08 Silverado Voltage Guage Drops

[fishbones182]

I have an 08 silverado 5.3. The amp gauge drops to arround 10 volts then will eventually go back to 14 volts its done this as long as i can remember. Is this normal? This dosent seem right to me as all my trucks in the past have stayed right at 14 volts unless the alternator or battery were bad. In the morning the lights in the truck are even dim when you open the door. Ive checked the battery connections and have just had to repalce a one year old battery. Thanks for any help on this.

[nootron69]

I have an 08 silverado 5.3. The amp gauge drops to arround 10 volts then will eventually go back to 14 volts its done this as long as i can remember. Is this normal? This dosent seem right to me as all my trucks in the past have stayed right at 14 volts unless the alternator or battery were bad. In the morning the lights in the truck are even dim when you open the door. Ive checked the battery connections and have just had to repalce a one year old battery. Thanks for any help on this.

 

I have had similar electrical probs in past, here is the link to a thread I posted the other week. My prob hasnt re-occurred since I posted. However, I truly believe the 08's have a prob. Have seen a lot of references on here, and my boss's truck (08 silverado) has had probs too. I don't remember if my voltmeter dropped, but I will keep an eye out. My posted link

[fishbones182]

I have an 08 silverado 5.3. The amp gauge drops to arround 10 volts then will eventually go back to 14 volts its done this as long as i can remember. Is this normal? This dosent seem right to me as all my trucks in the past have stayed right at 14 volts unless the alternator or battery were bad. In the morning the lights in the truck are even dim when you open the door. Ive checked the battery connections and have just had to repalce a one year old battery. Thanks for any help on this.

 

I have had similar electrical probs in past, here is the link to a thread I posted the other week. My prob hasnt re-occurred since I posted. However, I truly believe the 08's have a prob. Have seen a lot of references on here, and my boss's truck (08 silverado) has had probs too. I don't remember if my voltmeter dropped, but I will keep an eye out. My posted link

 

 

 

The volatage guage definatly fluctuates up and down. Its the strangest thing ive had happen to me.

[gmtech4]

your truck is under warranty ,the battery is under warranty ,right? whats the milage?

[Jsdirt]

This has come up before. The needle fluctuates because the field coil in the alternator is ECM controlled, on demand. In other words, the alternator is only working when the battery drops below a certain voltage. Less drag on the motor to boost mileage.

 

I do agree that it needs some fine tuning by GM. I've been in several situation where my wipers were moving so slow that I had to put them on high in a light rain. Once the alt kicks on, they go back to normal. Not worth the .5 mpg savings (probably much less), IMO. Part of the new "green" wave that's making good stuff turn to crap these days.

[fishbones182]

This has come up before. The needle fluctuates because the field coil in the alternator is ECM controlled, on demand. In other words, the alternator is only working when the battery drops below a certain voltage. Less drag on the motor to boost mileage.

 

I do agree that it needs some fine tuning by GM. I've been in several situation where my wipers were moving so slow that I had to put them on high in a light rain. Once the alt kicks on, they go back to normal. Not worth the .5 mpg savings (probably much less), IMO. Part of the new "green" wave that's making good stuff turn to crap these days.

 

 

Yes the truck is under warrenty. The truck has 13k miles on it. They replaced the battery under warrenty and I feel the battery is going bad because they are not deep cycle batteries and shouldnt have the voltage drop way low then charge back up time and time again. The dealer just gave me a run arround on the voltage fluctuating. Personally I dont like it at all and if I were concerned about gas milage i would have not gotten a truck. Im pretty sure we all feel that way.

[okcok]

08 gmc sierra 1500 is doing the same thing...still trying to figure it out..

[LeoS41280]

Some customers may comment that the volt gauge fluctuates between 12 and 14 volts on their 2005-08 full size pickup or utility vehicle. Starting with the 2005 model year, these vehicles are equipped with a Regulated Voltage Control (RVC) system. RVC reduces the targeted output voltage to 12.6-13.1 volts when in Fuel Economy Mode to improve fuel economy.

