Electrical issues - where would you start?

[alrock]

Okay, so my H3 has had alternator whine through the stereo for the past several weeks. Stock stereo, unmodifiied, but sounds like a poorly set up aftermarket stereo. I've got a 2 year old AGM battery and batteries typically last 2 years here in the desert though AGM ones can last longer. I'm on the original alternator (2007, 183,000 miles) and the terminals and connections are tight.

So, a new symptom came up. Started up the H3 Saturday morning and loud pops came through the speakers and kept on going as I drove. The radio reset and XM disappeared - I could not reach it cycling through the bands. Within a half mile the Stab Sys and ABS lights came on. I stopped the truck, turned it off, waited a few and restarted it. It was a slow crank but it restarted. All of the above electrical symptoms remained except that XM came back.

That was on my way to the airport (went home and swapped vehicles) so when I got home last night I unlocked the H3 with the fob. It did unlock, but the interior lights faded away in the next few seconds. There wasn't even enough juice left to lock the doors. I had to put a jump pack on to lock the H3.

So, where would you start? It's losing juice so that could be battery, alternator or a short, right?

Thankfully the H3 hasn't needed any work in 2 months/1200 miles since the trans needed new solenoids and the propshaft needed a u-joint and a CV :roll:

 

[Roastbeast]

Check the battery terminals make sure they are clean and tight. Also could be a bad battery

 

[JPaul]

Sounds like a bad ground. Could also be a bad alternator. But usually when dealing with radios and getting alternator whine it's due to insufficient or bad grounding. With it losing power that quickly I would disconnect the alternator to see if you stop getting the drain. If it does then pull the alternator completely and have it tested. Probably needs to be replaced.

 

[Bowser-II]

I’ll second the alternator, failure modes can look like weird electrical issues, battery problems, non charging of the battery, etc.

I would look at the main electrical contacts as well to be sure the contacts are solid and tight and that there is no corrosion indicating current flow.


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[08H3]

Use a Scangauge or other OBD scanner where you can read the voltage. When my alternator went out, it was very clear when the truck was running on the alternator and when it was on battery alone. I don't think that will give you a definitive answer by itself, but it may help point you in the right direction. Also, I had no unusual lights other than the alternator warning, until the very last moment when the engine shut off and I found myself praying I could coast to the next driveway...in the dark with no headights. At that point every light on the instrument panel freaked out.

Hope you get it sorted out quickly.

 

[4speedfunk]

If you can get it started...take the positive terminal off the battery while it’s running. A properly functioning alternator will keep the car running. If the motor dies, pull the alternator and get it tested.

 

[Mr_Rich]

First off I would check voltage at the battery with a voltmeter. Turn on the different accessories like radio, heater (switch positions 1-4),wipers, and headlights to load the system and see what kind of voltage your carrying. I've made a voltmeter a standard tool to carry with all the vehicles I own. I learned that lesson the hard way. Back in the old days a capacitor (or condenser as it was also called) was used to control radio static. There's probably a similar circuit that controls the static in our newer vehicles.
I should probably add that I also get alternator whine in my '98 Firebird that I keep stored these days. The last time I started it up the battery was about 11.8 DCV and the alt. whined until the battery started charging with positive voltage. It's very dependable otherwise; I just don't drive it enough.

 

[Jeepwalker]

I had a 90's GM truck that did pretty much the same thing (incl the popping). I put up with it for a few years actually (even though I was pretty sure it was the alternator), eventually the Alt failed. I replaced it and all those radio issues went away. Inside the alternator of my truck are diodes and some other electrical parts. It could be such a thing that one of your diodes is failing. Or the brushes could be wearing (and sparking). Or some other issue, perhaps not alternator related. If you don't want to give up your Original alternator, take it to an Alternator/Starter shop and have them rebuild it. The parts are not very expensive at all (you can buy them online too), but they have labor into it. Usually costs about the same as a rebuilt alternator from a parts store, maybe a little more maybe a little less depending on what it needs. It usually takes them about 5 min to break it down and tell you what it needs. I'm convinced OEM alternators are higher quality than rebuilds. How many rebuilds last 200k miles? (or 20,000 for that matter?)

That was on an older GM pickup, your issue may be different than mine was. If you do some internet searches for radio buzzing you get a lot of info. It's not an uncommon issue. Let us know what it ultimately turns out to be.

 

[alrock]

Swapped the battery today. Batteries Plus had a special for 20% car batteries with online orders. Got a Duracell AGM made by East Penn.

Truck was dead before the swap. Put on a jump pack, waited sixty seconds, tried to start it. Dead, and radio would not even light up. Moved the jump pack connectors a bit and the radio lit up and the truck started right away. I pulled off the positive terminal as it was running as 4speed recommended and it continued to run.

While the battery had a good charge (as tested by Batteries Plus) I think there were broken internal components. That's common in AZ as batteries break down in the heat and as I mentioned before, they last about 2 years.

Not sure that I'm finished - maybe the alternator has intermittent issues or something else is still there. But step 1 of troubleshooting is complete. Hope that's the last step.