GM Truck Club
THE PREMIER CHEVY TRUCK & SUV FORUM
Founded in 2004 ~ We're the #1 Chevy Truck & SUV Forum.
Silverado & Sierra | Tahoe & Yukon | Suburban & Yukon XL | SUV & CROSSOVER
Page 2 of 2 FirstFirst 12
Results 11 to 16 of 16
  1. #11

    Default

    My 05 has that dumb a$$ variable output charging system. It uses a hall effect sensor on the negative cable to tell the ecm what the alternator needs to produce, then the ecm tells the alternator what to do. I wonder if your sensor on the negative cable is bad? Another issue with them is that there are 2 different types of alternators for them. The bosch and the ac delco. THEY ARE NOT interchangeable. If you have the bosch you have to replace it with a bosch. trust me I went thru it. They autoparts folks know nothing about these systems. They can not bench teast one of these alternators, they must be tested on the truck. I had a crash course in this system when I had some charging issues. I put an delco alternator on it (I had a bosch) and it lasted a week or so. I ended up spending the $30 extra and buying a brand new bosch.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  2. #12
    Legend

    Join Date
    Sep 2010
    Location
    everett, massachusetts
    Posts
    1,321

    Default

    Quote Originally Posted by nates View Post
    Today was getting 14.2v both with and without the battery light on. I took off the battery cable, and the neg side had part of the boot pinched under it between the cable and the battery side terminal. I cut a little of it away so it would not interfere with the connection. No change. Disconnected my aftermarket stereo and amps (completely from the battery). No change. Checked for parasitic drain... at or under 250ma after 25 seconds, so I don't think any issue there.

    Still at a loss here.
    you should have stated that you have audio amps installed. also what is the power rating on these ? you using a capacitor ? what farad is it ?

  3. #13

    Default

    As I said I have the stereo totally unhooked at this point. I have a significant system that I listen to at low volume only. There is not much draw on my electrical system, and I've had no previous issues with this exact system in place for a long time. When I was young I used to care a lot more about this sort of thing. Now I find I'm listening to news radio about 99% of the time (that's getting old for you). Since installing the new Delco alternator I have not had any music through the system at all. To actually answer your question I've got 600 wats RMS from 3 amps feeding a single sub and 2 way components. No capacitor, because as I said I'm not bumping anything anymore, so no big power draws that would need it.

    Hall sensor definitely sounds like it could be the issue. Any testing criteria for it?
    Last edited by nates; 11-10-2013 at 10:57 AM.

  4. #14
    Legend

    Join Date
    Sep 2010
    Location
    everett, massachusetts
    Posts
    1,321

    Default

    Quote Originally Posted by nates View Post
    As I said I have the stereo totally unhooked at this point. I have a significant system that I listen to at low volume only. There is not much draw on my electrical system, and I've had no previous issues with this exact system in place for a long time. When I was young I used to care a lot more about this sort of thing. Now I find I'm listening to news radio about 99% of the time (that's getting old for you). Since installing the new Delco alternator I have not had any music through the system at all. To actually answer your question I've got 600 wats RMS from 3 amps feeding a single sub and 2 way components. No capacitor, because as I said I'm not bumping anything anymore, so no big power draws that would need it.

    Hall sensor definitely sounds like it could be the issue. Any testing criteria for it?
    the hall sensor measures current flow . if for some reason this indicates to the PCM low amps then the alternator will not be driven with the field excitation to produce normal output with this GM fuel saving device..one thing is for sure . many have this problem with this GM MPG saving add on.

    just make sure that you do have the correct alternator.

    - - - Updated - - -

    I found this info on a 2008 silverado with this system.

