Question about STARTING and Voltage Issue.

[MATTHEW J PALUMBO]

I have a 2009 LTZ Tahoe. Been having an issue that goes like this.

Sometimes vehicle starts just fine no issues, AC runs, ALL electronics are fine.

Sometimes vehicle starts and the voltage stays low, like right near 9 volts lows. When this happens, if I drive the vehicle, whatever causes a drain to the electrical system, AC, Electric fans, etc, the voltage will continue to drop and cause the "check charging system" message to scroll up and battery light to turn on.

IF, I see the voltage is low from start, I can shut the vehicle down and restart once or twice and it will go back to normal. It will run fine after this.

This all started after a dealership did my inspection. It came back with this voltage issue and my rear brakes were jacked as well. (I have not gone back to the dealership due to sheer frustration)

I HAVE, replaced the alternator, the battery and the electric fans (i thought at first the trigger was when the High speed fans turned on for the AC. Additionally I replace the fan control relay and the Fan High Speed relay.

Next steps are going to be checking the ground wires throughout, possibly changing the starter (maybe bad solenoid), and the Mega Fuse on the firewall.

I have verified that the voltage is right, when acting properly and is low when it reads low.

Any other suggestions?

 

[Fless]

Welcome to TYF, Matt.

What type of work was done with the inspection?

Is this a State inspection, or some other required vehicle check?

 

[MATTHEW J PALUMBO]

Welcome to TYF, Matt.

What type of work was done with the inspection?

Is this a State inspection, or some other required vehicle check?

It was just a state inspection.

 

[avalonandl]

Check your battery connections and clean them. Also could be an alternator going bad.

 

[MATTHEW J PALUMBO]

Check your battery connections and clean them. Also could be an alternator going bad.

I replaced the alternator already, that was one of my initial thoughts.. I replaced without test the old one.. not a great move.. but it was a few minute job and a few bucks.

 

[Fless]

Battery cables can rot from the inside out, even though they look good from the outside.

 

[kbuskill]

These trucks have RVC (regulated voltage control). Trace your ground cable from the battery down to the RVC sensor, it is a ring that the ground cable passes through.

Unplug the RVC sensor and see if it fixes your issue. If it does buy a new RVC sensor or just leave it unplugged, no harm will be done.

The RVC was something GM did to try to improve fuel mileage by disabling the alternator when certain conditions are met.

 

[CaptainAmerica1]

Just because a part is new does not mean it isn’t faulty...

 

[Doubeleive]

when you get this low voltage thing going on where are you checking the voltage? try checking at the alternator output and then check it again at the battery.

 

[OR VietVet]

Welcome to the forum from Oregon. Read this link: https://www.fixmyoldride.com/Chevro...e7e5cd24ed24635&at_ab=per-2&at_pos=3&at_tot=4


We recommend that you put all your rig(s) info in your signature so we all don’t have to guess at year, make, model, engine size, trans, rear axle locker…….etc. While you may have posted pertinent info in your first post, you may forget to do it again and the info is needed by us anyway. Makes it way easier on all members that attempt to help, to have that info right up front. It is also recommended that you take a pic of your RPO codes, on the inside cover of the glove box, and post that image in your signature. All this info will greatly help those that will try to help with a problem.


If there is any other info, like upgrades, mods or recent mechanical/maintenance work done, that would be helpful in any post as well. Too many times a question is asked by the poster and after about 10 responses we find out that the poster has done recent work to attempt to fix the problem or work that was done that SEEMS not related to the problem.

 

[MATTHEW J PALUMBO]

when you get this low voltage thing going on where are you checking the voltage? try checking at the alternator output and then check it again at the battery.

The voltage is checked at the alternator and battery.

 

[MATTHEW J PALUMBO]

Welcome to the forum from Oregon. Read this link: https://www.fixmyoldride.com/Chevro...e7e5cd24ed24635&at_ab=per-2&at_pos=3&at_tot=4


We recommend that you put all your rig(s) info in your signature so we all don’t have to guess at year, make, model, engine size, trans, rear axle locker…….etc. While you may have posted pertinent info in your first post, you may forget to do it again and the info is needed by us anyway. Makes it way easier on all members that attempt to help, to have that info right up front. It is also recommended that you take a pic of your RPO codes, on the inside cover of the glove box, and post that image in your signature. All this info will greatly help those that will try to help with a problem.


If there is any other info, like upgrades, mods or recent mechanical/maintenance work done, that would be helpful in any post as well. Too many times a question is asked by the poster and after about 10 responses we find out that the poster has done recent work to attempt to fix the problem or work that was done that SEEMS not related to the problem.

What occurred is what was detailed in the post. That is the chain of events. NO WORK done prior to the issue. It was good to go the day before it went in for state inspection, left the dealership drove the 1 mile to my house and parked. The next day is when the issue started. Coincidence.

Great Article. That was my next approach. Ordered new cables and cleaning all the connection points.

 

[Joseph Garcia]

Welcome to the Forum from NH.

You've already received lots of great suggestions from knowledgeable folks here for items to check out. These truck are notorious for electrical issues, when grounds become corroded and are not clean and tight. Generally, the first item that we check are all grounds in the engine compartment, to ensure that they are clean and tight.

Continue to report back on the suggestions above, we we will work with you, until your issue is resolved.

 

[MATTHEW J PALUMBO]

Welcome to the Forum from NH.

You've already received lots of great suggestions from knowledgeable folks here for items to check out. These truck are notorious for electrical issues, when grounds become corroded and are not clean and tight. Generally, the first item that we check are all grounds in the engine compartment, to ensure that they are clean and tight.

Continue to report back on the suggestions above, we we will work with you, until your issue is resolved.

Will do. Waiting til the end of the workday and will be out underneath verifying, cleaning and replacing as needed.

 

[MATTHEW J PALUMBO]

OK. Removed ground. Cleaned all contact points and connectors. Reassembled and happy to report success. I dont have the new cable to replace with yet, waiting for delivery. Also noticed another improvement, no fluctuation in the blower fan while the AC is running and I am coming to a stop.

Thanks for the great info and appreciate the assist!

 

[OR VietVet]

Vehicles in rust belt areas have this problem more than the rest of us. Glad it is now fixed.