Engine/Transmission (1998.5 - 2002) WIERD alternator/charging problem!

[blacksheepdiesel]

Hey Guys & Gals,



Once upon a time the "check guages" light came on on my '01 and the voltmeter had drops to nothing. Get home, check the drive belt and all battery connections. Start the engine, charges for 3-4 minutes then WHAM, voltmeter drops to nothing again. Took the alternator off, had it bench tested at reputable local rebuilder that rebuilds starters and alternators only. Tests perfect on bench. Put it back on truck, repeat of above. Start tracing down wires, ground connections, pcm tests. No codes shown on Smarty. Take the truck to the same rebuilder and they hook up a known good battery and bypass the electronic voltage regulator, wiring, everything. Alternator will not charge. Put alternator back on test bench, tests perfect. Put back on truck, repeats above. The rebuilder gave me a new alternator told me to try it. YES, the new one works and the voltmeter reads 14 volts!!! Only thing we can figure is there is something loose in the alternator that is vibrated enough by the engine or by the rpm's turned which won't let it charge but does not show up on the bench test.



BTW, this alternator has right at 110,000 mi on it and is 1. 5 years old. The rebuilder is going to try and get me 100% warranty from his supplier!!



Godspeed,

Trent

 

[DCMille290]

Hey Trent,

Did you ever solve this problem?

Yesterday, my volt gauge was just making it to the first White mark above 8 volts. So I waited and drove 5 miles to home, and it never came up, warm here so no grid heater issue.

The really strange thing was I noticed is my Pyro gauge bouncing up to 1000, and back to 300 while idiling in my drive, each time it went up, the "check gauges light" and tone sounded.

The batteries are about 4 months old, cables and grounds good. So I put the chager on the truck over night. Any feedback woul be appreciated.



Is it possible to replace the brushes on these Denso alternators?



Thank you,

David Miller

 

[blacksheepdiesel]

David,

Yep, the problem was something internal in the alternator that would show perfect operation on the bench but on the truck could not get anything out of it. The rebuilder thinks there was something in the stator or windings that would not make good contact when on the truck because of vibration from the engine or simply the rpm's it turned at idle compared to the slower rpm's on the test bench.

My suggestion is take the truck to a local rebuilder and let them test it off the truck and/or on the truck to see if it is good (the electronics can be bypassed when on the truck to make sure the alt is putting out; if it is then it points to pcm internal voltage regulator, wiring, grounds, etc. ). Or if you have a buddy with the same alt swap his on your truck to see if it charges.

Let me know what you find.

Godspeed,
Trent

 

[LOtero]

same exact thing happend to me, i have been trying to troubleshoot it, i also have been getting a issue where my tach drops to 0 and it seems to run in like a limp mode. will only make 20 psi, no smoke and lopes at idle. cycle the key and everything works again

 

[DCMille290]

Hey Trent,

Thanks for the update. I guess with 200,000 miles on the original, it may be time to replace it. I'll keep everyone posted as to what I find out.



David Miller

 

[LOtero]

did you find out anything??

 

[DCMille290]

Just an update, still nothing found as to this issue, truck has been working normaly so I don't know. Tough to troubleshoot when it behaves.



David

 

[LOtero]

yea i know what you mean, mine has been behaving. i did get the no tach low power lopey thing the other day though

 

[bflood]

I'm searching the forums with a simular alternator problem. Mine works fine except on hot days and running the A/C (right, just when you need it), and it quits (so I loose the A/C as well). It seems to be temperature related. I suspect a solid state component in the alternator is breaking down in the heat. Its been doing this for a long time. I guess I'll just have to get a new alternator unless I can find an easy fix.

 

[bigredblur]

I'm not sure this is an "easy" fix but I saw this link the other day while searching the forums.

DODGE DIESEL VACUUM PUMP REPAIRING /TRANSMISSIONS REPAIR