Erratic Voltage Readings
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Joined: Sep 2011
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From: Alexandria Pa
Erratic Voltage Readings
2003 Auto. I get erratic voltage readings on the DIC. The relay and fuses are good, I checked and cleaned the grounds. I even had the alternator rebuilt it only needed the rectifier and a new pulley. Battery charges fine after driving I got 13 volts with the car off and battery disconnected. With the car running I get 14 to 14.2 volts at the battery. Could it possibly be the contacts in the ignition switch?
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checked the wires at the starter?
I am having a similar issue with my C6Z06, I get 14 when its cold but as the car gets hot the voltage is all over the map....I have been told the headers have an affect on the starters after a period of time and even without the headers the battery will charge differently when its hot out
I have a new alternator and new battery, guy at the shop told me he had the same issues and it went away when he installed a new starter...I'm just gonna deal with it until it goes completely
I am having a similar issue with my C6Z06, I get 14 when its cold but as the car gets hot the voltage is all over the map....I have been told the headers have an affect on the starters after a period of time and even without the headers the battery will charge differently when its hot out
I have a new alternator and new battery, guy at the shop told me he had the same issues and it went away when he installed a new starter...I'm just gonna deal with it until it goes completely
Thread Starter
Advanced
Joined: Sep 2011
Posts: 54
Likes: 2
From: Alexandria Pa
checked the wires at the starter?
I am having a similar issue with my C6Z06, I get 14 when its cold but as the car gets hot the voltage is all over the map....I have been told the headers have an affect on the starters after a period of time and even without the headers the battery will charge differently when its hot out
I have a new alternator and new battery, guy at the shop told me he had the same issues and it went away when he installed a new starter...I'm just gonna deal with it until it goes completely
I am having a similar issue with my C6Z06, I get 14 when its cold but as the car gets hot the voltage is all over the map....I have been told the headers have an affect on the starters after a period of time and even without the headers the battery will charge differently when its hot out
I have a new alternator and new battery, guy at the shop told me he had the same issues and it went away when he installed a new starter...I'm just gonna deal with it until it goes completely
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I believe in the Beer Fairy
The dash gauges are AFTER the ignition switch, a well known weak point on the C5, so it is not uncommon for the gauges to report a lesser voltage than is actually at the battery posts. 
Still very worth while to check the wires to/from the alternator at the starter solenoid as well as the condition of the connection of the positive battery cable at that same location. Heat cycles from headers can cause the connection to become loose as well as oxidized that can cause fluctuations while the vehicle is on the road.
Still very worth while to check the wires to/from the alternator at the starter solenoid as well as the condition of the connection of the positive battery cable at that same location. Heat cycles from headers can cause the connection to become loose as well as oxidized that can cause fluctuations while the vehicle is on the road.
I guess what I'm trying to say is the DIC reading doesn't match my handheld voltmeter when the car is running. The DIC is the only part that is erratic when it is running. The handheld is steady and smooth 14 to 14.2 volts with very little load, and 13.5 to 13.7 volts with heavy load. The DIC would read 14.0,13.8,13.9,13.5 and steady decreasing readings. The battery never has shown any readings below 12.8 volts not running and disconnected at the negative post. I will check my starter wires and connection just to be sure.
