Justin24

Hi everyone, I'm looking for some advice on the "service electrical system" code that my car threw a few days ago. My car is heads/cam. I did a small pull in 1st gear with traction control on and had some wheelhop and tirespin. Almost immediately, this code flashed. The car seems to be running fine other than throwing this code, although the lope of the exhaust seems just a bit off (or it might be my ears). The headlights, taillights, blinkers, horn, interior lights, etc. all work just fine. The car has no trouble starting. When I checked the battery, it was loose and able to move around a bit. I tightened it up to no avail. When running the car, the voltage is always 14-15. I know I'll probably have to take it to the dealer, but I have a fear that I'll be spending a lot of money and chasing this problem for a long time before it is actually fixed. I would greatly appreciate any input!

MTPZ06

Clear the code and see if it returns before doing that IMO.

What was the actual code #?

Justin24

I've tried hitting the reset button on the dash, but the message pops back up within a few minutes. I'm not sure how to find the actual code without a scanner. Is it possible?

Thank you for your input.

MTPZ06

No, but you can go to your local auto parts store...NAPA, etc. and they typically have a scanner and can read codes for you.

BGCZO6

I was told after headers were installed and a tune a service electrical message would show instead of a check engine light.

Justin24

I hope this is not the case, but I really appreciate the info. Can anyone else confirm this?

Dan_the_C5_Man

The check engine light is primarily triggered for emission-related issues, and the service electrical system message isn't going to be displayed for emissions-related problems just because you have a tune. In most cases, the emission-related issues no longer trigger the MIL / check engine light, depending on what the tuner shut off or suppressed.

Bill Dearborn

An OBD II scanner may not be able to read the code generating the message. They are pretty limited to engine/emissions problems and don't recognize other codes coming from the car. However, there are some P Codes that are related to the charging system and may generate the message you are seeing.

Here is what the FSM has to say about diagnosing the message (see bottom):
Charging System Description and Operation
Generator
The generator features the following major components:

• The delta stator

• The rectifier bridge

• The rotor with slip rings and brushes

• A conventional pulley

• The regulator

The slip ring and the frame are liquid cooled.

The generator features permanently lubricated bearings. Service should only include tightening of mount components. Otherwise, replace the generator as a complete unit.

Regulator
The voltage regulator controls the rotor field current in order to limit the system voltage. When the field current is on, the regulator switches the current on and off at a rate of 400 cycles per second in order to perform the following functions:

• Radio noise control

• Obtain the correct average current needed for proper system voltage control

At high speeds, the on-time may be 10 percent with the off-time at 90 percent. At low speeds, the on-time may be 90 percent and the off-time 10 percent.

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 engine control module (ECM), 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 ECM. When the voltage regulator detects a charging system problem, it grounds this circuit to signal the ECM that a problem exists. The ECM monitors the generator field duty cycle signal circuit. The system voltage sense circuit receives B+ voltage that is Hot At All Times through the HORN/ALT SENSE fuse in the underhood junction block. This voltage is used by the regulator as the reference for system voltage control. On vehicles that use a sense circuit connected to the voltage regulator, this circuit must be operating properly for the charging system to work correctly, when there is a charging system concern all circuits at the generator should be tested.

Charging System Messages
The driver information center (DIC) displays a charging system message the when the following occurs:

• The engine control module (ECM) detects that the generator output is less than 11 volts or greater than 16 volts. The DIC receives a serial data message from the ECM requesting illumination of a charging system message.

• The instrument panel cluster (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.

BATTERY SAVER ACTIVE
The DIC displays the BATTERY SAVER ACTIVE message when the BCM reduces or disables the performance of some vehicle systems in order to reduce the load on the charging system. The DIC receives a serial data message from the BCM requesting illumination.

BATTERY VOLTAGE HIGH
The DIC displays the BATTERY VOLTAGE HIGH message when the IPC determines that the system voltage is greater than 16 volts. The IPC receives a serial data message from the BCM indicating the system voltage.

BATTERY VOLTAGE LOW
The DIC displays the BATTERY VOLTAGE LOW message when the IPC determines that the system voltage is less than 11 volts. The IPC receives a serial data message from the BCM indicating the system voltage.

SERVICE CHARGING SYSTEM
The DIC displays the SERVICE CHARGING SYSTEM message when the ECM detects a malfunction with the generator output. The IPC receives a serial data message from the ECM requesting illumination.

SERVICE ELECT SYSTEM
The DIC displays the SERVICE ELECT SYSTEM message when the ECM detects a malfunction with the generator output. The IPC receives a serial data message from the ECM requesting illumination.

One thing I would check before running to the dealer is the battery condition and the condition of the battery cables to make sure you have the proper voltage and have no corrosion on the battery cable connectors or loose connectors. Also check the starter solenoid where the battery positive cable is attached to make sure it is in good condition.

Bill

Justin24

Sorry to resurrect this thread, but the problem is solved. It was the o2 sensor(s). After they were replaced, the code went away and has not come back on after a 100+ miles. The car is so much more responsive now. It pulls harder and the torque down low is vastly improved. I now have a feeling that the o2 sensors were failing for quite a while, because the car never felt this good. The car never felt like a true H/C/I car, but it sure does now. Thanks everyone for your input on this!

MTPZ06

Thanks for coming back to post the resolution.