Hey guys the other morning I was driving my truck and I noticed my batery gauge was all over the place. I had a big draw going on I believe but It seemed to drop while sitting. I have the old 2G alternator so im sure thats part of the problem but what im wondering is if I go 3G do I have to get an addapter like the ones that rjm sell? I have a fuse and can do that part but the part that goes on the alternator do I need to buy?

Second question If I go to a cheaper alternator thats for my truck a 90 amp will I still be at risk for it having issues like the old ones did?

 

DON'T jump to conclusions about the alternator being bad and, furthermore, DON'T run off and buy a replacement! Simple diagnostic tests can determine the problem. Just because the alternator is old does not mean that it's bad.

Start by checking the charge rate at the battery. With the truck running, touch the test leads of a multi-meter [set to DC voltage] to the battery terminals. If the reading is any less than 14 volts, remove the alternator and take it to your local auto parts store to have it tested and confirm that it's bad. If it is bad, then you can replace it.

Unless you're planning on installing some extra electrical accessories [such as serious stereo equipment and extra lights], you won't need to upgrade to a 3G alternator. Just get the replacement recommended by your parts store OR, if you can stand to let the truck sit for a couple of days, look into having the existing alternator rebuilt. Generally speaking, a rebuild is more expensive, but it depends on a lot of variables.

Now, whether you keep the existing alternator or replace it, if the volt gauge is still going berserk, you need to look at the gauge itself and determine if it's a bad ground or shorted circuit. You'll need to remove the gauge cluster so you can perform ground and continuity checks on the wiring harness that hooks into the gauge cluster. Unfortunately I don't have that information, but if you have a service manual, it should include a wiring diagram. Or you can contact Subford- he's got a lot of diagrams available.

Good luck and keep us updated.

 

First, paying attention to your gauge is a good idea, it tips off trouble before it gets real bad, sometimes! Not familiar with the 2G, 3G things you mention, but I can tell you this: Going to a higher capacity alternator (say, from 90 amps to 120 amps) can mean trouble unless you upgrade the main wires connecting the alternator to the battery.

Unless you have add-ons requiring huge amounts of power over and above the requirements imposed by the truck's original equipment (like rows of K-C Lights!), a bigger capacity alternator will never be called upon to provide it's biggest output, unless the battery turns up near-dead sometime.

impish

 

Impish was spot on about the wires, you need not only the 3G alternator to do the swap, but upgraded cables. If you do a junkyard hunt you can get the proper 3G with all the wiring conected to it and replace that fire-prone 2G, it's quite easy and cheap. Do a search on the site, there is a lot of info regarding this upgrade.

Anyway, it isn't a bad idea to check all the grounds and clean the battery terminals.

 

I have looked into the 3G already and since it seems my 75 amp alternator under a load is not cutting it I was thinking replacing it before it fails me. I have a sub and amp off my stereo, upgraded my headlight harness and when I have my lights on stereo on wipers the needle is all over the place that's why I was going to upgrade

 

Check the brushes. Probably worn out. They may have cut into the slip rings as well.

 

The connector that plugs into the alternator is the culprit for the fire hazard. The poor design is why it will not charge at low engine RPM.

Knowing the history of these fire hazards I highly suggest you check the big connector ASAP. Perhaps your symptoms are a sign of a fire waiting to happen.

Remember this thread: https://www.ford-trucks.com/forums/1...ator-fire.html

 

Honestly with all the problems with the 2G alternators you need to unplug the power connector from the rear and inspect it. It will be the one with the 2 black wires coming out. If it even looks or smells slightly burnt you need to replace it or do the 3G upgrade. Below is a link to a GREAT thread on the 3G upgrade. In the 20 years I have owned mine I had 3 2G alternators burst into flames under the hood on hot texas summer days. Read the thread below and make your own decision.


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

 

Thanks guys I'm going to pull the plug and see what it looks like then see how much I'm going to have to spend to do the upgrade

 

My bet is if you do the research and buy a good JY alternator you can get away around 50-75 bucks. Before you decide to do the upgrade read the ENTIRE thread I linked above and make a decision good for you.

 

It is a most serious issue, to heed these guys' advice regarding fire! To begin with, everything underhood is hot most of the time: this degrades both the metal connections within the connectors, and the plastic parts themselves, then add to it the heat generated by electric current passing through connections. The wiring itself is usually heavy enough to not overheat, assuming non-factory high-juice add-ons have not been made, but anyplace where a connection is made a problem lies waiting to develop.

There are lots of big black burned spots on the pavement along our Interstates, each representing a burned vehicle. I saw a big motorhome burn between Phoenix & Tucson on I-10 once; all that was left sitting there were half-melted metal parts, the tires even burned off the rims!

impish

 

I have been wanting to do the 3G upgrade for some time but I fifgured I had more time but with winter coming and having to drive home with my lights and if its snowing or raining add the wippers Id hate to find the alternator fail on me