# alternator not charging at high rpms



## cincy snowdog (Dec 19, 2005)

c 70 with a 8.2 shows fine on idle but it drops at higher rpms when turning on heat or others ,goes to eleven or so.when turn all off it ok but can have all on and it showing fine when at idle, what do you think?cables ,batteries(TWO)or alt.


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## snowbankr (Oct 6, 2004)

just went through something similar with my '94 2500..was the ground strap from frame to motor and the small ground wire on the neg. terminal that goes to the inner fender. Cleaned them up, rewired, put liquid tape on the repairs and now all appears OK. Check the wires first, then test the output of the altenator(s) with a voltage meter. It's simple stuff like this that really gets me when it's my equipment when its down. Sometimes we are too close to the forest to see the trees.


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## earnies2 (Feb 20, 2003)

I would start at the belt the only variable is the rpms at idle it can handle the load but at higher it looses voltage... check the belt and tensioner...if that dosent solve the problem take the alt off the truck and have it tested it might have a bad diod or rectifier remember to always check your batterys and cables first......


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