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Electrical issue plusating dash lights

1K views 6 replies 4 participants last post by  Gator5713 
#1 ·
Hi have 99 and alternator shows charging properly, but lights on dash and headlights when at a stop will dim a little get brighter and does this continually until you start to move and everything is fine until you slow down again, needle on alt. goes up and down slightly also, any ideas?
 
#2 ·
Don't go by gauge in truck, test the alternator with a tester.
DENNIS
 
#3 ·
Alternators on diesel don't put out full power at idle. So some dimming can be expected but it's typically minimal enough to be barely noticeable if at all.
Check your alternator, charge and load test each battery individually. Check and clean ALL connections. Look for the tell tale water line on the firewall above inside fuse panel. Make sure ALL ground connections are clean and tight..
Let us know what you find.
 
#5 ·
Actually, that sounds high for idling!
 
#6 ·
You have to disconnect the batteries from each other when checking with a meter. Any difference between the two of .3 VDC or more, indicates the lower voltage battery could have a bad cell. The real way to check is for Hg, (specific gravity) in each cell. Not possible that way with maintenance free batteries tho.
 
#7 ·
Load tester.
 
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