Question about 1995 Jeep Grand Cherokee

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How to troublesoot alternator not carging. between PCM or alternator. Getting 30 volts at B+ wire, Batt. voltage at one field wire and 2 0r 3 at other. Thanks.

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You have a bad diode I could give you a lenghtly bench test procedure to test them but you can;t service them and you have told me enough to know what the problem is A diode lets current flow in one deriction and stops it from flowing back in the other You have 30 volts on one side and 2 volts on the other cut that in half and you have about 16 volts witch would be vary good if you had it on bolth sides so i think you need a new one hoped this helped

Posted on Nov 14, 2010

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The alternator is only supposed to put out 14.7 to 15 volts max from the back of the alternator to ground if it is 30 the regulator in alternator is shorted needing the alternator replaced.

Posted on Nov 14, 2010

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My battery light came on while i was driving than a few minutes later everything shut off. The battery was replaced in january and alternator was replaced in october.. what could be the problem?


For the alternator to work B+ voltage must be applied to the heavier gage wire on the back of the alternator ,plus the alternator is computer controlled , by the PCM !
Charging System Indicators
BATTERY The IPC illuminates the battery indicator when the following occurs:
?€¢
The PCM detects that the generator output is less than 11 volts or greater than 16 volts. The IPC receives a class 2 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 class 2 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.
BATTERY NOT CHARGING The IPC illuminates the battery not charging indicator in the driver information center when the following occurs:
?€¢
The PCM detects that the generator output is less than 11 volts or greater than 16 volts. The IPC receives a class 2 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 class 2 message from the body control module (BCM) indicating the system voltage.


Your best is to have a qualified repair shop check it out ! Could have DTC'S - diagnostic trouble codes stored !
DTC P0562
The powertrain control module (PCM) continuously monitors that the system voltage stays within the proper range. If the PCM detects an excessively high system voltage, DTC P0563 will set. A high voltage condition may cause a stalling condition or other drive ability concerns.
DTC P0621
The powertrain control module (PCM) uses the generator turn on signal circuit to control the generator. A high side driver within the PCM allows the PCM to turn the generator ON and OFF. When Generator operation is desired, the PCM sends a 5 volt signal to the voltage regulator via the generator turn on signal circuit. This causes the voltage regulator to begin controlling the generator field circuit. Once the Generator is enabled by the PCM, the voltage regulator controls generator output independently of the PCM. Under certain operating conditions, the PCM can turn Off the generator by turning Off the 5 volt signal on the generator turn on signal circuit. The PCM has fault detection circuitry which monitors the state of the generator turn on signal circuit. If the fault detection circuit senses a voltage other than what is expected, this DTC will set. The voltage regulator also contains fault detection circuitry. If the regulator detects a problem, the regulator will ground the generator turn on signal circuit, pulling the voltage low. This also causes the PCM to set the DTC.
DTC P0622
Checking for codes an voltage drop testing the connections an using a scan tool to check data parameters is the only way to solve your problem . Which means taking to a qualified repair shop !

Jul 26, 2016 | 2002 GMC Envoy

1 Answer

I HAVE A 2003 PT CRUISER AND THE BATTRY LIGHT IS ON NEW BATTERY NEW ALT AND THEY SAY IT IS THE VOLTAGE REG


The PT cruiser uses a field signal from the PCM to regulate the voltage. If you are not getting approximately 14 volts at the battery terminals when the engine is running, either:
  1. The replacement alternator is faulty.
  2. The generator field control signal from the PCM is faulty.
  3. The Fusible Link between the alternator and the Starter Motor (which is also the same electrical point as the battery positive terminal is open.
Use the diagram below and check the alternator output at the point labeled "A11 6 BK/GY" If this is 14 volts and there is not 14 volts at the battery terminals, then the Fusible link is bad. If there is no voltage or way less than 15 volts at the alternator, then the alternator or the PCM field signal is bad. Ensure the connector from the PCM is connected properly.


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Sep 27, 2015 | 2003 Chrysler PT Cruiser

1 Answer

It showing code 41. Generator field not switching properley.


This trouble code sets when the Powertrain Control Module (PCM) tries to regulate the generator field with no result during monitoring.
The PCM tries to maintain a system voltage between 12.9 volts and 15.0 volts. The voltage determined by the PCM as the final goal for the charging system is called "control" voltage. This control voltage is determined from the battery temperature sensor for ambient sensor and the sensed voltage system voltage at PCM pin #11.
The control voltage is compared to the sensed voltage continuously during running. If the sensed voltage is less than the control voltage, the PCM will supply more ground to the field circuit. If the sensed voltage is more than the control voltage, the PCM will supply less ground to the field circuit.
There are three possible causes for this, the field driver circuit open or shorted, there is an alternator internal open or short os a PCM failure

Jun 04, 2015 | Cars & Trucks

1 Answer

1989 dodge 250 the red ignition wire is getting hot and melting in two when the key is turned to the run position


Blue wire to ignition switch,from alternator voltage regulator.( 12 volts ) ECU power wire, Red wire to battery terminal. Blue wire goes from alternator to the ignition switch. The voltage regulator senses the incoming voltage from the blue wire. ) it grounds the green field wire This energizes the alternator field, and the alternator begins to produce a charge and sends it to the battery via the main output wire. When the voltage regulator senses 14 volts from the blue field wire, it cuts the ground to the green field wire. Good-Day!

