Dead Alternator = wild engine revving and other elect oddities

[Miescha]

So my TLC has been "resting" for a few years while I've been busy (nice to see the forum still active

On a few recent drives, I noticed the alarm (aftermarket CodeAlarm) would occasionally sound after starting the truck and I would hit the fob button to deactivate it. After a few more drives, it started happening WHILE I was driving (my kids call this the Ethiopian Landcruiser sound - as it seemed to happen a lot during a recent trip to Ethiopia . . . and they all thought it was cool and wanted to leave it .

Not surprisingly, the last attempted drive found me with a dead battery. It occurred to me the aftermarket alarm has a feature which activates it if battery power is disconnected (I'm reminded of this when my ear is next to the siren whenever I'm changing a battery . . . ). No big deal, switched to the secondary battery to 'jump start' myself and pulled the main to charge on the bench for testing. The pattern repeated with the secondary winch battery and ultimately, I learned that the secondary was indeed DEAD (2-yr old Optima blue) and the main is fine (identical 2-year old Optima Blue).

Next drive was a bit longer (maybe 15 miles) mostly highway and no problems with the fully charged main back in place. But when I started the truck to head home, it started fine and then freaked out. The engine was revving from idle to ~2,000 rpm back and forth (continuous surging) and half the dash lit up. I shut it down, started it back up and everything was back to normal, but a few miles into the drive it returned (dash lit up like christmas and engine surging). I drove it home avoiding stop lights (surging revealed the need for front brake pads soon and parked it. Checked the battery and it was at 11.73 volts. After a lot more thinking, a few days of IH8MUD forum researching, I concluded that the alternator was toast. I also decided I was too busy (pronounced 'lazy') to fight the Sequoia alternator into place, so I went about pulling the old original alternator for testing.

This thread has all the links needed for someone just starting the journey:
https://forum.ih8mud.com/threads/another-150a-alternator-and-wiring-upgrade.608585

After taking my alternator to several parts stores, I learned that it is dead as possible. In fact, all three tests show as FAILED (Lamp/Diode, regulator, and Rectifier). But I'm left wondering, what the heck caused the entire Alt to fail? Why would a bad alternator cause the engine revving issue?

Other oddities also occurred that now seem to make sense . . .

1. the power windows were super slow (they have been for a while and I have a set of window rubber sitting in the house for years waiting to be installed)
2. the power seats seemed really slow (I figured I just got fatter in the years the cruiser sat, and I probably need to order some new while gear thingies . . . and lose weight)
3. the aftermarket stereo would occasionally turn off while driving
4. the wipers seemed really slow (I figured really old blades with hard / dry rubber)

But . . . the headlights and dash lights all seemed bright as ever.

So am I missing another issue I should check while sourcing a new alternator? Rebuilding the original seems out - I was up for ordering brushes, but with the diode and regulator also gone ...

As always, TIA.

 

[LINUS]

When my voltage regulator went out, my 1FZ hunted to find its' way to idle, similar to what the brainbox does to re-learn after you leave the 80 dead for extended time.

If it helps any, our local battery store that just sells batteries - won't sell you an Optima without you ordering it specifically & taking their "heckling seesion" for a bit. I experienced it myself when my Op died & asked for a replacement, production moved somewhere that it impacted quality, their recomended battery (and what I took) - is an Oddessey (sp) brand. It was a few $$ if you were buying outright (I was partially in a warranty cover), and it was VERY heavy, quite a bit over the outgoing Optima.

I guess it's hard to find a good thing to say about Optima now, according to that store (they been in business as long as I can remember too, must be doing something right).

 

[Miescha]

Thanks for the response Linus. I'd been off the forums for a while when the last two Optimas were replaced, and the previous Optima batteries lasted ~7 years. But have since followed Cary's excellent battery thread here:
https://forum.ih8mud.com/threads/battery-information.610857/

and agree that the overall consensus is that Optima quality has significantly declined since moving production to Mexico. It looks like two Northstar batteries are in my future ... but I need to sort out the current problem and make sure it is purely the alternator before throwing more money at it

 

[Tools R Us]

Low voltage can cause the things that you are experiencing. Maybe not all of them, but testing with low voltage will not be productive, fix the alt/battery problem and see what you have.

 

[stinky]

Just had the same thing happen to me the other day. Load tested the battery and found it had dropped a cell. New battery and checked alternator output. All ok. Problem solved.
Cheers, Mike.