Engine/Transmission (1998.5 - 2002) Apparently a dead Alternator and other woes

[tmacc]

While driving yesterday, the 'Check Gages' light and chime came on and the gauge for charging was below 0. I made it home w/o a problem, but the batteries are too low to start the truck this morning. I checked the code and P1682 showed up. "Charging System Voltage Too Low" No kidding! This manual sure isn't very helpful sometimes. No info on testing the alternator. Anyone got the scoop on which studs to check once I get the batteries charged?

Thank in advance

Tom



Oh, and just to complete the day. The tail pipe broke in half above the axle. It's a 4" after market. I bought it from a guy who was installing stacks. Is there any way to determine who mfrd. it?

 

[rweis]

There is a thread on optional alternators. I think there is one that is significantly more capable than the OEM. I think there is even one that is water cooled. I do not remember if testing the alternator was in the thread or not. Discount Auto etc says they can test them, but I wonder what is really tested.



A search on "alternator" might turn up the threads.



Bob Weis

 

[Mishkaya]

Don't know if you're interested, but foster truck sells replacement brushes for the alternator for cheap.

LarryB's Dodge starting problems solved here.

They worked for me.

mishkaya

 

[PatD]

tmacc,

know its been a long time since this post of yours but what was up with the alternator? the exact same thing just happened to me but my battery will keep it going. also when I restarted the truck the voltmeter showed normal charging.

thanks if you can help

 

[blacksheepdiesel]

I have put 4 new alternators on my truck in just a little over a year (140,000 mi). Same thing happens, voltmeter dives, "check gauges" light comes on. Recently when this happened I pulled the plug on the back of the alternator and stuck it right back on and I had 14 volts again. I did this three different times over a couple weeks. Finally my new little trick didn't work so I installed the new alternator I was carrying with me as a spare. Then had the one I took off bench tested and it showed fine. The rebuilder shop was finally able to source the plug for the alternator and I now have one but have been unable to install it yet. My thinking is the plug is worn and may have even left a deposit (plastic?) on the pins in the alternator. With 647,000 miles that's a LOT of vibration over time and the plug may simply be worn out not allowing the pins to make good contact. Will install the new plug and the old alternator soon and see what happens.

Godspeed,
Trent

 

[blacksheepdiesel]

UPDATE:

Soldered on the new alternator plug and installed the alternator that previously wouldn't charge on BlackSheep and it works perfectly. Leaving tomorrow on a one week 4600+ mile round trip to CA so it will definitely get tested as to whether the new plug solved the problem for good.

Godspeed,
Trent

 

[tmacc]

Hey Guys,

Well I did not think to check any connections, but did check out put and it appeared dead. Went to NAPA and bought their "Lifetime" alternator for about $220, installed it and all is good in the world..... well ,except for a slight drive line vibration. Replaced two u-joints on the drive shaft which reduced it some, but it looks like the 3rd one is worn too. It doesn't feel worn, but neither did the middle one and the vibration reduced some when I replaced it. 216K Gotta expect this stuff I guess.

 

[blacksheepdiesel]

NEW UPDATE:

Have returned from a 4700 mi trip and the new alt plug in the previously "dead" alt worked perfectly.

Note: having the alternator tested for output while mounted and wired to the truck when the truck voltmeter shows no voltage is a waste of time in my opinion. Reason is the ECM controls the regulating of the alt and when the ECM thinks the alt is dead it quits trying to charge, thus testing the alt while still in the truck is fruitless. If you can find a replacement plug for the back of the alt and then put 12 volts to the correct pin (don't know which one) then the alt can be tested while mounted in the truck because you are bypassing the ECM regulator.

Godspeed,
Trent

 

[Boondocker]

Thanks to blacksheepdiesel for illuminating my problem.



I dredged up this post in my effort to diagnose a no-charging problem. Unfortunately, my early research lead me to believe the alternator was at fault because I was getting no charging voltage at the PCM - where the red and black wires are separated by the 140 amp alternator fuse (which I also replaced for good measure).



Long story short - the culprit was the 2-wire plug on the back of the alternator. I didn't notice it was bad when I removed the stock alternator - I even looked. After buying an AutoLife reman alternator, with a lifetime guarantee but no refund policy, I still had no charging, so continued my research on TDR, which led to this thread and further inspection of said plug. Sure enough, one of the wires was broken away, right at the plug, so no chance for repair. I did try to repair it with the help of a work buddy who does electronic wiring harnesses. Even with dental tools and a lighted microscope, we couldn't get the pins out. So I bought a new one for $40 at the dealer, at least it was next day delivery.



The new plug come as a kit with the pins and rubber seals installed on 4 pieces of wire (different colors than the original). Why 4? Spares I guess. From there it's just a matter of mating the old wires to the new wires. I made careful note of the orientation first, then soldered and covered them nicely. It works! Hurray. I bought my old alternator back from the store for the core charge of $45.



Moral of story - Have old part tested if possible before buying a new part. This would have saved me $175 for a remanufactured alternator that I didn't need. So now I have an old spare.



Other moral of story - Had I wimped out and taken it to the dealer to fix a no-charging problem, they surely would sold me a bundle of parts, diagnosis, and labor and taken a week or more for the privilege. TDR saved me that much bacon and I learned some tech about my truck in the process.



P. S. In case you hadn't gathered it from previous posts, that "plug" serves to tell the PCM that the voltage output of the alternator is in spec. If not, the PCM protects the system by keeping the bad charge away.

 

[blacksheepdiesel]

Hey Boondocker!

Glad you got it fixed without spending too much money! That plug and the terminals it fits on are way too small in my opinion. Happy am I that my charging trials and tribulations could be of assistance to someone like yourself, exactly the reason I posted it.

Your truck is set up very similar to mine, wish I had sticks like yours though!

Godspeed,
Trent

 

[John - K5AWO]

Hey Boondocker,

Don't be feeling like you are all alone. My son had my truck out in California. Called me one day and said the alternator was dead. We did some trouble shooting by "remote control" with me trying to figure out what was going on while still here at home.

I also ended up with an "old spare alternator" that works just fine.

The problem in my case was a blown fuse in the output wire from the alternator to the battery.

Pretty expensive fuse that was. Only $220 from NAPA

 

[TRichmond]

Plug on Alternator?

The back of my alt. has the bat cable and field wiring in a black bolt on block. Seems to me if I remove the field wiring and put negative to ground and battery to plus and check volts. Output checking does nothing if you only have 11. 89 volts. will this work to ck. volts?

98. 5 24 valve 2500 4x4 120000 miles. Auto and club cab and 8 ft. bed. 2nd owner.

Thanks