Need help... Bronco stuck on worksite... alternator maybe...

[89dieselbko]

Did some searching, did some work. Dont know what the issue is.

My charge warning light *battery* is on. Batterys are not charging, but arent losing charge. HOWEVER i can run and drive it in the daytime without issue. Its raining tonight, trying to head back to the travel trailer, and Headlights + wipers = turning off fuel to motor. Cant go without either in the pouring rain. I have checked all the ground wires, all the connectors. It seems the alternator is putting out just enough juice to keep the truck running as long as the load is minimal.

During my work trying to isolate the problem, i found a random stud with a nut on top of the alternator. its REALLY lose, dont look like a wire goes on it, cant seem to locate it on any pictures on a truck. I went to advanced auto website and it shows the stud, and on one alt its labeled as *ground* but i dont remember a wire ever being on it, and my maglight is dying. is there for sure a wire im missing that slipped off maybe? was beating it a bit to get it on the side of the ravein hauling 7 people and a welding setup + hauling 500 gallons of off road diesel for our equipment, im thinking i might have knocked something loose. Is there a wire on there that i should have? hopefully someone can get back on this quick, if so i can manage to get this fixed and NOT have to sleep in my bronco, in the rain!

The motor is from a 90 F250. its NA, and the alternator is a reman with about 1300 miles on it *switched it when i did the swap, cant remember if i ever had a wire on it.... Driveworks brand.

[Wyreth]

There should be a lug for the battery, the plug for field, and then the wire lead should have a metal plate that bolts to the ground. Or so it does on my 87.

Did you replace the voltage regulator when you changed the alt? That can cause that problem too.

100_1769.jpg

[89dieselbko]

nope just the alternator, i found a plug, fits good on the alternator stud... but it runs on top of the motor, seems like a funky way to run a ground on that alternator... worst part is i have it idling now, with my power inverter going to power this lab top, and fan on to bring in some cooler air and get rid of the humidity... been out to check the battery and that 4 times in the last hour or so and its sitting at 12.56 (low i know, but alternator has to be doing something as its not dropping, but not increasing. That picture looks different then my alternator, its showing 3 wires, mine has 2 in the top plug the back on is paralle with the fenders, and the front one in paralle with with core support. Still combing every picture of the 7.3 to find a half decent look at the alt to get an idea why i have no wire, or if i indeed found the right one *dont want to plug it in and get MORE stranded if i fry something. At least right now i can leave in the morning when the suns up and i dont need lights.

[opusd2]

Did you ever put a voltmeter to the batteries with it off, and with it running?

Unless I'm half asleep, I think you need to check out the difference.

Then with the engine running, start adding accessories. See what kind of drop you have.

[Dave 001]

mine has 2 in the top plug the back on is paralle with the fenders, and the front one in paralle with with core support.

Vehicles with an ammeter only used (2) wires....a field wire (usually orange) runs from the alternator to the voltage regulator and a heavier gauge wire which connects to the alternator stud (this is the output wire).

If it's wired correctly, replace the regulator (either with a new one or a known good one). A new one is not expensive, about $15. And retest.

I'm having problems uploading pictures....don't know why. Google "Ford 1G wire diagram". You'll get all the pictures you need.

Although a ground wire gives you a warm cozy feeling, the alternator grounds just fine through the mounting brackets and a ground wire is usually not used.

Dave

[OLDBULL8]

A battery charged will measure 12.56 with no load on it. From what your saying about the Alt. when running that it's putting out only that 12.56 volts, that is the battery voltage your reading, it may have blown a diode. If you have an external voltage regulator, do this, from the battery terminal on the Alt., with a piece of wire jumper that terminal to the F (Field terminal),with a volt meter connected to the battery, it should read full output of 14 to 15 volts. If it does then your regulator is bad or the connections on it may be loose or corroded. Without an external regulator you don't get full voltage output (4-15 volts) then the internal regulator is bad or a diode has blown. You need that ground wire from Alt. to battery neg. or a good ground someplace.

[89dieselbko]

OK well i drive home this morning, around 2.5 hours and when i left the worksite batterys were LH 12.59 RH 12.47. Had the alternator tested at advance on my way. it failed. No load 12.28 and loaded 12.28. But my batterys are both higher than that. and my meter is reading more like 10 or so, hard to tell exactly.

I checked my batterys while they were disconnected to see if i had a bad one, in case anyone was wondering. The inline fuse i replaced even though mine looked ok, no change.

