I was checking my voltage at the lighter with a Fluke 87v (with a double banana plug on one end with a lighter adapter on the other) and while driving on the highway I was only seeing 6v DC and 12.6 mV AC. The key has to be on to check voltage with the engine off but I haven't checked that yet. I know I should be seeing more than 6v while driving but no battery light coming on. What am I doing wrong?

You check voltage at the battery or alternator not your accessory socket.anything over 13.0 volts should be ok,if you want to load test your charging system just turn on all your electrical loads and make sure you still got at least 13 volts at the terminals.

Shut off the car. What is the voltage?

With the Negative on the chassis and positive on positive batt terminal?

I thought that the lighter was able to tell correct voltage. I made the little device that connects to the Fluke meter on one side and lighter on the other. My alternator is making some noise (the original one) and I will be looking at the output voltage this weekend but the noise sounds like a bearing so the output looks to be a moot point. Any recommendations on a brand of alternator?

Oreily auto parts alts have life time warranties

seriously bro .... how $#@&## hard is it to simply turn off the car and read the battery voltage ?

Then I'd suggest turning on the car and reading it again.

At 6 volts your car would have serious issues which is why I think you were reading it wrong.

Aftermarket alternators and starters are notorious for sucking ass. They're all remans, and most of them are shitty remans that weren't really rebuilt in the first place. Take your alternator into a shop and have it rebuilt right, or if you must buy new, buy an OEM Denso.

So I called a local reputable automotive electrical company and they quoted me $99 to rebuild the original alternator which to my surprise was actually cheaper than buying a reman unit from any of the local parts stores. They can rebuild it in a day, just drop it off in the morning and pick it up in the afternoon.

Doc's CS144 alternator upgrade.

Thank you so much for this! Are the stock battery cables up to the task of the current produced from this alternator? I wouldn't be able to upgrade the cables for a while.

Yes.
I ran that for over a year before I did my big three upgrade.

How do you even know you need a new alternator?

There isn't anything stated so far that for sure indicates this.

^^this^^

You are correct and I found that the belt was making the noise. It was a high pitched squeal that I thought was a bearing considering that my 4runner is a 2001 with 180,000 miles on the clock but since the charging voltage checked out ,I figured I would go the easiest/cheapest route first and check the belt and after dressing it with a bar of soap(Irish Spring), the noise went away. The good thing about this thread is the info on the CS144 upgrade. Whenever this alternator really starts to die, I will definitely go with the CS144 upgrade. Thanks for not me! Electrical is not my strong suit.

If all the wiring is correct, and there are no poor connections or corroded terminals, yes the cig lighter will show you a reasonably accurate voltage. That being said if you want to actually TEST the voltage, you need to start at the source and work outward. So start at the battery, as has been mentioned. If the battery voltage is good there, but the cig lighter is only showing 6V, then I would look at the connector for the cig lighter to be sure there is no corrosion, or a loose fitting terminal. Then check to be sure you have a proper ground for it. A bad ground will cause a false reading on any type of cig lighter tester.

The CS144 is a good alternative, as Doc mentioned, if you are looking at upgrading. (very good writeup btw) one thought though, and while I see nothing has actually happened, I would recommend getting a larger gauge alternator cable. At full load of 144A, the small 8 gauge charge cable on the 3rd gen is not technically large enough. While it may not ever run at 144A for long enough to overheat the wire, it COULD. At 144A of charge, the recommended gauge cable is 4 gauge. If you look at the 4th Gen 4Runner/2nd Gen Tacoma, that have the factory 130A alternators (Off-road package), they use 4 gauge on the alternator.