The problem is not always a cold solder joint!!!!!!!!!! I encountered that problem first hand last year. DUDE check your alternator belt! If the belt is weak or loose it will cause the guages to go haywire, If it breaks like mine finally did while I was still looking for a cold solder joint you will see. I drove my car home about 25-30 mi just on the battery after my belt came off. There was no doubt that the belt was the problem About 3/4 of the way home when the battery was really low the guages were really going nutz,just before the head lights started to dim,anyhow the car ran all the way to my driveway were I coasted into my parking spot. I replaced the alternator belt that day and have not had a guage problem since. So before you check into anything else check the belts. PEACE OUT!!!!!!!!!!