IS THIS ELECTRICAL PROBLEM? PLS HELP!!!

[zalez]

Hey everyone!!

Ok i have a 1997 f-350 7.3 power stroke diesel.

The other day i was driving and stopped at a red light , when all of a sudden my battery gauge started to move back and forth at the red light. The truck started to shimmy and shake.All other gauges were fine , only battery gauge was moving back and forth.

When the light turned green, i started to go and turn left when my truck all of a sudden just died. The radio turned off and on right before the truck died.

I waited to cross intersection and let the truck come to a complete stop.

I then turned the key to start and it started right up.

The truck ran good for the next few days.

Well now on saturday it started to do the same thing, it hasn't died completely again , just shaky and battery gauge acting crazy.

symptoms: shaky truck,shimmying, battery gauge goes crazy, when im driving the battery gauge doesnt shake but it stays on battery level really high.(not in middle)

*** i also have 2 new batteries**bough about 1 month ago**

Can someone help or guide e to what might be problem?

Thanks,

Daniel G.

[porkchop6209]

First off Daniel, open the hood, take a deep breath and relax, and carefully check the battery positive and negative cable terminals to make sure they are nice and tight and free of corrosion. If they pass this first visual, check the condition of your alternator drive belt, make sure it is in good shape, tight and not slipping. If you have an electrical meter check to make sure each battery produces 12.5-12.8 volts sitting with the engine off. Crank the truck and let it idle two minutes, you have to wait for the glow plug relay to cycle off before the PCM will field the alternator and let it charge. With no electrical accessories engaged, on a diesel, you won't see a quick spike in the voltage output of the alt. It should rise to around 13.2-13.8 volts, then load the system by turning on the lights, wipers, heater blower, and 4-way flashers; you should see the voltage drop back then start to climb. Have someone accelerate the idle to 1,500-2,000 rpm. The voltage should climb to 14.5-14.8 volts and level off. If you don't know how to check amperage, or current, output run it by an AutoZone, O'Reillys, Advance, etc. and get them to load test the charging system. If it doesn't produce 30-85 amps output, depending on load, then the inside of the alternator is likely wearing out and it needs to be replaced. If all of this checks out you need to check the integrity of any/all electrical grounds, preferably with the negative cables disconnected from the batteries. You don't want to go pulling electrical connectors with the batteries hooked up, you can cause major problems doing that. Always disconnect the negatives first, then the positives; hook up the positives first and the negatives last.
If you can't isolate a problem in this area, check to see if your glow plug relay has burned the contacts and is sticking together. You really need a good mechanic to do that, and it's a 20 dollar part so it might be just as efficient to simply go ahead and replace it, with the batteries DISCONNECTED. Don't blow yourself up and cause more problems than you started with. Get yourself a Chilton's manual, they have good illustrations to help you through the procedures. The important thing to do is take your time, think about what you are doing and trying to accomplish and don't go off chasing "bunny trails", if you get frustrated, stop and take a breather and come back with a fresh perspective.

[zalez]

hey porkchop6209,

thanks for your reply!! I did a meter test myself today and it all tested fine.with a meter reader.

12.5 with the truck turned off and 14.5 with the truck turned on.

I was still skeptical so i ran by Oreilys and had them tested.

"Bad" alternator is what their machine said. And also bad batteries even though i just got them about a month ago.

I also took to advanced auto part and they to tested it and it also read "bad" alternator.

I was able to purchase the alternator and installed it myself, took about 15 minutes to replace it. Easiest alternator ive ever replaced!!!

I also took the old one and oreily tested it in their machine where it actually
runs it and it "FAILED" the test.

So i guess it was the alternator, it running fine now, ill drive it a few days and let ya'll now the final outcome.

Thanks!!!!!!!!!!!

[porkchop6209]

That's great news, I hope it works out that it was the only problem. And good for you for fixing it yourself. Always happy to share anything I've learned over the years. Gotta get a lot better educated on PSD's myself, this site has been a real lifesaver. Let us know how it holds up for you.