Alternator issues or ??? (1 Viewer)

[REZARF]

So I have a dual battery system with a Red top starter and Yellow Top Optima 2nd battery connected via a Blue Sea 7622 ACR.

The other day I was out driving and my red battery light on the dash came on. My ScanGauge said I was running at 11.6V-11.8V while driving. I combined both batteries while driving home and the charge didn't drop below 11.6v but usually it remains around 14v while driving around town. When I got home both batteries read 12.5 and 12.8 respectively... a little low for the yellow top.

I am assuming this is the alternator starting to go?

Is there any way to isolate the alternator and check it's health?

99 Cruiser with 342k miles so it's likely due.

 

[TheForger]

I'd say it's either the alternator as a whole or the voltage regulator within the alternator

 

[CBeckFJ]

Alternator or voltage regulator. The yellow Optima that came with my truck had the same issue, because of the alternator. Simple swap, can be pulled out from underneath after moving the power steering pump.

 

[REZARF]

One other thing to note is my driving lights weren't coming on nor did my Scan Gauge fire up. Is there a way to check a voltage regualtor... or a way to identify it under the hood

 

[hoser]

The voltage regulator is built into the alternator on these vehicles. If you want to upgrade to a 130A (03'+), now is the time. It will require a different connector, which you should replace anyway as it often crumbles upon removal.

 

[abuck99]

One other thing to note is my driving lights weren't coming on nor did my Scan Gauge fire up. Is there a way to check a voltage regualtor... or a way to identify it under the hood

First check battery voltage engine off - 12.5,12.6 or greater is good. Then while engine is running take multimeter and get a voltage reading at pos and neg terminals, anything under 13v (or over 14.5) is failing alt- could be brushes and those are $25 to replace- worth trying that.

Fwiw just had an alternator go out last week. Besides battery/charging system light being on, noticed that the Scanguage wouldn't auto on when engine was running I had to manually turn it on and then could watch charging voltage steadily drop to low 12’s.

 

[REZARF]

The voltage regulator is built into the alternator on these vehicles. If you want to upgrade to a 130A (03'+), now is the time. It will require a different connector, which you should replace anyway as it often crumbles upon removal.

thanks hoser, is the connector easy to splice into the 99 harness or is it major surgery? Thanks!

 

[REZARF]

First check battery voltage engine off - 12.5,12.6 or greater is good. Then while engine is running take multimeter and get a voltage reading at pos and neg terminals, anything under 13v (or over 14.5) is failing alt- could be brushes and those are $25 to replace- worth trying that.

Fwiw just had an alternator go out last week. Besides battery/charging system light being on, noticed that the Scanguage wouldn't auto on when engine was running I had to manually turn it on and then could watch charging voltage steadily drop to low 12’s.

Thank you for the reply. I’ll give all that a try.

 

[hoser]

thanks hoser, is the connector easy to splice into the 99 harness or is it major surgery? Thanks!

The 98-02 is a three prong connector. The 03+ is a 4-prong square connector. One slot will not be used. The most difficult part is picking at the terminals to try and remove them with low visibility. But you have to do that anyway unless you're splice the wiring.

 

[Cola]

Thank you for the reply. I’ll give all that a try.

You should also check the output on the output spline of the alternator (squeeze an alligator clamp up there for your multimeter (engine off) then start it up and check the output)). I had an alternator i though was dying but the crimped connection on the supply wire where it connected to the alternator was super corroded. Crimped on a new one on clean wire and was good to go. Eventually ran a new power wire but I thought it was a failed alternator... Nope, just 20 year old wiring.

 

[abuck99]

Video on that process about 5min in on this video

 

[REZARF]

Video on that process about 5min in on this video

Thank you fellas, great info!

 

[REZARF]

You should also check the output on the output spline of the alternator (squeeze an alligator clamp up there for your multimeter (engine off) then start it up and check the output)). I had an alternator i though was dying but the crimped connection on the supply wire where it connected to the alternator was super corroded. Crimped on a new one on clean wire and was good to go. Eventually ran a new power wire but I thought it was a failed alternator... Nope, just 20 year old wiring.

Thanks I'll give it a go.

 

[REZARF]

So I have a few options, I could replace my alternator with a factory 100amp or go through the hassle of upgrading to the 130amp '03+ alternator. That includes changing the connector and added expense of some new splices... about $70 bucks all in for the addition of 30amps... plus the hassle of converting it. Is there any real world reason to bump up and go through the hassle of converting for a few more amps?

I am running quite a bit of electrical extras through a dual battery setup with a Blue Sea ML-ACR 7622. My cables are all 1/0. I use the following accessories but never all at once. Primary Red Top, second battery is a Yellow Top if it matters.

• Fridge ARB
• Sub Amp 500w
• HAM 75w
• Lights 150w x 2
• Light bar
• WInch

My factory alternator ran great charging around 14.2v until it gave up the ghost... I have 340k on the Cruiser so things are wearing out with alarming regularity

Just not sure if I need the extra amps, or if converting the connector is actually a hassle? Maybe its easy but it doesn't look like a pleasant space to try to convert a plug from the oval to the square connector in such a confined space. Buying the splices opens up the ability to cut and paste, but I'd prefer to drop in a replacement if the 100amps is enough juice?

 

[calskibum]

Hi Everyone,

I apologize if I'm sidetracking this thread, but I have a related question. I've noticed that recently, when I'm stopped at a red light with AC on high due to the 100 degree weather here, my scan gauge II shows 11.6v to 11.7v. But as soon as I start to drive, the reading is back up to 12.4v or higher. Is this an indication that the my alternator is getting weak and about to die or are those readings normal? I'm assuming that the reading on the scan gauge is for the charging power of the alternator and not the voltage of the battery, correct?

 

[jerryb]

yes, no, yes

 

[calskibum]

Thanks, Jerryb.