Sep 21, 2014 | Cars & Trucks

1 Answer

Loss of power


stock car YJ ? , or all hacked up. (old cars get hacked)
2.5 or 4.0 liter engine? still have a real jeep alternator not upgraded?

loss of electrical power (first rule, we never need to guess.!!!)
not with a voltmeter. (tool that costs $20 )
alternator good (by what means, autozoned?) ( we can find out one car)
but low on gauge. what gauge in dash voltmeter.? sure...
i think you car has no charge lamp only the dash VM.

own an volt meter? a DMM? hand volt meter?

1: if the alternator charge lamp is stuck on driving.
2: is battery voltage at 13.3 to 15vdc with engine at 800 RPM idling
alternator belt not slipping, for sure.....???
if the battery voltage is near 12.5v and falling running that is
an Alternator system failure, note i said, system. !!!

this is first. if we get to here. we can find the real cause.
test 3:
is the charge lamp on keyon, and goes out running?
make sure the big fuse for the alternator in the engine bay fuse
box is not blown, 50amp?

I have no 95 FSM and my online source sucks for 95

Alternator dead: (alt good)
1: belt slipping . engine at 300rpm, nah.
2: fuse blown, the big one. (engine bay fuse box)
3: ;wrong alternator, there are many, most others will fail, even good ones.......
4: alternator ground bad. (end to end, to battery minus)
5: bad wiring to same. bad connections, any to battery or alt.
6: some jeeps the PCM has the field regulator, see link below.
ECU pin 20 , is field pin, it is on 95, 4.0L (engine not stated)

is the CEL lamp on, and throwing code 41 DTC?, alt, field errors?

the alt has 4 pins, battery, field,ground and voltage sense.
The reg is in the PCM. and if bad is a bad $3 transistor..
see same form for fix for that issue..

i think this is same as your. 1996 is big change year.
http://www.jeepforum.com/forum/f12/1993-wrangler-pcm-ecu-ecm-pin-out-diagram-1170004/


you can test the alt, PCM wire pulled !, by full fielding the alt.
grounding the field term, no wires on field pin of alt.
see FSM for details on that.
The PCM modulates the field pin to control charge at all times.

Dec 17, 2013 | 1995 Jeep Wrangler

1 Answer

Take post off positive on 89 caprice classic 305 and the car dies that's 2 alternators I try


it's normal to engine to stall because alternator won't keep engine running. the field control of alternator goes with the batt.voltage then no batt.voltage no field control then no charge
look for good connection at alternator . look for current on one of 2 wire alternator ignition key on (is control by a fuse)

Oct 15, 2013 | 1985 Chevrolet Caprice

1 Answer

I am getting P0622 on my Chrysler Town and Country. I have a brand new battery and the alternator tested good at Auto Zone. I got 12.4 volts at the battery with the van off and between 7 and 8 volts...


if you getting 12.4 volts with no power load and engine goes down to 7-8 volt should be between 13-14 volts on idle would say the voltage regulator has gone.some are replaceable but most are not so you will need a new alternator or a secondhand one that is know to be working.

Sep 15, 2013 | 2001 Chrysler Town & Country

1 Answer

2005 lincon aviator charing system 12.2 volts after alternator install


check the black/orange wire at the alternator for battery voltage if no power check the fuesable link ( A )

check the orange/light blue wire at the alternator for battery voltage if no power check the fuesable links ( B & C )

check the light green/red wire for 12 volt with the engine running if no power replace the PCM.

if all wires have the proper voltage then replace the alternator

GOOD LUCK

Dec 31, 2011 | Oldsmobile Aurora Cars & Trucks

3 Answers

2003 windstar alternator over charge I try 5 or 6 alternator diferent companie always the same problem go up to 18.80 v help me please


it should notgo over 14 1/2 volts.

Get free DTC codes scan from Autozone. I think you will get DTC code 1246 - System Voltage Malfuction.

The I (indicator) (BAT light) wire activates alternator field circuit.

The heavy B wire circuit sends current to the battery for charing and to run the car.

The S circuit helps control the amount of charge. I suspect yours is not controlling. This car has the PCM (engine computer) help control the output and turn the BAT light on when under or over charging.

SECTION 414-00: Charging System - General Information 2003 Windstar Workshop Manual
DESCRIPTION AND OPERATION Charging System This vehicle is equipped with a powertrain control module (PCM)-controlled "smart charge" charging system. The PCM-controlled charging system is a system whereby the PCM determines the optimal voltage setpoint for the charging system and communicates this information to the voltage regulator. The PCM-controlled charging system is unique in that it has two uni-directional communication lines between the PCM and the generator/regulator. Both of these communication lines are pulse-width modulated. The GEN COM line communicates the desired setpoint from the PCM to the voltage regulator and the GEN MON line communicates the alternator load condition to the PCM. The third pin on the voltage regulator, the A circuit pin, is a dedicated battery voltage sense line.
-------------------------------------
  • Charging system malfunction (high or low system voltage)
  • possible causes:
    • A circuit 35 (OG/LB).
    • A circuit fuse link.
    • B+ circuit 36 (YE/WH).
    • B+ circuit fuse links.
    • Generator.
    • PCM
    • GEN-COM circuit 586 (RD/PK).
    • GEN-MON circuit 585 (VT).
    -----------------------------------------------------------------------------------
    Generator The generator (10300) on this vehicle is monitored and controlled by the powertrain control module (PCM). The PCM monitors the voltage regulator and sends a duty cycle command back to the voltage regulator to regulate the amount of field current supplied to the generator. The generator has an internal voltage regulator. The generator and voltage regulator are installed as an assembly.
    --------------------------------------------------
    I'll send wiring diagram tomorrow.

    please rate

    May 20, 2011 | 2003 Ford Windstar

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