When the 1994 in my sig is at idle the battery gauge shows just barely above the orange caution range, when measured with a volt meter the battery will start at about 12.9 and slowly start decreasing so after idle for a few minutes it will be down at 12.5 or so, measured with Datamaster at idle the voltage shows about 11.3 at idle when i slowly start opening the throttle the voltage will climb slightly to 12.1 at about 2500 rpm but when i get to 4000 rpm the voltage drops significantly to 10.8, watching the battery gauge i also see this happening, at idle it is just out of the caution range, at 2500 rpm it goes up to the middle line of the gauge but over 3500-4000 it drops down into the orange caution range. The car died and didnt want to start for my wife this week 2 times. I replaced the battery and the alternator but the problem is still ongoing, it seems to idle okay but if you drive it at all you run the risk of it just shuting off. Any ideas? I really need to get this running ASAP. Thanks guys

BTW the lower datamaster voltages also match the reading on my HSW microedge display

 

everything in the book points to bad connection, battery or alternator. i would say look for bad connections. clean all connections. check the small L wire at alt. for any issues. also check belt.

 

I removed the ground strap from the battery and cleaned the body and strap with sandpaper, i also removed the pos wire and all the others from the battery block and cleaned all those connections, started the car back up and it was showing 13.29 volts at the battery at idle, i though i had fixed the issues but then i turned the car off and turned it back on and it was back down at 12.2 volts, i tried to turn it off and on a few times but it seems to be at 12.2 volts max at idle, the small wires that goes to the back of the alternator look to be fine as well, belt looks new and tight

 

check to see if the engine block is grounded. should be a ground strap from car frame to engine. go back and recheck to make sure the wires u cleaned are not showing signs of heat or bad conection and see if u missed any.

 

Check output directly at the alternator too, the red wire on the back stud. Should be in the 14 volt range.

 

i have the same prob on my 89. now if the pos wires have green in the wire thats bad right. but is it bad enough to not get any charge. cuzill charge my battery in the morning and go for a drive for like 10 mins and wont even have a click.

 

green wires mean something bad is going on. around here it means u got it wet. replace the wire if u can, if not cut it back till u get to clean wire if pos.

 

i replaced the wire from the alternator to the battery checked output at the alternator, still no luck, no changes

 

let us in on it. what was the reading for the output at the alt?

 

my bad evil beef i didnt mean to move on ur thread ill start another 1