[magicc8ball]

Over the past couple of weeks I have noticed that after I start my truck the voltage will hover around 12.4-11.9. This goes for at least 30 seconds and as long as 2-3 minutes. I can kill the truck and start it right back up and the volatge still hovers around 12.4 and below.

2 weeks ago I had to replace my optima yellow tops (under warranty, whew) and that is when I started noticing this problem.

I can let it sit at idle or drive it around and it will eventually climb up to 14.0-14.4. What could be causing this? I have searched the web and the forums for a couple of days and cant find anything. Could someone
help me in finding a starting point for this?

 

[RT]

Its caused because the glow plug relay has 8 little power hungry glow plugs activated for up to 120 seconds after you turn the key. Until that point, the voltage will hover exactly where yours is. After the glow plug relay is switched off, the voltage pops up to normal charging voltage. Perfectly normal.

 

[newmans11]

make sure all your battery conections are clean and tight, the next thing i would do is have your alternator tested at drivers battery and directly off the alternator itself, ive seen where a few alternators take 5 minutes or so before they start putting out, ive only seen 2 that did this but they both went out within a week

 

[magicc8ball]

I thought it might have something to do with the GP's but when I saw it take 2-3 minutes I was not so sure that was right.

The alternator has already been replaced prior to me owning it. Not sure when it was replaced but it it has at least 70k on it.

Thanks RT and Newmans11 for you replies. As of now I take it that it is acting as it should.

 

[Alaskapsdvan]

Have the alt tested as I have had one go bad in a short time or miles.
A bad alt could leave you stranded some place.

 

[mouseys_7.3]

Your alternator is fine, as RT said its the glow plugs. Those suckers draw something like a 100 amps(some one cite me if I am wrong). The factory alternator is 130 amps(per orielys). Mine Auto-meter gauge reads 12 exactly and when the glow plugs disengage it spikes to 13.9 then the second alt is turned on and it stays around 14.3 to 14.5.

 

[magicc8ball]

So while on my way home tonight and the past couple of days my battery light will flash once maybe 2 times and the stay off. It happened tonight and I have the scan gauge in my truck and started monitoring the volts. they never got above 13.8 which usually it sits at around 14.1-14.4. I had my lights and radio on everything else was off. I turned on the A/C and put if on high and it dropped to 13.3. the lowest it got was 12.8...

Got home let it idle and it was pushing 13.3-13.8 this was with lights radio and ac being turned off and then on.

I disconnected the batteries and it dropped to about 12.8 and as low as 10.4 for a split second.

Do these alternators have the regulator built in or are they separate? if separate where is it? Do you guys think this is a regulator or an alternator? I really do not want to buy another 110amp cheapo alternator... I was thinking of getting nations alternator. I am leaving in the morning for the deer lease so I need to figure this out asap. I can borrow my brothers alternator for the time being as we are replacing his transmission so it is not going anywhere anytime soon haha...

 

[RT]

It likely is the regulator. Here's a popular upgrade that won't break the bank - http://www.thedieselstop.com/forums/f25/inexpensive-upgrade-140-amp-large-case-alternator-295912/

 

[magicc8ball]

Well I put on my brothers alternator and took mine to get tested and it passed with flying colors. While my brothers alternator was on I was having the same voltage fluctuation. When driving with the lights and heater on full blast I had 14 as the high and 13 as the low. the 13 came in while at idle at a light or stop sign.

I did notice that when I turned my brights on at idle the volts went up and was steady at 14. I do have fog lights and running lights on the truck. When the brights go on the fog lights shut off and my volts go up.

After my drive I opened the hood put my meter on the output of the GPR and it was at 0. I tested the AIH relay and the output was putting out 14 volts. I did not think this was supposed to be pushing power if the engine was warm? I do not have the AIH installed it is removed and I have my boost terminating there.

I will delete just trying to figure out the best/easiest way.

The last thing is I did not have these issues until I replace my glow plugs a couple of weeks ago. I do know that not all the glow plugs were heating up before the change. so it was never pulling the max amount it could have.

 

[RT]

I suggest removing and cleaning every battery connection- both ends. Bad grounds can do whacky things to your system.