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Electrical problems. We got new alternator; problem still exists. Instrument panel indicates that sometimes battery isn't being charged; that oil & ATF need immediate change; I noticed headlights & most electrical accessories will stop working & will come back on randomly for long periods of time; battery is frequently being drained; brake light always work though; maybe a short somewhere. We've put a lot of money into it, but problem not solved. Please help!
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Question edited for clarity.
Question moved to model category.
Jeff's great answer ^^^Up There^^^ is better down here as a Solve.
Jeff Armer Aug 20, 2022
With it running test voltage at the battery. Sounds like it's not charging the battery. Had alternator check? is good, but that doesn't mean it's working in the car. The charging system in your vehicle is computer controlled, is the battery light lit in the instrument cluster ? Could have DTC'S - diagnostic trouble codes stored . Do you know if your car has regulated voltage control or is a none regulated voltage control system.
Charging System Description and Operation (w/RVC)
Electrical Power Management (EPM) Overview
The electrical power management (EPM) system is designed to monitor and control the charging system and send diagnostic messages to alert the driver of possible problems with the battery and generator. This EPM system primarily utilizes existing on-board computer capability to maximize the effectiveness of the generator, to manage the load, improve battery state-of-charge (SOC) and life, and minimize the system's impact on fuel economy. The EPM system performs 3 functions:
• It monitors the battery voltage and estimates the battery condition.
• It takes corrective actions by adjusting the regulated voltage.
• It performs diagnostics and driver notification.
The battery's condition is estimated during key-off and during key-on. During key-off the SOC of the battery is determined by measuring the open-circuit voltage. The SOC is a function of the acid concentration and the internal resistance of the battery, and is estimated by reading the battery open circuit voltage when the battery has been at rest for several hours.
The SOC can be used as a diagnostic tool to tell the customer or the dealer the condition of the battery. Throughout key-on, the algorithm continuously estimates SOC based on adjusted net amp hours, battery capacity, initial SOC, and temperature.
While running, the battery's degree of discharge is primarily determined by a battery current sensor, which is integrated to obtain net amp hours.
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 battery's SOC and temperature to set the charging voltage to an optimum battery voltage level for recharging without detriment to battery life.
The Charging System Description and Operation is divided into 3 sections. The first section describes the charging system components and their integration into the electrical power management (EPM). The second section describes charging system operation. The third section describes the instrument panel cluster (IPC) operation of the charge indicator, driver information center (DIC) messages, and voltmeter operation.
Charging System Description and Operation (w/o RVC)
Circuit Description
The generator provides voltage to operate the vehicle's electrical system and to charge its battery. A magnetic field is created when current flows through the rotor. This field rotates as the rotor is driven by the engine, creating an AC voltage in the stator windings. The AC voltage is converted to DC by the rectifier bridge and is supplied to the electrical system at the battery terminal.
When the engine is running, the generator turn (on) signal is sent to the generator from the powertrain control module (PCM), turning ON the regulator. The generator's voltage regulator controls current to the rotor, thereby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. When the engine is started, the regulator senses generator rotation by detecting AC voltage at the stator through an internal wire. Once the engine is running, the regulator varies the field current by controlling the pulse width. This regulates the generator output voltage for proper battery charging and electrical system operation. The generator F-terminal is connected internally to the voltage regulator and externally to the PCM. When the voltage regulator detects a charging system problem, it grounds this circuit to signal the PCM that a problem exists. The PCM monitors the generator field duty cycle signal circuit.
Charging System Indicator
The instrument panel cluster (IPC) illuminates the charge indicator in the message center when the following occurs:
• The powertrain control module (PCM) detects that the generator output is less than 11 volts or greater than 16 volts. The IPC receives a serial data message from the PCM requesting illumination.
• The IPC determines that the system voltage is less than 11 volts or greater than 16 volts. The IPC receives a serial data message from the body control module (BCM) indicating the system voltage.
• The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.
• The ignition is ON, with the engine OFF.
Did you test for battery voltage on larger wire on the back of the alternator - could have a bad wire -corrosion inside you can't see . Could also have blown fusible link on that wire - comes from the starter B+ post.
When the vehicle is running check voltage at the battery . should be 13.1 to 14.1 volts , if not the alternator isn't charging . Doesn't matter if the alternator is new , has to have B+ voltage on the heavier wire connected to back of the alternator . The other wire connected to the alternator comes from the PCM/ECM . Is the Battery symbol light on when vehicle is running ?
The powertrain control module (PCM) or vehicle control module (VCM) turns the generator ON or OFF, by applying voltage to the generator control/monitoring circuit 225 (RED). The regulator in the generator also requests the charge indicator located in the instrument panel cluster (IPC), using the same circuit. When the regulator monitors that either a voltage high or voltage low condition exists with the engine running, a ground path to the PCM/VCM will be provided through the generator control/monitoring circuit 225. The PCM/VCM then sends a serial data message to the IPC requesting the charge indicator to be turned ON. The IPC monitors serial data messages from the PCM/VCM, and turns the charge indicator ON when requested. It mite be best if you take your vehicle to a qualified repair shop , unless you like making parts stores rich , buying unneeded parts .
sounds like you need to have the alternator checked, if it were the instrument cluster the van would still run, you may still have a problem with the cluster, but the running 2 miles and the battery going dead is the charging system, you may have two problems. fix the charging system first then worry about the dash.
Your battery is suspected to be low in power But check if thegrounding of the battery is tight and the positive terminalis also tight.If not put your battery on charge.
I understand that you are takinga whole lot of trouble to do this routine of charging and connecting.I must advise you to disconnect the drain voltage circuit like the remotecontrol or the car system.connect them to a main switch and put it off in the night.If you cannot rectify the fault of these units.Now after the battery is charged crank and start the engine and measure the charging voltage.Check voltage of alternator to the rectifier regulator module.If charging is low this unit can be defective.If so replace.
It indicates low or too much voltage. It's either a low battery, a voltage regulator that is going out (it's built into the alternator), or an alternator that is not charging the battery back up. If you know for a fact that the battery is good (not old and it holds a charge ok), pull the alternator and take it to a local auto parts store. Most of them will test it for free.
Volt light - on instrument panel usually would indicate you to get a battery. If you can get your car started, take your vehicle to any auto parts store that offer free electrical/ charge check just to make sure. It also could indicate a regulator in your alternator not holding charge either. If your battery is not a maintenance-free type, carefully remove the caps on top of the battery and check the water levels. Be sure to only use 'Distrilled Water' if needing to add to your battery.
chk charging noltage at battery posts. should be in 13.6 to14.2.. Is charging good at 13.8. If thar's good, your battery is not.. Your alternator won't last too long with a bad battery. good luck
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