Mitchell International
Friday, November 28, 2003 07:31PM
ARTICLE BEGINNING
1995 STARTING & CHARGING SYSTEMS
General Motors Corp. - Alternators & Regulators
Cadillac 4.6L: Concours, Eldorado, Seville
NOTE: This article covers the electronic Powertrain Control Module
(PCM) portion of the charging system. For bench testing
information and overhaul procedures, see the
ALTERNATOR & REGULATOR - TESTING & OVERHAUL article.
DESCRIPTION
The CS144, 140-amp generator is used along with the
Instrument Panel Cluster (IPC) and Powertrain Control Module (PCM). CS
stands for charging system; 144 denotes the outside diameter (in
millimeters) of the generator stator laminations.
The generator and related charging system circuitry has
self-diagnostic capability. A communication process has been
incorporated between the IPC, PCM and CS144 generator. When the
generator circuit voltage passes outside of programmed limits (10-16
volts), Codes I041, I042 and/or P016 will set. The malfunction may
also be indicated by BATTERY VOLTS LOW, BATTERY VOLTS HIGH or SERVICE
ENGINE SOON message on the Driver Information Center (DIC). Codes
I041, I042 and P016 will remain in PCM memory until cleared. See
MANUAL OPERATION OF SELF-DIAGNOSTICS under SELF-DIAGNOSTICS.
The IPC will also cause BATTERY NO CHARGE message to be
displayed on DIC if the generator regulator internally grounds the "L"
terminal. The PCM will set Code P110.
The voltage regulator is enclosed in a solid mold, mounted
inside the generator. A capacitor, mounted in the end frame, protects
the rectifier bridge from high voltage and suppresses radio noise.
OPERATION
The voltage regulator controls the field using a Pulse Width
Modulated (PWM) signal, measured in duty cycles. A PWM signal
continuously cycles on and off. On-time can vary within each cycle.
When the ignition switch is turned to the RUN position, the
PCM applies voltage to the regulator before engine is started. The
regulator, now in field strobe function, applies a small percentage of
the duty cycle to the field windings, which produce a magnetic field.
As generator RPM increases, the field strobe function is disabled and
normal regulation occurs.
When field current is on, the regulator switches the field
current on and off at a fixed frequency of about 400 cycles per ALTERNATOR & REGULATOR - SELF-DIAGNOSIS
second. By varying the overall time on and off, correct average field
current for proper system voltage control is achieved. At high speeds,
the on-time may be 10 percent. At low speeds with a heavy electrical
load, the on-time may be as much as 90 percent.
The PCM monitors the regulator from the "L" terminal of the
generator. The regulator will internally ground the "L" terminal when
it detects an internal fault. When this ground condition is sensed,
the IPC will cause BATTERY NO CHARGE message to be displayed on DIC.
The PCM will set Code P110.
SELF-DIAGNOSTICS
NOTE: Vehicle is equipped with elaborate self-diagnostics which
covers many on-vehicle systems. This article only covers the
portion of those systems which relates to charging system
diagnosis.
CAUTION: Accessing self-diagnostics for 30 minutes without running
engine will discharge battery, resulting in a possible
no-start condition. To ensure proper operation, attach
battery charger to battery.
ENTERING SELF-DIAGNOSTICS
NOTE: Diagnosis should not be attempted unless all IPC segments
illuminate, as it could lead to misdiagnosis. If any segment
is inoperative, affected display panel should be replaced.
1) Turn ignition on. Simultaneously push OFF and WARMER
buttons on Climate Control Center (CCC). Continue pushing OFF and
WARMER buttons until segment check appears (about 3 seconds) on
Instrument Panel Control (IPC).
NOTE: Failure of any segment to glow may result in inaccurate test
results. Replace any inoperative segment display before
proceeding with self-diagnostic process.
2) When segment check appears (all segments glow), system has
entered into self-diagnostic mode. Release both buttons. Driver
Information Center (DIC) will display diagnostic trouble codes.
Diagnostic trouble code level displays PCM codes first, followed by
IPC, ACP, SIR and TCS codes (if so prompted).
3) To proceed to desired level, press and release CCC HI (fan
up) button for "yes" or LO (fan down) button for "no". Press LO button
to go to next test level (i.e., IPC?, ACP?, SIR? or TCS?) or press OFF
button to return to next selection in previous test level.
