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Hi,
I have read a lot of posts about the stock alternator on the 2007 C6 base which is what I have.
I have changed the alternator to a 145 amp version and also put in a new battery.
The problem is at night with headlights on (nothing else on), the voltage reads fine for about 10 mins at idle, then slowly drops down below 13 on the dash gauge.
When I put a meter on the alternator, it holds steady at 14 volts all the time.
When I put the same meter on the battery terminals, it also reads about 13.6 volts steady.
When I am driving at highway speeds, the gauge seems to creep back up to 14 volts and stay there until I return to idle.
Where is the dash gauge getting it's information, because it seems it's wrong. I have confirmed this using three different multimeters.
I have thought about putting a pillar pod up with an aftermarket gauge since it seems the stock one is faulty.
Any opinions on this?
Hi,
I have read a lot of posts about the stock alternator on the 2007 C6 base which is what I have.
I have changed the alternator to a 145 amp version and also put in a new battery.
The problem is at night with headlights on (nothing else on), the voltage reads fine for about 10 mins at idle, then slowly drops down below 13 on the dash gauge.
When I put a meter on the alternator, it holds steady at 14 volts all the time.
When I put the same meter on the battery terminals, it also reads about 13.6 volts steady.
When I am driving at highway speeds, the gauge seems to creep back up to 14 volts and stay there until I return to idle.
Where is the dash gauge getting it's information, because it seems it's wrong. I have confirmed this using three different multimeters.
I have thought about putting a pillar pod up with an aftermarket gauge since it seems the stock one is faulty.
Any opinions on this?
It sounds like everything is working normally. If you are wanting more accurate readings, use the DIC digital readout instead of the analog gauge.
It sounds like everything is working normally. If you are wanting more accurate readings, use the DIC digital readout instead of the analog gauge.
The problem with the DIC is that it reads the same voltage as the gauge does.
This is why i wonder where in the system it it getting it's voltage from, because it can't be from the battery.
It has to be downline from the battery somewhere, since the voltage from the alternator to the battery and the battery itself
reads much higher than what the DIC and the gauge read.
Thanks for the reponse.
The problem with the DIC is that it reads the same voltage as the gauge does.
This is why i wonder where in the system it it getting it's voltage from, because it can't be from the battery.
It has to be downline from the battery somewhere, since the voltage from the alternator to the battery and the battery itself
reads much higher than what the DIC and the gauge read.
Thanks for the reponse.
It is...that voltage is coming from the ECM, it will not match the direct battery voltage. The analog gauge is simply a representation of the DIC voltage...it will be the same by default. All the analog gauges get info from the ECM directly and then display the analog representation of it.
Voltage at the alternator (back terminal under the rubber cover) to the body of the alternator when the car is idling and the A/C off should be 14.7v.
At the battery terminal with the car idling, should be at 14.5v. If your getting lower than this, but 14.7 at the alternator, then go from the positive cable on the battery and use the body of the alternator body as your ground point for the tester. If this corrects the problem with the voltage at 14.5, the you have a bad connection from the negative cable to the engine block above the starter. If going to body of the alternator does not solve the problem, then bad positive connection point between the alternator and battery cable at at the starter instead.
Note, do the same test off the fuse block positive point back to the battery negative terminal/ body of the alternator and still should be 14.5 volts with the alternator at 14.7 volts.
Now as pointed out, the DIC is all digital, including the dial voltage gauge as well, and its getting is digital signal from the ECM to read out voltage at the ECM.
So from the engine fuse block terminal, power goes first to the BCM, then to the ECM. So with voltage of 14.7 at the alternator, 14.5 at the battery, the ECM/DIC voltage should be at 14.3.
If your voltage at the DIC is less than 14.3V with the alternator at 14.7 (and again the A/C off) and battery at 14.5, then the problem will be either in the engine fuse block, to the BCM connector and its fuse block, or the ECM connector at the end of line isntead.
Now the salt in the wound if you do have all the correct voltages, the stock Valeo alternator at idle only puts out about 14amps, and is enough for the basic engine before the radiator fan kick on. When the motor gets hot to cause the radiator fan to turn on, or you turn the A/C on which will cause the radiator fan to come on to draw air through the heat exchanger in front of the radiator, the radiator fan itself pulls down about 20 amp (more that the alternator is putting out, and cause a draw on the battery to keep up with the demand). So in these cause with a hot day and the A/C on, it not uncommon for the DIC to drop down to around 13.9~13.8 volts isntead.
Service Charging System Still On after Alternator Replacement
I have a 2007 c6 corvette (Canadian variant) ls2 6-spd with 21,800+ kms or 13,000+ miles. I recently had my alternator replaced because it was whining and the service charging system came on with an OEM ACDELCO Alternator 25888970 from Summit Racing. Fixed the problem and I can drive the car again.
After replacing the alternator, I suddenly encountered a new problem, the service charging system came back on. I cleaned up the ground terminals below the battery tray, and cleaned up the ground and positive terminals connected to the battery. No more service charging system, but volt meter reading was still a bit erratic but not as bad as when I didn’t clean them yet. When it’s cold, the volt meter reading on the dash is at 14.2. But at operating temp it would run between 13.4 -13.8 volts in city driving (stop and go). I brought it to the shop, they checked the alternator and the battery, they said that a volt meter reading from the alternator came out between 14.3-14.5 volts while the battery volt meter reading was similar. Although when it came to the volt meter reading on the dash it was reading around 13.4 -13.8 at operating temp. They also checked the ground wires and the ground wire connected to the starter and said it was tight and not loose.
I have been using it during weekends now, and I decided to start it up tonight (10/03/2023), and when it started the volt meter on the dash was reading 14.1 volts but the service charging system lit up again. I drove it around and it was driving fine so I really don’t know what’s causing this. Any technical advice would be much appreciated. Attached pictures below. One is during cold start and the other during operating temp. Cold start Operating temp (CEL due to straight pipe)
Would bank that the alterantor is not the correct unit, and has a voltage regulator in it, for the C5 instead. Or, horn or alternator sensing fuse is blown and why car is not seeing the voltage on the voltage regulator pins.
I read the thread you sent me, I’ll check if it’s sending that code to the scanner. Could they still install a C5 voltage regulator even if I ordered a brand new OEM ACDELCO Alternator? I’ll check the fuses as well if it’s I didn’t order a rebuilt one. But I’ll double check to make sure. My corvette has no cats, no reso, and no muffler hence the CEL. The reason why it didn’t have it in the pic above was because I changed the battery! Lol. Thank you for the reply! I’ll double check everything.
Battery meter reading on dash