    Charging System Components

    Generator

    The generator is a serviceable component. If there is a diagnosed failure of the generator it must
    be replaced as an assembly. The engine drive belt drives the generator. When the rotor is spun it
    induces an alternating current (AC) into the stator windings. The AC voltage is then sent through
    a series of diodes for rectification. The rectified voltage has been converted into a direct current
    (DC) for use by the vehicles electrical system to maintain electrical loads and the battery charge.
    The voltage regulator integral to the generator controls the output of the generator. It is not
    serviceable. The voltage regulator controls the amount of current provided to the rotor. If the
    generator has field control circuit failure, the generator defaults to an output voltage of 13.8
    volts.

    Body Control Module (BCM)

    The body control module (BCM) is a GMLAN device. It communicates with the engine control
    module (ECM) and the instrument panel cluster (IPC) for electrical power management (EPM)
    operation. The BCM determines the output of the generator and sends the information to the
    ECM for control of the generator field control circuit. It monitors the generator field duty cycle


    2008 Chevrolet Silverado 1500
    2008 ENGINE Engine Electrical -Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
    2008 Chevrolet Silverado 1500
    2008 ENGINE Engine Electrical -Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
    signal circuit information sent from the ECM for control of the generator. It monitors a battery
    current sensor, the battery positive voltage circuit, and estimated battery temperature to
    determine battery state of charge (SOC). The BCM sends idle boost requests to the ECM.

    Battery Current Sensor

    The battery current sensor is a serviceable component that is connected to the negative battery
    cable at the battery. The battery current sensor is a 3-wire hall effect current sensor. The battery
    current sensor monitors the battery current. It directly inputs to the BCM. It creates a 5 volt pulse
    width modulation (PWM) signal of 128 Hz with a duty cycle of 0-100 percent. Normal duty
    cycle is between 5-95 percent. Between 0-5 percent and 95-100 percent are for diagnostic
    purposes.

    Engine Control Module (ECM)

    The ECM directly controls the generator field control circuit input to the generator. The ECM
    receives control decisions based on messages from the BCM. It monitors the generators generator
    field duty cycle signal circuit and sends the information to the BCM.

    Instrument Panel Cluster (IPC)

    The IPC provides a means of customer notification in case of a failure and a voltmeter. There are
    2 means of notification, a charge indicator and the driver information center (DIC) SERVICE
    BATTERY CHARGING SYSTEM message.

    the alternator should be outputting normal voltage with the headlights on. 13.75- 14.75 volts.. if not then this maybe the sensor/alternator/BCM/PCM.

    gm states that this hall sensor must not be moved from the OEM as built position...was this messed with ..

    then I found this
    Display Message: BATTERY NOT CHARGING SERVICE CHARGING SYSTEM or SERVICE
    BATTERY CHARGING SYSTEM


    The BCM and the ECM will send a serial data message to the driver information
    center for the BATTERY NOT CHARGING SERVICE CHARGING SYSTEM or SERVICE BATTERY
    CHARGING SYSTEM message to be displayed. It is commanded ON when a charging
    system DTC is a current DTC. The message is turned OFF when the conditions for
    clearing the DTC have been met. During cold weather warm-up and extreme
    electrical demand , the generator capacity can be briefly exceeded causing this
    message to be displayed for up to two minutes.
    Last edited by j cat; 11-10-2013 at 04:20 PM.

  5. #15

    Default

    I figured I would follow up on this thread now that I've got it worked out. I appreciate all of the help and input from you all. It turned out to be a bad battery. After having the battery tested 5 different times, at multiple places (actual load tests, both handheld and big machine versions) and having them always tell me it was good, replacing the alternator twice, and finally giving up on it all and finally taking it to GM for diagnosis, it turned out to be a bad battery... replaced under battery warranty. Done.

  6. #16
    Legend

    Join Date
    Sep 2010
    Location
    everett, massachusetts
    Posts
    1,321

    Default

    thanks for the repair info.

    I used to use sears batteries. over 10 years ago but stopped because of battery failures due to internal construction failures. I had two batteries fail the same way they internally opened at the negative battery connection.

    with what you reported I guess sears is not the place to go for battery checking if you have a die hard sears battery under warranty !

Page 2 of 2 FirstFirst 12

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •