Voltage issues, alternator?
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Joined: Dec 2019
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C5 Diag,
Yep, I just re-read post #1.. I got Side Tracked...
I have an ongoing prob with my tire pressure sensors after anew set of tires. So I was stuck on reduced speed, daa. Thanks for the head-up
One of this dealer employees broke one sensor and days latter two more failed. I been dealing with Reduced Speed and 7 trips back.. Their call Thursday said they had yet another new sensor. I expect it's China parts and not Delco as they say... Oh, and two new front tires because the balance weight was too large,, Continental. My HHR Panel (FWD) would immediately complete a Major Power Reduction with a front wheel that started to Spin, was a PITA.
APP and MAF sensor.. Well We all try to believe that all Visually Displayed and audio alerts mean that the a error with be logged in the appropriate module, somewhere. Nope, I've seen enough myself to dispute that thought / statement. At least the owners car has the later ECM and not the early ECM.
I'm not clear for me if he has checked all the modules on his Instrument panel, so hopefully he does so there's at least that data could help..
However, "14.89 at back of alternator and 14.7 at the battery"" is generally too high for an AGM even a liquid wet cell, Battery. There's no technical info that I've personally read as to the max VDC without electronics damage in any GM ECM or other modules. From personal experience, in many MPU (micro-processor ) designs, over voltage is Fatal, and this circuity involved creates a significant mount of heat esp in power hungry modules like a ECM driving 8 coils and 8 injectors.
But, I'm still wondering about poor grounds in this C5. And if so, a module(s) or Sensor, all electronic contain electronic components) could have been damaged, but not Dead Yet. . Electronic Semiconductors don't do well with poor grounds. I typically go overboard of circuit trouble shooting and start review a similar design in my head.
At any rate, he got some tests and reading ahead. Hope he solves this problem soon.
Thanks,,
Michael..
Yep, I just re-read post #1.. I got Side Tracked...
I have an ongoing prob with my tire pressure sensors after anew set of tires. So I was stuck on reduced speed, daa. Thanks for the head-up
One of this dealer employees broke one sensor and days latter two more failed. I been dealing with Reduced Speed and 7 trips back.. Their call Thursday said they had yet another new sensor. I expect it's China parts and not Delco as they say... Oh, and two new front tires because the balance weight was too large,, Continental. My HHR Panel (FWD) would immediately complete a Major Power Reduction with a front wheel that started to Spin, was a PITA.
APP and MAF sensor.. Well We all try to believe that all Visually Displayed and audio alerts mean that the a error with be logged in the appropriate module, somewhere. Nope, I've seen enough myself to dispute that thought / statement. At least the owners car has the later ECM and not the early ECM.
I'm not clear for me if he has checked all the modules on his Instrument panel, so hopefully he does so there's at least that data could help..
However, "14.89 at back of alternator and 14.7 at the battery"" is generally too high for an AGM even a liquid wet cell, Battery. There's no technical info that I've personally read as to the max VDC without electronics damage in any GM ECM or other modules. From personal experience, in many MPU (micro-processor ) designs, over voltage is Fatal, and this circuity involved creates a significant mount of heat esp in power hungry modules like a ECM driving 8 coils and 8 injectors.
But, I'm still wondering about poor grounds in this C5. And if so, a module(s) or Sensor, all electronic contain electronic components) could have been damaged, but not Dead Yet. . Electronic Semiconductors don't do well with poor grounds. I typically go overboard of circuit trouble shooting and start review a similar design in my head.
At any rate, he got some tests and reading ahead. Hope he solves this problem soon.
Thanks,,
Michael..
Thanks for all the help. I've removed and inspected 4 under hood grounds, no corrosion and all actually look new but I hit them with a wire brush and reinstalled for the heck of it. 14.89v at back of alternator initially, once I've been driving for a while (no accessories on) voltage drops to 14.2 at back of alternator and 13.88 at battery (both measured while running) should voltage stay consistent at all times unless an accessories is powered on? Is this gradual voltage drop normal?
The problem never happens immediately but after I drive. Its about the time the car is at full operating temperature but also about the time the voltage has come down. Both of those could be coincidence maybe. It drives like a plug wire is off when this happens.
could it be a bad coil that acts up when hot?
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Joined: Apr 2007
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From: South Western Ontario
Racer
Joined: Jan 2015
Posts: 499
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From: Arkansas
408FRC,
What maker of Volt /meter are You using and have you tested it's VDC accurately ??
Your full change Voltage should be 12.2 -- 14.4 max for a AGM
Maintenance charge when the battery is full should be 12.8 -13.2 max.
Your Meter may be reading high 0.5 to 0.6 VDC high, I hope.
Your Alt uses a sense wire connector to control the Voltage, measure your Voltage at the Battery
Michael..
What maker of Volt /meter are You using and have you tested it's VDC accurately ??
Your full change Voltage should be 12.2 -- 14.4 max for a AGM
Maintenance charge when the battery is full should be 12.8 -13.2 max.
Your Meter may be reading high 0.5 to 0.6 VDC high, I hope.
Your Alt uses a sense wire connector to control the Voltage, measure your Voltage at the Battery
Michael..
