Live Help - Voltage Drop while stopped, nearly stalls - on Cross Country Road Trip (1 Viewer)

[suprarx7nut]

Hey all, sorry for the thread as I'm sure this has been covered. I'm a thousand miles from home, short on time and without a PC, so my search ability is limited. I'm hoping somebody might have a suggestion for a common problem like mine on this chassis.

My Cruiser had a sudden problem tonight. Coming to a stop it nearly stalled and all electronics turned off, then back on, headlights dimmed and voltage read around 10v on the stock gauge. As soon as I touched the gas it came back to life and all was well.

It did this a couple more times when coming to a stop. Changing into neutral fixes it. Touching the gas fixes it.

I had the alternator tested at O'Reilly's using their handheld tester on the battery and all tested good.

Using my Bluetooth OBD2 scanner I watched obd2 voltage and it sits around 12.5 while driving, dropping to about 12.1 at idle. I wasn't able to witness a dimming/near stall with the scanner so im not sure exactly how low it gets when it has an "episode".

99 LC, 236k miles, unknown alternator age, die hard platinum group 31 AGM battery that's 18 months old, a stereo amp for a sub and otherwise all factory electronics.

Any ideas? I have a lot of driving in town, Denver, CO, in the next few days, then a 950 mile trip back home to Phoenix this weekend. A break down would be really inconvenient...

Thanks!

-Andy

***Update:
Issue appears to be fully resolved. Alternator was found faulty after a test at Sears and was replaced.

Voltage while driving is now 12.8 or 12.9 via my bluetooth OBD2 adapter. The alternator seems like the culprit. I think the low voltage after leaving the Sears where it was replaced was just due to the battery needing to charge back up. After many hours of driving in the last couple of days (~1000 miles) it's nice and stable and the voltage dips are gone.

The O'Reilley false pass really threw me for a loop on this. My first thought when the voltage dipped was that the alternator was going out. I quickly dropped my wife off and hit the local parts store. Their tester said all was well and I started chasing other leads and started this thread. If the O'Reilley tester could have found the fault I would have bought an alternator and replaced it myself in the street/parking lot and saved the $260 in labor from Sears. Oh well.

So as a PSA to everyone else... Don't necessarily rely on the handheld alternator tests!

 

[DirtDawg]

It sounds like you have a bad battery. While running at high rpms, the alternator supplies enough power to run the vehicle, but when those rpms lower, there isn't enough power to run. Have you given a visual inspection of the battery yet? When having the alternator tested at O'rileys, did they load test your battery?

But first I would check all connections and fuses at the battery. Then give the battery a once over. But honestly sounds like your battery is maintaining little to no charge. Strange on an 18 mo old battery though.

 

[suprarx7nut]

It sounds like you have a bad battery. While running at high rpms, the alternator supplies enough power to run the vehicle, but when those rpms lower, there isn't enough power to run. Have you given a visual inspection of the battery yet? When having the alternator tested at O'rileys, did they load test your battery?

But first I would check all connections and fuses at the battery. Then give the battery a once over. But honestly sounds like your battery is maintaining little to no charge. Strange on an 18 mo old battery though.

The alternator check was quick, I'm not sure they load tested it. He connected it, let it settle, got three "passed" results and said all was well. It was 2 minutes to closing so I was just happy he took the time to test it at all.

I'll see if i can get it tested tomorrow. I'll also check connections more thoroughly too.

 

[Ninja Cruiser100]

Bad battery.

 

[TexasCrane]

There's a long history of issues with the diehard platinum group 31 batteries. The alternator can't supply enough voltage to properly charge that battery. This is apparently why Sears is no longer carrying them.

Most people seem to be killing them within about 2 years which fits right in with your timeline.

 

[Lowbudgetlc100]

have you tried removing the battery terminal while the truck is running? are the terminal post clean?

 

[suprarx7nut]

@TexasCrane interesting. I'd never heard that. Sears did indicate that battery was discontinued along with all platinum AGM batteries.

Update: I had the battery tested at Sears and it passed the on vehicle test today. I didn't have time to let them load test it, but I'll try to do that tomorrow.

All connections looks perfect that I can see. Battery posts are great. Zero corrosion, just dusty.

I'm still stumped.