4) At any time during display of diagnostic trouble codes,
system will exit self-diagnostic service mode and return to normal ALTERNATOR & REGULATOR - SELF-DIAGNOSIS
vehicle operation if AUTO or DEFOG button on CCC is pressed.
DISPLAYING TROUBLE CODES
1) After self-diagnostics is entered, any diagnostic trouble
code stored in memory will be displayed. Diagnostic trouble codes
appear in ascending (3-digit) numerical order and are prefixed by "P"
(PCM), "I" (IPC), "A" (ACP), "R" (SIR) or "T" (TCS). A final digit of
either a "C" (current) or "H" (history)" will also be indicated on
every code. Diagnostic trouble code level displays PCM codes first,
followed by IPC, ACP, SIR or TCS (if so prompted).
2) If no codes are present for a system, a "NO X CODE"
message (with X being system, i.e. "P", "I", etc.) will be displayed.
If communication line to a component is not operating, a "NO X DATA"
message will be displayed, indicating that IPC could not communicate
with that system.
3) At any time during display of diagnostic trouble codes, to
exit from service mode and go back to normal vehicle operation, press
AUTO or DEFOG button on CCC.
PCM CHARGING SYSTEM TROUBLE CODES
* Code P016
This code sets if generator voltage measured is less than 10
volts or greater than 16 volts for more than 5 seconds and
engine speed is equal to or greater than 500 RPM.
* Code P110
This code sets if PCM commands generator on and generator
feedback indicates that it is off for 15 seconds.
NOTE: After system completes diagnostic trouble code display
cycle, system can test charging system components and/or
circuitry indicated by trouble codes. See MANUAL OPERATION
OF SELF-DIAGNOSTICS under SELF-DIAGNOSTICS.
IPC CHARGING SYSTEM TROUBLE CODES
* Code I041
This code sets when engine is running at a speed greater than
800 RPM and IPC voltage is less than 10.6 volts for more than
2 seconds.
* Code I042
This code sets when engine is running at a speed greater
than 800 RPM and IPC voltage is greater than 16 volts for
more than 2 seconds.
Code I041 will cause BATTERY VOLTS LOW message to be
displayed. Code I042 will cause BATTERY VOLTS HIGH message to be
displayed. IPC will cause message BATTERY NO CHARGE to be displayed if ALTERNATOR & REGULATOR - SELF-DIAGNOSIS
generator regulator internally grounds terminal "L". The PCM will set
Code P0110.
MANUAL OPERATION OF SELF-DIAGNOSTICS
NOTE: Manual operation of self-diagnostic system is intended for
use with TROUBLE CODE CHARTS. Before using flow charts,
become completely familiar with procedures in MANUAL
OPERATION OF SELF-DIAGNOSTICS.
Making Selection Choices
During manual operating mode of self-diagnostics, buttons on
CCC function in following manners:
* LO
LO button is used to cycle through selection choices. In all
instances, continued use of this button will cause choices to
repeatedly cycle through all available choices.
* HI
HI button is used to confirm system/test selection choices.
Press this button when desired test or system is displayed.
* OFF
OFF button is used to back up (or escape) during selection
process. Continued pressing of this button will back up
manual operating mode to display of diagnostic trouble codes.
* AUTO or DEFOG
AUTO or DEFOG button may be pressed at any time during
display of diagnostic trouble codes or manual operating mode
to exit self-diagnostics service mode and return to normal
vehicle operation.
System Selection
1) After all trouble codes have been displayed (see
DISPLAYING TROUBLE CODES under SELF-DIAGNOSTICS), each available
system can be accessed for further specific diagnostic tests. First
system available for testing automatically displays. For example: PCM?
should now be present on display.
2) Pressing HI button on CCC will select displayed system for
testing. Pressing LO button on CCC will display next available system
selection.
3) This allows display to be cycled through all system
choices. List of systems will be repeated following end of system
list. Pressing OFF button on CCC will stop system selection process
and return display to beginning of diagnostic trouble code sequence.
NOTE: Test type selections are also available for Instrument Panel
Cluster (IPC) and are preceded with IPC (i.e. IPC DATA?, IPC
INPUTS?). ALTERNATOR & REGULATOR - SELF-DIAGNOSISArticle Text (p. 5)
1995 Cadillac Concours
Test Type Selection
After a specific system has been selected for testing, select
desired test type. Available test types include PCM DATA?, PCM INPUTS?
, PCM OUTPUTS?, PCM OVERRIDE?, PCM CLEAR CODES? and PCM SNAPSHOT?.
System may