So I have a 2000 blazer that is temperamental with charging. I've done all the obvious stuff. I.e alternator, battery, cleaned the grounds. Still no luck. When I start the truck cold(first start of the day) it charges the battery. But if I shut if off after that it won't charge it and will keep the amp gauge around 11-12. Sometimes when I start the truck it will show 11-12 amps then shoot up to 14 after a few minutes driving it. I have no idea what's not working correctly and would love some help. Thanks in advance.

 

Dont go by the gauge, when the truck is running, take a DMM (digital multimeter) and put it on the positive post of the battery, then ground it to a bolt on the body (not the negative on the battery) and see what the reading is, have someone go in the truck, and check it at 1000, 1500, and 2000rpm.
Could be something screwy with your gauge?

 

Yeah the stock gauges are a bit tempermental at best.