My 1992 Ford F150 2g alternator caught fire last week and thought my truck was going to go up in smoke. Turned out I was able to stop the fire after I pulled the power wires from the alternator because it was the connector that was on fire, not actually the alternator. I did some searching on the net and in addition to this forum I found that this is a common problem for the 2g alternators. Although I don't have any extras in my truck (all stock), I didn't want to by the 2g alternator again fearing a fire might occur again a few years down the road. Not knowing how to upgrade I read up on it and gave it a try and am posting this just in case someone ends up in the same boat as I was and might need to upgrade their 1992 Ford F150 4.9L 2g alternator to a 3g alternator.

After removing my 2g alternator I removed the alternator power harness including the 2 black wires and 1 yellow wire but kept the green/red wire that is for the alternator gauge. I purchased a 3g combo repair plug at the following:

Part # 925606 Ford Repair Plug Combo for 3G Series Alternators

With the above connector you see the yellow wire is no longer necessary, it gets power from the alternator power post. The white wire connector connects to the alternator "Stator" post and the green/red wire connects to the green/red wire that was left behind.

Then I purchased an alternator cable kit at the following:

RJM Injection Tech — Alternator Charge Cable Kit

I installed the mega fuse holder on an 8"x8" L shaped bracket I attached to another bracket that holds one of the emission canisters near the battery and starter solenoid. The side of the bracket that was connected to the canister bracket had to be shortened before installing. I bought the L shaped bracket at home depot, I'm sure most hardware stores have something similar. Then I cut the 4 gauge cables to size soldered on the connectors (easy to do with a propane torch) and put one cable between the hot side of the starter solenoid and one side of the mega fuse. The other cable (not yet installed) connects between the other side of the mega fuse and the alternator power post. These wires replace the black wires previously removed from the harness.

Next I purchased a 95amp stock 3g alternator for a 1992 E150 4.9L at the following:

Part No. 20225112, Replaces: Ford F2UU-10300-EA, Lester 7755

I went with this alternator because I didn't need a high output alternator, it has the same mounting points as the original alternator and has the same size pulley so I don't have the change the belt. It also has an acceptable plug clock position that is similar to the original. The only problem with this alternator is that it accepts a smaller top bolt than the original. I just drilled and tapped it for the old bolt (3/8" x 16 thread). Get the proper size bolt and you won't need to modify a new alternator if you have to get another down the road.

Before I installed the new alternator I had to shape the connector on the cable so that it would fit the power post of the alternator. I used a dremel for this which was quite easy.

Finally I installed the alternator. The yellow wire with ring terminal was placed on the power post of the alternator then the 4 gauge cable with slightly shaped connector was placed on the power post and the nut tightened to hold them in place. Then the gray connector attached to the white wire of the combo connector is connected to the stator terminal on the alternator. Plug in the combo connector re-attach the belt and its done.

I am not endorsing in any way, the stores that I bought my supplies from above. I only put the links in because I cannot attach photos.

I hope this helps anyone who doesn't have the experience like I don't. It wasn't difficult to do so anyone who has reasonable mechanical skills should easily complete this job.

 

Those 2G alternators are truly a fire hazard. I recently replaced the 2G on my 1992 F350 with a 3G from RJM. I used their wiring kit and also purchased a 160+ amp alternator from them. All I can say is WOW, what a difference. Ryan has some great products (no drilling or tapping required) and it works like a charm.

Glad to see your truck survived the fire and you chose the wise path to upgrade to a 1000X better product like the 3G.

Welcome to FTE!!

 

I'm really glad this forum exists. This thread's a little old but I'm hoping to get someone's attention.

Friday, I had the day off from work and I replaced the oil pump in my 300 and that was not exactly my idea of an ideal Friday. Before dropping the pan and pump I checked my rockers and rods to make sure they were OK. Reused the 1 year old valve cover gasket once more than I should have and had a leak. Sunday morning I replace the gasket and get everything back together and run her in the driveway for around 20 minutes and notice a small coolant leak from my transmission cooler line right at the connector on the top of the radiator (right near the alternator). Swell. Must have developed when I pushed the lines out of the way to drop the pan. No big deal, radiator doesn't owe me anything, it's 20 years old.

So, I have the truck idling in the driveway... I run into the basement to put a few tools away.. I come out and my truck is smoking the whole neighborhood out. Alternator is on fire.

I immediately flip my lid, run back into the basement, leaping over obstacles like the most graceful gazelle you've ever seen (I'm 255lbs).. Grab the fire extinguisher, blast the crap out of my alternator ... and the fire does not go out. At that point, I feel that my beloved truck is in peril and I go into freak-out mode. I finally got my brain together and run to my cap's toolbox, get my tool kit out and disconnect the battery. I hit it once more with the powder and it finally went out. Luckily the only damage is to the alternator and the bottom connector - not sure what the proper name for the connector is.

Connector on the bottom of the alternator is gone and is now a nice plastic puddle in the driveway. Naturally I thought that I was up the creek and had to buy an entirely new wiring harness. I found that to be unacceptable and off to the Ford-Trucks forum I went.

Initially I thought the connector shorted out because coolant got on it but then I thought about how many times I'd been in puddles up to my rocker panels or deeper and got water on the alternator... Never happened before. Then I thought that I got oil on it and it burnt up but I really don't think I got any oil on it whatsoever. After reading about this 2G alternator blowing up, I imagine I'm just another victim... At least my alternator waited 20 years but it didn't need to go out in this little blaze of glory... that's for sure. I would have been content with it dying on the side of the road and calling one of my AAA friends even though pride would have taken a hit (never been towed in 20 years). I'm just really glad this thing caught fire in my driveway with a fire extinguisher available and not at the supermarket. I would have lost my truck. I will never drive another vehicle without a fire extinguisher onboard.