Going to try the jumper wire and see if im getting full charge, just as soon as my burgers are done cooking. Will also go back and double/triple check all my grounds and other connections, hopefully make some progress!

Happy 4TH everyone

[Dave 001]

Going to try the jumper wire and see if im getting full charge, just as soon as my burgers are done cooking.

This is a good test but DON'T rev up the engine while doing it. With no regulator to limit the voltage to 14.7, the voltage will easily climb to over 100 volts and things will start frying....and quick. Good bye E4OD computer. Good bye radio. Good bye light bulbs. Etc.

Dave

[chvycmnslvr68]

If you want a good dependable alternator that is simple to adapt a Leese-Neville is self activating and only requires the hot to the battery and a ground wire ... I have a 160 amp continous duty cycle and it only cost about $140 brand new .. these are designed for semi trucks and will run practily forever .... I just had to have a pulley machined to fit the larger shaft for my belt set up .... ;

[riotwarrior]

If you want to upgrade....get a 3G alternator, the are inexpensive, used by Ford, available at almost any parts place and it is a simple hookup too. I have done the conversion...and would NOT GO back to anything less. Yes the LEESE NEVILLE is a fine unit, but if you are out and breakdown, not all parts places have one or wreckers for that matter....

JM2CW

Oh ya...and as good as the ALT grounds through the block....I STILL run a ground wire from the case to the battery! JUST cause I am OCD that way! WHEN GOOD ENOUGH ISN'T.....OVER KILL IS!!!!!

[Wyreth]

WHEN GOOD ENOUGH ISN'T.....OVER KILL IS!!!!!

No such thing as overkill.

[89dieselbko]

OK, so the jumper wire test, no go, didnt change anything. if im honest when i first contacted the jumper *from alt to + term* it would drop to ~8 then go back to 12.51. Thats what its running at today. I cranked the radio, turned the high beams and 4 ways on to drain the batterys down to 11.5. Started the bko and its charged the batterys back up to 12.51 lol. Advance is stumped, i stopped up and tried a new regulator anyway, and it didnt do anything. RE checked grounds. cleaned up the grounds for the regulator. All that good stuff. still nothing, i ordered an alternator (100 amp, $51 my price with business acnt) will try it tomorrow.

I have a 3g i used on my 302. need to change it to Vbelt, and redo the wiring for the 7.3. i havent bothered to read up on the swap yet, at least not the wiring changes i should add. external reg to internal, then i gotta redo the fuse and all that stuff, its in the future, but im still in the shake down, making sure everything is working. Its not time to start on upgrades yet. Monday was the first day driving to work since the swap, 2 hours to pittsburgh no issues, campsite to worksite no issues, then last night issues lol. the alt on it is a reman from jan 2011 wouldnt figure its bad, but i have ruled everything else out. Unless im missing something, will know tomorrow if its the alt, and go from there.

[89dieselbko]

forgot to add.... yesterday was my birthday, today is the fourth. my wife is BEYOND ticked off that im working on the bronco on my birthday, and now on a holiday haha. But my kids enjoyed the ride to advance with the top off!

[OLDBULL8]

OK well i drive home this morning, around 2.5 hours and when i left the worksite batterys were LH 12.59 RH 12.47. Had the alternator tested at advance on my way. it failed. No load 12.28 and loaded 12.28. But my batterys are both higher than that. and my meter is reading more like 10 or so, hard to tell exactly.

I still say you have a blown diode in that thar alternator. Your meter voltage compared to Advance could be the difference in the meters. You can buy the diode bridge, have to take the Alt apart and check them. There are three positive diodes ( wire is pos) and three negative diodes (wire is neg.). with the meter on ohm scale, you will read a resistance one way, reverse the leads and you should have infinity for good diodes.

[riotwarrior]

Running the engine and testing output of ALT should be 13.5 min to 14.5 max...12.5 not enough...

3G is simple swap...I can help with if you like...WELL worthwhile eliminate the external regulator and so forth so easy, swapping pulleys is a no brainer...easy peasy!

Get ALT tested and if ok replace voltage reg...those are the only two real culprits here that could cause this issue...

One more thing make sure the LARGE charge wire that goes from the ALT to the relay for starter is in good condition and that your fusable link is not shot! mine charged barly becuase a few wires where left in poor condition but there and could charge slow but no load! I'll post pic tomorrow still have that WALL ART wire!