Chevy Electrical Puzzle

[Tessie]

I have a 2001 Chevy Express 3500 that seems to have a pretty big phantom draw to the point of draining a brand new battery overnight. A friend suggested that the problem might be the crap GM stock radio because they have two hot wires one of which can suck power even when the ignition is off. I replaced the radio. Net result? The battery goes dead in two days instead of one. Grrrr. I am not able to do my own wrenching, unfortunately.

I have am appointment with a Chevy dealership in two days to try to fix this. Another friend mentioned that a relay to the fuel pump can get stuck open, hence the drain. I don't hear anything from around the fuel tank after I turn it off.

The vehicle is an ex fleet vehicle, has only 118,000 miles, seemed to be in pretty good shape, otherwise....runs well, fluids clean etc. 

Any other ideas as to what it might be,? Possible fixes or work arounds?  I will be leaving to hit the road pretty soon hopefully, and driving it every day, plus have a good jumper battery. Suggestions from all you wise mechanics out there?  :huh:

 

[Dennis]

You may notice this one but I'll mention it anyway. Brake light switch gone bad letting brake lights stay on.

 

[HalfShadows]

Hi Tessie, sorry about your dilemma. Electrical problems can be a real pain in the Arse. The best advice I can give is to follow up on your appointment. I hope you get a mechanic that is good at troubleshooting - especially electrical. Troubleshooting from a distance, one can only speculate with limited info. Good Luck.

 

[HalfShadows]

P.S. If anything electrical was added or parasitic to your stock electrical system during the van build. Inform the mechanic, chances are one of the non stock components is the culprit. It may help during his/her process. I know that is where I would start.

 

[Tessie]

I did the build myself and aside from installing non polarized LED rv lights, I didn't mess with the electrical system, although I would like to get a Stinger installed to hook up to my house batteries. My mechanic tested everything and said it was all fine. I have gotten the impression he just doesn't want to be bothered.


I haven't hooked up my solar yet. Still in the process of installing all the components.

 

[bullfrog]

First off disconnecting the battery will keep you from running the battery down which you only get to do so many times before it goes bad. Having a high quality cut off switch installed might be more convient and is a good theft prevention measure. While the battery cable is off put a 12 volt test light between the battery post and the detached cable end. One at a time pull a fuse and see if the light dims. If it dims then there is something in that circuit that is using battery power. The more it dims the more of your battery power it is using. This should give you or your mechanic an idea of where to look. Things like clocks should make the light barely come on but a brake light will make it shine brightly.

 

[Vonbrown]

with a voltmeter connected to the ground battery post and the disconnected ground cable, you will get a voltage reading, now, pull fuses one at a time until the voltage reading goes away. that circuit will be your drain.

 

[highdesertranger]

Vonbrown and bullfrog just gave 2 easy ways to find the drain. sounds like your mechanic is a yahoo or they just have no interest in working on it, which if this is the case they should tell you. highdesertranger

 

[Tessie]

I'm leaning towards the yahoo factor, personally. He waffled on giving me an appointment for this week which is why I called the dealership. Didn't like the vibes he was giving off either, like how dare I bother him. Don't think I will be gracing his establishment with anymore business. 

Thank you for your advice, everyone, it is much appreciated. You give me too much credit in the fixing department. I'm a 60 something , petite grandma with some general knowledge about a lot of things, and am pretty handy usually, but my electrical skills are pretty rudimentary. I can follow a diagram to hook things up, but that's about it. I have no clue how to use a voltimeter, know the fuses might be located under the dash or maybe on the firewall. I would rather take the easy way out and let someone who actually knows what the heck they are doing, tackle this. Heck, I have to climb up on a step ladder to even be able to see anything under the hood. 

But thanks to you all, I can at least ask more intelligent questions.

 

[Tessie]

As it turns out, according to the dealership, it's the alternator, which they generously offered to change over for me to the tune of $750.00. Ahhh, nope! The local, well recommended mechanic can do it for half that. If that doesn't do it, next is a battery cut off switch.

Thanks for the advice everyone.

 

[highdesertranger]

Dang what is that a solid gold alternator? highdesertranger

 

[bullfrog]

I have bought whole cars with good alternators for that.

 

[highdesertranger]

exactly. highdesertranger

 

[Tessie]

My guess is that they saw me as naïve, perhaps a bit dim, and willing to pay big bucks to be "rescued". Nope. Not your typical old lady here. As my Irish friends put it "I didin't come down in the last shower of rain."

 

[jonyjoe303]

if the dealership said its the alternator or maybe cutoff switch? I would get my own voltmeter and check the battery terminals when the engine is running, it should read 14.4 volts, if it does its good. 
And since you been driving it all over the place, it looks like alternator is good. It only doesnt want to start when it sits for a while. To me it points to a loose battery terminal cable, loose connection somewhere that is preventing the battery from getting a full charge. If battery not getting a full charge the symptom would be bad battery or weak alternator but it can be a 5 dollar battery terminal.
I had similar problem with my astrovan for years, and replace several batteries, but it was a battery sidepost terminal that wasnt screwing down all the way. Easy fix. Get a second opinion from someone else. 750, even half that is too much to spend, the dealership they won't always do a better job troubleshooting then a local mechanic.

 

[MrNoodly]

The alternator is an easy, profitable answer for the dealer, but not necessarily THE answer. Or it might be only a partial answer.

 

[B and C]

The internal diodes of the alternator can go bad and cause a drain on the battery. A local mechanic should be able to replace the diode packs for far less. If it is indeed still putting out voltage, I would suspect one of the three diode packs in the alternator. Easy enough to check once you have them out.

 

[MrNoodly]

...750, even half that is too much to spend...

First of all, dealers mark up the price of parts at least 100%. I've experienced independent mechanics who then jack up the full dealer price another 100% or more. Then dealers and most independent mechanics charge a book rate for labor. The book might say two hours to change an alternator when it actually takes a slow mechanic a half hour. I understand all this mark up. They have overhead to cover. But sometimes (often?) it goes beyond that.

Long ago, there used to be a reason to get service from the dealer. They were the only ones who had the parts and, supposedly they were most familiar with the quirks of their vehicles. But that's not true anymore.

That's why I love Ernie in Ajo, Arizona. He say to order the parts online, like from Rock Auto, in order to save yourself a pile of cash, then he'll install them. And he only charges for his actual time. But he has a unique attitude and business model. He says, "I'm busy enough. I make enough money. And it's a small town so I can't get away with screwing my customers."

 

[highdesertranger]

yep a bad diode will cause a drain on a battery and the alternator might still charge normally. it's actually more common then most people think. most mechanics don't want to change the diode pack so they just say the alternators bad. highdesertranger

 

[Jackpine]

The battery itself could be bad also. If you don't know how old the battery is look for a date code on it. Batteries typically last 5 years but can go bad in months or last 8 years or so. I just bought a battery at Home Depot for my car with a 40 month warranty for $90. That's $20-80 less than other places near me wanted for a 36 month battery.