This write up looks perfect and I will be going with this solution as I am not willing to put the same type of alternator back on my truck. I just wanted to share my experience and thank the original poster for taking the time to post it.

I do have a question, though. Just wondering if this kit replaces that bottom connector that melted away on me? With my luck, that's the one that doesn't get replaced... Hopefully someone can tell me otherwise.


Thanks,
Mike

 

That connector is long gone when you upgrade to a 3G.

 

Yes, you'll be getting rid of both quick-connectors. Here's another link w/ pics which may be helpful.... Converting A Ford 2G to 3G Alternator

A couple related questions of my own...
What actually fails on the 2G alternators and why? My truck has a recently replaced (rebuilt) alternator, but it's just a stock 2G. I'm just wondering what urgency level I should have on doing the 3G swap. I'd like to think that a "new" alternator would be much less prone to failure, but I don't know how true that actually is (or isn't).

Lastly, since we need the larger frame alternator, it's typically the 3.8 Taurus that we are directed to as a donor (if going the junkyard route). Is the '92+ E150/F150 a better choice for some reason? Oddly, I don't even recall reading that it could even be a donor.

 

If im not mistaken its the plug that is a fault. I think it has something to do with shorting or overloading but im not sure. All I know is my fire hazard is gone...

 

Bingo! You are correct.

More info from Steve83: Steve83 2G vs. 3G connectors

 

That helped me to do some more digging - here's the details as provided in TSB 96214, as it applies to F150 through F350, model years 1986 through 1994 (as well as numerous other cars).

ISSUE:
When a generator fails, there are a few failure modes that may cause heat to be produced at the wiring harness-to-generator connector. This excess heat may damage the female terminals on the wiring harness, resulting in increased resistance. The increased resistance produces more heat. When the generator is replaced, the resistance produced by a damaged connector may damage the new generator and could result in a repeat repair, including installation of another generator. High resistance (caused by a damaged connector) will not go away until the damaged connector is replaced.

ACTION:
Visually inspect the harness-to-generator connector for damage (heat, corrosion, distortion and cracking) before installing a new generator. Install the Generator Wiring Harness Connector Kit (E5AZ-14305-AA) if the harness-to-generator connector is damaged.

The Generator Wiring Harness Connector Kit (E5AZ-14305-AA) contains the following:

^ One (1) Red Wire Butt Connector
^ Two (2) Yellow Wire Butt Connectors
^ One (1) Wire Connector Assembly
^ One (1) Instruction Sheet (I.S. 6849)

 

Yes to the connector going bad. Apparently it degrades to a point where it screws the resistance up and overheats and then - pop - no warning. I love my truck but some engineer screwed up real bad on that part.

To RLA2005, DPDISXR4Ti & Evan_P - thanks for the good info on the alternator and the connectors. I'm glad to know that this won't be much of a P.I.T.A.

I'm also bewildered as to how it went 20 years before happening. In all honesty, I think it happened because I yelled at my truck when I was changing the oil pump.... LOL.

I read that TSB yesterday after trolling the forums and finding this thread.

Unfortunately, as of 2007 Ford has discontinued that product and it is very hard to find. I read on a Lincoln forum that when the connector was first discontinued, Ford raised the price to over 180.00. Cheaper to buy a new 3G and maybe even all of the wiring. My first thought was to go to the bone yard and see if I can grab a 3G and harness off of a 1996 F-Series truck but the more I think about it, I would just rather wire in all new stuff and ditch the connectors. I don't want to worry about wires overheating because of butt splices.

Anyway, I'm glad this thread has woken up once again. Lots of good info here. I've come to learn that F series owners are some the most resourceful people on the planet.

 

Most reman alternators come with a new connector .
That being said the 3G is the way to go

 

If you read (and believe) the TSB, it's the alternator that fails first, which then degrades the quick-connector contacts as it fails. Thus, depending on whether any damage was done to the connector, replacing (only) the 2G alternator may or may not put you in a better place. Do you feel lucky, punk?

You're going to have the same number of butt-splices regardless of whether you use new parts and junkyard clips. And when you consider that the clipped-off connectors will likely come along for free with the alternator, it ends up being a pretty good deal (especially if you find a "low mileage" alternator).

BTW, one alternative to using the Mega fuse is to grab the twin-lead fused-link wire as used on mid-90's Explorers. It's a little different way to wire things up, but an easier plug-n-play solution.

 

Read this thread:
https://www.ford-trucks.com/forums/1...doing-one.html

 

Just be wary of the comments (incorrectly) indicating that you need the 7" 3g for the 4.9. What you need is the 8.25" one.

Am I correct that the 3G didn't show up on the 4.9, as stock, until the final year of production in '96? Did it use the 8.25"? Just thinking out loud, maybe it used the 7" for that one year, hence the conflicting statements on this topic?

 

Get a 8.25" ear spacing 3G for the 4.9. It goes in like this:

 

I have a friend with a '95. I inspected it last night to get an idea of how it is wired. It is definitely a 3G. I'll be going back there tomorrow and while I'm there I'm going to measure it just to be sure. I will confirm the size once I find out..

Thanks for the pic, Evan_P. Looks to be exactly what you posted. I think I have the same bracket in my '92 but I'm not 100% - nothing I can't modify if need be. If it is the same size I'm just going to hit a local parts store and grab the alternator for a '95 rather than get one online. At least I won't have to deal with shipping hassles if it is defective. After looking over his alternator setup, looks to be a breeze to rewire.