 

The generator may exit Fuel Economy Mode if additional voltage is required. This causes the voltmeter to fluctuate between 12 and 14 volts (fig. 16), as opposed to non-regulated systems which usually maintain a more consistent reading of 14 volts.

 

 

 

 

This fluctuation with the RVC system is normal system operation. No repairs should be attempted. Refer to the owner manual Section 3 (Instrument Panel) Voltmeter Gage for more information.

 

TIP: Refer to PIT4426 for concerns with keeping a camper or trailer battery properly charged.

[fishbones182]

Some customers may comment that the volt gauge fluctuates between 12 and 14 volts on their 2005-08 full size pickup or utility vehicle. Starting with the 2005 model year, these vehicles are equipped with a Regulated Voltage Control (RVC) system. RVC reduces the targeted output voltage to 12.6-13.1 volts when in Fuel Economy Mode to improve fuel economy.

 

The generator may exit Fuel Economy Mode if additional voltage is required. This causes the voltmeter to fluctuate between 12 and 14 volts (fig. 16), as opposed to non-regulated systems which usually maintain a more consistent reading of 14 volts.

 

 

 

 

This fluctuation with the RVC system is normal system operation. No repairs should be attempted. Refer to the owner manual Section 3 (Instrument Panel) Voltmeter Gage for more information.

 

TIP: Refer to PIT4426 for concerns with keeping a camper or trailer battery properly charged.

 

Ok great so i have pretty much nothing to worry about then. All the new crap on these trucks sure makes me miss my older truck ha ha. Thank you again for the information.

[cbxeric]

There's always the Ford gauges which are glorified idiot lights. I get a kick out of the trans temp gauges in the super duty trucks where I work, you drive a hundred feet and the fluid's hot.

[okcok]

well i guess my battery gauge is ok...i still have to find out whats wrong with my windows,dome lights,and keyless entry..

[4wd]

Yes..You are OK

[chakis24]

ok, what about my truck? this started a week ago. its a 2005 built in 2004 and it has never done this. changed the alternator and its still doing it. methinks its the battery. oh, and it fluctuates between ~13 and 16

[minibike132]

This has come up before. The needle fluctuates because the field coil in the alternator is ECM controlled, on demand. In other words, the alternator is only working when the battery drops below a certain voltage. Less drag on the motor to boost mileage.

 

I do agree that it needs some fine tuning by GM. I've been in several situation where my wipers were moving so slow that I had to put them on high in a light rain. Once the alt kicks on, they go back to normal. Not worth the .5 mpg savings (probably much less), IMO. Part of the new "green" wave that's making good stuff turn to crap these days.

 

 

Yes the truck is under warrenty. The truck has 13k miles on it. They replaced the battery under warrenty and I feel the battery is going bad because they are not deep cycle batteries and shouldnt have the voltage drop way low then charge back up time and time again. The dealer just gave me a run arround on the voltage fluctuating. Personally I dont like it at all and if I were concerned about gas milage i would have not gotten a truck. Im pretty sure we all feel that way.

 

 

I think fuel economy is a side effect that happens to be a good buzz phrase. The real reason (IMO) is that battery warranty costs has been for many many years something that engineering has tried to get a handle on. Look at the battery on any GM vehicle for the last 15 years. Blankets to keep them cool, moving them to inside the passenger compartment or trunk for the same reason. I am almost positive (though I wouldn't know where to find it) that when the RVC system came out that there was an intro training overview that flatly stated battery warranty costs was what was being addressed by the system.

 

For what it is worth the way you feel about the battery not being deep cycle so this system degrades it is just not supported by the fact that battery warranty costs have dropped for the C/K platform dramaticaly since 2005.

 

 

In addition, the EPM function is designed to perform regulated voltage control (RVC) to improve battery SOC, battery life, and fuel economy. This is accomplished by using knowledge of the batteries SOC and temperature to set the charging voltage to an optimum battery voltage level for recharging without detriment to battery life.

[redvett]

The EPM function was started in 2005 on the #1500 series trucks.