6.5 rd with low alt voltage.

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Chevysrule454

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98 2500 6.5 td with dual batteries. Both batteries test good individually.
Cant get more then 13 volts on volt gauge fully charged running. Cleaned all posts and still only 13 volts. Consequently my headlights are p*ss yellow. Swapped over the highbeams over to Sylvania ultra blue .....better!.... but still very dull. Alternator replaced with an oem replacement 1.5 years ago.
Any help?
 

Tom P

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Check and clean all of your grounds...all of them, and then check them again. I ran a charging system test on my truck last weekend because the starter has a difficult time turning the engine over. My grounding system is junk. The main negative cable has been spliced at least once and has a cheapo fix a cable end on it. When I did the test, it said my alternator was shot and my battery was toast. Played with the ground cables a little bit and got some positive results. Bad ground issues are common with older trucks, and these trucks seem to be notorious. Never trust these gauges implicitly.
 

eyesi

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90 halfton and Tom P i agree, Chevysrule454, trust in a multimeter instead dash gauge, very common issue in trucks like your. Also, if your batteries are fully charged, your alternator will show less voltaje, because not much charge is demanded from him., low bright at your headlamps can be their ground connection and also dirty contacts at light swich connector and inside proper switch, but also in relative circuits

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Z71Hobbs

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I also have a 6.5...clean your grounds (cheap and easy to do)!! Better yet, get a could new ground cables off of each battery.
 

michael hurd

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98 2500 6.5 td with dual batteries. Both batteries test good individually.
Cant get more then 13 volts on volt gauge fully charged running. Cleaned all posts and still only 13 volts. Consequently my headlights are p*ss yellow. Swapped over the highbeams over to Sylvania ultra blue .....better!.... but still very dull. Alternator replaced with an oem replacement 1.5 years ago.
Any help?

Volt gauge in dash can read whatever you want, the needles can be pried off and put on in a different 'clock' position.

Verify voltage at the alternator, from charge stud to alternator case.

As far as headlights go, these trucks typically have ~11.2V at the headlight terminals, to fix, disable the DRL's and install relays and larger wire to the lamps. Simply pulling the fuse will disable them.

Read the chart:

http://www.danielsternlighting.com/tech/relays/relays.html

Ultra blue lights are junk.

http://www.danielsternlighting.com/tech/bulbs/blue/good/good.html

If you truly want to 'see' in the dark, you need full voltage at the bulbs and good ( new ) OEM housings, HIR 9011 / 9012 bulbs ( not HID, HIR stands for Halogen Infared Reflecting )


Yes, the OEM headlight pricing will suck. Most aftermarket housings are junk, pure unadulterated junk. Bunk adjusters, light radiation patterns that are not legal conforming or safe for oncoming traffic.

If your budget is tight, clean the lenses ( polish ), disable DRL's and install relays, larger wire and plugs. Even with 'old bulbs' it will give you a lot more light on the road.

Once you can afford it, buy GM ( Vosla ) bulbs for the housings. 9011 and 9012 to install in place of the 9005 and 9006. They are electrically and optically compatible with the housings.

The key on the bulbs will require very slight modification to install in 9005 / 9006 positions. There are many tutorials on the internet on how to do this.
 

Eskimomann209

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As far as headlights go, these trucks typically have ~11.2V at the headlight terminals, to fix, disable the DRL's and install relays and larger wire to the lamps. Simply pulling the fuse will disable them.

This is good
But be advised the parking brake will no longer disable the lights

Also when I reccomemded this to people
I got my **** jumped because a so called electrician said that it was bad if the lights were getting power from your relay and the operator turned the lights on with the switch. His problem was that the lamps got voltage from two "sources "
 
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98 2500 6.5 td with dual batteries. Both batteries test good individually.
Cant get more then 13 volts on volt gauge fully charged running. Cleaned all posts and still only 13 volts. Consequently my headlights are p*ss yellow. Swapped over the highbeams over to Sylvania ultra blue .....better!.... but still very dull. Alternator replaced with an oem replacement 1.5 years ago.
Any help?


Check your instrument panel fuse ("Guages" #4 ? in the d-side i.p.) A blown fuse knocks out charging completely but one with excessive resistance will cause low charging voltage (verified with a multimeter at the battery terminals) High resistance between the fuse and the ecu as well as in the positive feed will also wreak havoc; should have battery voltage there with the engine off, key in run. Did you check your battery terminals for good connections? And again, like another poster said, those headlight buckets suck when they get old and hazy. Dump the blue bulbs and replace the buckets with new eagle eyes off eBay at the very least, OEM if you don't mind the cost.
 
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