It starts great, just as powerful as ever. In driving for a few hours today with a dozen trips it's only gone weird once and quickly came back to life.

So strange...

 

[2001LC]

Does sound like battery, post are greased aren't they.

 

[suprarx7nut]

Does sound like battery, post are greased aren't they.

I don't think I used any dielectric grease when I put this battery in. The posts look very dry and clean.

 

[2001LC]

That could be your problem. Without grease post will build a lite gray coating that prevent full charge & discharge. White lithium is best but even Vaseline will do. Clean and grease posts and clamps.

I'm south end of Denver near the DTC area (Arapaho Rd & I25). If you need some help stop by, I'll fix you up. Just PM me.

Note: Batteries can develop a condition from lack of charge that takes a few charging cycles to correct.

 

[2001LC]

It was OP statement of 12.5 and less that made me think battery. If not for that I'd have been thinking fuel/air issue, spark or possible TPS.

It's always best to start with the simplest, once cleaned & greased keep in mind what @TexasCrane said ^ about the diehard platinum. I'm not familiar with that condition, I'd consider that next if condition persist. You should get ~13.2 -14.8 V charging after a couple of charging cycle if not right away.

While under the hood this morning take a look at Drive belt & tensioner.

Not to plug Wal-Mart, but the one battery I purchased from them was about 5 years ago. I doubt it will last the winter, but I'm happy as it was only a 3 year warrantee battery.

 

[re_guderian]

18 months is not bad for a Phoenix battery. I just killed an Interstate in 12. The heat is hard on batteries. You might want to pick up one of those LiIon jump start batteries (Costco carries them) for your trip home. They're small and easy, and work great if you get stranded with a dead battery. Even if you get a new battery in Denver, they're handy to have in the truck.

 

[TexasCrane]

@TexasCrane interesting. I'd never heard that. Sears did indicate that battery was discontinued along with all platinum AGM batteries.

This post elaborates on some of the issues: Sears Diehard Platinum 31M issues - Expedition Portal

The bottom line is that you need an alternator that's putting out 14.7v to properly charge that battery fully which virtually no vehicle alternator is going to provide.

 

[suprarx7nut]

Thanks for all the replies guys. Texas crane, that is done awesome info on the dhp 31.

I just dropped the car off with Sears to test the battery and the alternator. The clerk was absolutely adamant it was the alternator at fault after I described my situation. I had to politely argue for a solid 5-10 minutes to convince them to test the battery to hold a charge of the car. If nothing else i guess their testing could top off the battery charge.

We'll see what results come back.

 

[RootMeanSqr]

In addition to checking connections at the battery, be sure to check chassis ground connections as well.

Hopefully it's just another case of failed DHP 31.

 

[suprarx7nut]

Verdict is in....

Alternator.

Putting out 11.08 V apparently. Having it replaced now.

I guess this means the handheld testers at O'Reilly's aren't worth a whole lot.

I'll update if this seems to have solved the issue. On my way to Sears today i was seeing 13.0v when I started the car and 12.6 by the time I arrived 20 mins later.

 

[suprarx7nut]

The drive home from Sears was not reassuring. Voltage on the obd2 scanner was the same or worse than before (12.0-12.9). With the headlights on, stopped, in drive, with brake applied it dips to 11.8 or so.

It hasn't stumbled like it did before so maybe it is fixed and the obd2 voltage is just always low. I haven't talked it before this week.

I'll continue to update. I'm about out of diagnostic time now as the rest of my time in Denver is booked solid before we head home. Here's to hoping it's resolved!

As a side note, being a diy mechanic and paying $240 in labor for an alternator swap hurts me deeply! Haha.

 

[camino70]

I'd go get your old alternator, it probably wasn't bad. I'm still leaning toward a battery.

 

[Ninja Cruiser100]

I'd be pissed. I would wager that you alternator was fine.

 

[suprarx7nut]

I'd go get your old alternator, it probably wasn't bad. I'm still leaning toward a battery.

I'd be pissed. I would wager that you alternator was fine.

Yeah, this evening will provide some good time to test for any existing problem. If it persists I'll be at Sears tomorrow morning at open demanding an alrernator swap back to my old one and a refund on the labor. If the problem is gone... Maybe it was the alternator.