped fuse out during jump to open the ckt, no change. Draw not from there.(Note: Only other aftermarket electrical is an old Edge Attitude tuner and a Pioneer radio.)
- Got enough juice in her to start up and drive home. Again, ran fine.
- Got home, system didn't even have enough juice to retract the electric steps after I shut her off and got out.
- Charged Interstates, have them standing by.

I really dont want to spend the kind of money for the dealership to look at her, and i'd rather get my hands on her myself, but Im also pressed for time. Mrs and I both work and our schedules conflict. I am pretty mechanically inclined and have some electrical knowledge. What equipment do i need (and recommendations) to find the problem, and where do i start looking? Thanks for whatever advice and assistance yall can provide!

Chris

 

Welcome to FTE. Seeing MR5x5 fixed his problem, we can just move on to yours...but generally it is better to start a new thread.

A lot of the info you need is in this thread. You will need a DMM (digital multimeter) and some time to figure this out. Take a charged set of batteries in the truck but don't connect them yet. With key OFF, hook the batteries up but leave the positive off one of the batts. Then put the DMM in AMP mode and place between cable and battery. Now measure the amperage draw...should be down in the milliamperes range. If it is not, then have your assistant remove a fuse at a time until the amperage draw drops...now you know the circuit with the high amp draw. Let us know what you find.

In all of this, I am assuming you have checked all the cable connections for being clean and tight. I'd disconnect the steps and amp them out separately.

 

The alt is shot.
It is not delivering the amperage to keep the batteries charged.
Do a load test with all accessories on.
A voltage of less than 13 volts is too low at idle.
the amperage needs to be at the upper range of the rated capacity when under load.
You are killing the batteries with the constant deep draw down.

 

Just be sure to do the voltage test AFTER the glow plugs have timed-out.

It just confuses things if the GPs are still on.

The draw-down itself isn't what will kill the batteries, it's the amount of TIME that the batteries are left at a charge-state of under about eighty percent that's the real important thing. Under that figure is where sulphation takes its toll on reserve capacity.

Pop

 

Thanks for the welcome, and I appreciate the tip! I just didn't want to be the guy starting a new thread over something someone already asked. i know a lot of people do that instead of searching for the answer to their question ahead of time.

Any recommendations on a good quality, reasonably priced multimeter?

Is there a second fuse box besides the one under the steering wheel?


I know, and i dont want to ruin those brand new batteries! The alternator looks pretty new, but i know that doesnt always matter, esp. seeing the posts in this thread. Would the alternator just crap out all of a sudden? How do i check it?

Thanks Pop. The GPS times out 2 min after key is turned on, correct?

 

Yes. Under the hood, drivers side top. Black plastic cover. Next to the Master Cylinder.

 

That's correct. That's the maximum they would be on, but if the engine's warmed up, it could be much less (or not at all).

But if you wait two minutes, you'll be assured that they have shut off.

Pop

 

One easy way to check the alternator is after it has sat for a while, and the engine is cool you put your hand on it and feel it. If it is bad it will be warm to the touch. You might have to check it after charging the batts and putting them in if it is killing them over a few hour time period.. that must be a heck of a draw.

 

Well, it looks like my first order of business is picking up a digital multimeter then! Thanks guys for all the help. The diagnostic process sounds a lot less overwhelming than i was expecting. I'll definitely get back to yall on what I find out, but it wont be for a few days, until I'm off work on Monday. Wish me luck. Again, thanks.

Chris

 

On your 2002 the only fuses are located under the dash.

Here is a comparison between a cheap Cen-Tech meter from Harbor Freight and a very expensive Fluke meter checking batt voltage. For checking batts and alt output the Cen-Tech (Under 10 bucks) is good enough. 0.05 volts won't really make a dfference and who's to say which one is correct?