97 5.7L Z71 Alt/Batt Question

I've got a 97 1500 Z71 with a 5.7L. Anyway, couple weeks ago it started going from a little over 14 on the amps down to 11 on my cluster and then it would go back to 14 within a few minutes back and forth back and forth so I went to Oreillys and they said my alt. was bad but they checked it while it was doing it so I bought another one and put it on and it does the same thing so I pulled my alt. and batt. off took them in Oreillys and load test them both and they show to be good. I've checked my cables and my frame grounds and everything seems to be good. While it was at 11 volts I used a jumper wire from my batter ground to my frame to check my ground conn. and it didn't help. I also swapped batteries just to feed my curiosity and it still does it. I'm at a loss on what to do now. Any ideas?

Belt slippage? What is the condition of your serpentine belt and your automatic tensioner?

I would be half tempted to get some sort of cigarette lighter plug and connect it to a voltmeter to just leave connected while the truck is being driven so when the guage shows it acting up, you can glance at the voltmeter to see if the guage is accurate or if its lying to you.

Its accurate Blake, I've used my multimeter to check volts while it was acting up. When swapping the alt. I had to use the tensioner and it seemed like it was fine, I do notice the belt is kinda weaving back and forth on the pulleys though. I don't think thats a problem but Ill do some more checking tomorrow to make sure. I never thought of that. Thanks

Hmmmm head scratcher.....

Is it possible you have two bad alternators? You could take the alternator in and have it load tested.

Otherwise the voltage regulator is incorporated in alternators now. The PCM does control the sense voltage going to the alternator, so its possible you have a bad connection or a faulty PCM.

Blake, I did have it load tested and it showed good.

Here's a new head scratcher. I bought the truck 1 month ago and I used the after market remote start a couple days later and it made my starter hang in for about 10 seconds, since then I never got it to repeat it until today. It seems the only time it does hang in is when my voltage is low. I used it 3 or 4 times in a row tonight while the volts were low and it hung in everytime. :confused:

What brand remote starter, and who installed it? The voltage problem could be your remote starter shorting out....

You could be right. Not sure who installed it cause it was on the truck when I bought it. The brand is Ultra. I was having problems a week ago with it not unlocking but it would always lock. I took it to a friend of mine that has a Home/Car Audio store here in town and he replaced a relay for the unlock. Works fine now but my factory key FOBS always work. I actually talked to him about pulling it all out. He said he would do it for $20 which is reasonable but I hate to lose the remote start even tho I only use it just to see if it works. I don't need it cause my truck is always in my shop. That might be the way to go Mr. Blake. I appreciate your input.

Ultra starters are actually pretty good. I have installed 2 of them. Both times it was a 1250 model with lock unlock and start. I have never had issues with them. So your problem could have something to do with the installation.

If I were in your shoes, I may just go in there and just simply unplug the remote starter for a week. There are two main harnesses that go to the brain of the ultra starter. Make sure at the very least you unplug the large connector with the 6 thick wires going to it.

I'm almost wondering if either the starter itself is shorting out internally or if the install is shorting out causing one of your main B+ ignition wires to ground out causing a large load on your battery and charging system.

Sucks you are having problems. I actually just bought my pickup not long ago too, and was thinking about installing a remote start with keyless entry. My issue is mine doesn't have factory keyless, so it would be better to install a remote starter with keyless than just keyless alone. It is just so darn cold in MN right now to be messing with anything on your vehicle. If only I had a heated garage...... I already have the RS unit ready to go. I was able to track down an old unused code alarm ca-520 with keyless and start. I just don't like the looks of the new remotes (like baby toys), plus 90% of everything nowadays comes with an aftermarket alarm which if installed is just opening up a whole other can of worms.

I agree with you, I'm not a big fan of mine though. Its the alarm, keyless,and remote start.

I will unhook it like you said tomorrow if I can and see if that changes anything. I should know within a day cause it does it all the time. Thanks alot man, you've helped me more than I could tell you.

No problem. Them things are never good if they arent installed right. I've never been a fan of the ones with built in alarms. Just more problems, plus interfacing them with factory alarms is always a pain in the @$$.

I agree with you, I'm not a big fan of mine though. Its the alarm, keyless,and remote start.

I will unhook it like you said tomorrow if I can and see if that changes anything. I should know within a day cause it does it all the time. Thanks alot man, you've helped me more than I could tell you.


the alternator wiring may be the problem...........the connector at the rear need be clean no green on connectors..then the red wire check the fuseable link to the battery...

Last 2 days it never charged at all so I had no choice but to pull the alt. and take it in to be load tested again and this time it tested bad. Installed the new one and so far so good. Ill see what happens tomorrow.

Last 2 days it never charged at all so I had no choice but to pull the alt. and take it in to be load tested again and this time it tested bad. Installed the new one and so far so good. Ill see what happens tomorrow.

you probably had bad brushes...I have had alternators stop charging then give them a hit to get home...brushes if you can do it and find a place that has the parts is about 25.OO....I got 380,ooo out of my 1983 alternator,,,with one brush change out at 225,ooomi...