Question about 1990 Plymouth Voyager

2 Answers


Posted by on


2 Answers

  • Level 1:

    An expert who has achieved level 1.


    An expert who has answered 20 questions.


    An expert that has over 10 points.


    An expert whose answer got voted for 2 times.

  • Contributor
  • 40 Answers

It is the ECM (Engine Control Module) you are looking to find. It is located between the battery and the firewall it mounts on.
This is what houses the regulator and it needs to be replaced as a unit.
You can find it online for about $200+ core.

Posted on Nov 15, 2009

  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert that got 5 achievements.


    An expert who has written 50 answers of more than 400 characters.


    An expert whose answer got voted for 20 times.

  • Expert
  • 123 Answers

Hope this is helpful, Ian

The charging system consists of:
† Generator
† Decoupler Pulley (If equipped)
† Electronic Voltage Regulator (EVR) circuitry
within the Powertrain Control Module (PCM)
† Ignition switch (refer to the Ignition System section
for information)
† Battery (refer to the Battery section for information)
† Battery temperature sensor
† Voltmeter (refer to the Instrument Cluster section
for information)
† Wiring harness and connections (refer to the
Wiring section for information)
† Accessory drive belt (refer to the Cooling section
for more information)
The charging system is turned on and off with the
ignition switch. The system is on when the engine is
running and the ASD relay is energized. When the
ASD relay is on, voltage is supplied to the ASD relay
sense circuit at the PCM. This voltage is connected
through the PCM and supplied to one of the generator
field terminals (Gen. Source +) at the back of the
The generator is driven by the engine through a
serpentine belt and pulley or decoupler pulley
The amount of DC current produced by the generator
is controlled by the EVR (field control) circuitry
contained within the PCM. This circuitry is connected
in series with the second rotor field terminal
and ground.
A battery temperature sensor is used to sense battery
temperature. This temperature data, along with
data from monitored line voltage, is used by the PCM
to vary the battery charging rate. This is done by
cycling the ground path to control the strength of the
rotor magnetic field. The PCM then compensates and
regulates generator current output accordingly to
maintain system voltage at the targeted system voltage
based on battery temperature.
All vehicles are equipped with On-Board Diagnostics
(OBD). All OBD-sensed systems, including EVR
(field control) circuitry, are monitored by the PCM.
Each monitored circuit is assigned a Diagnostic Trouble
Code (DTC). The PCM will store a DTC in electronic
memory for certain failures it detects. Refer to
On-Board Diagnostics in the Electronic Control Modules(
MODULE - DESCRIPTION) section for more DTC
The Check Gauges Lamp (if equipped) monitors:
charging system voltage, engine coolant temperature
and engine oil pressure. If an extreme condition
is indicated, the lamp will be illuminated. This is
done as reminder to check the three gauges. The signal
to activate the lamp is sent via the PCI bus circuits.
The lamp is located on the instrument panel.
Refer to the Instrument Cluster section for additional
The Electronic Voltage Regulator (EVR) is not a
separate component. It is actually a voltage regulating
circuit located within the Powertrain Control
Module (PCM). The EVR is not serviced separately. If
replacement is necessary, the PCM must be replaced.
The amount of DC current produced by the generator
is controlled by EVR circuitry contained within
the PCM. This circuitry is connected in series with
the generators second rotor field terminal and its
Voltage is regulated by cycling the ground path to
control the strength of the rotor magnetic field. The
EVR circuitry monitors system line voltage (B+) and
battery temperature or inlet air temperature sensor
(refer to Battery Temperature Sensor or Inlet Air
Temperature Sensor for more information). It then
determines a target charging voltage. If sensed battery
voltage is 325 mv or lower than the target voltage,
the PCM grounds the field winding until sensed
battery volage is 325 mv above target voltage. A circuit
in the PCM cycles the ground side of the generator
field up to 250 times per second (250Hz), but
has the capability to ground the field control wire
100% of the time (full field) to achieve the target
voltage. If the charging rate cannot be monitored
(limp-in), a duty cycle of 25% is used by the PCM in
order to have some generator output. Also refer to
Charging System Operation for additional information.
The electronic voltage regulator is not a serviced
separately. If replacement is necessary, the PCM
must be replaced.

Posted on Jul 30, 2009

  • Ian Percy Jul 30, 2009

    Does not drive generator

    (Generator not Charging)

    Clutch failure Replace Decoupler

  • Ian Percy Jul 30, 2009




    The PCM incorporates a Battery Temperature Sensor

    (BTS) on its circuit board.


    The PCM uses the temperature of the battery area

    to control the charge rate. This temperature data,

    along with data from monitored line voltage, is used

    by the PCM to vary the battery charging rate. The

    system voltage is higher at cold temperatures and is

    gradually reduced as temperature around the battery


    The function of the battery temperature sensor

    (BTS) is to enable control of the generator output

    based upon ambient battery temperature. As battery

    temperature increases, the charging rate should

    decrease. As battery temperature decreases, the

    charging rate should increase. The sensor functions

    similar to the ECT sensor with one major difference,

    the ambient sensor does not have a dual temperature

    range program. The PCM maintains the optimal output

    of the generator by monitoring battery voltage

    and controlling battery voltage to a range of

    13.5-14.7 volts based on battery temperature.

    The battery temperature sensor is also used for

    OBD II diagnostics. Certain faults and OBD II monitors

    are either enabled or disabled depending upon

    the battery temperature sensor input (example: disable

    purge and EGR, enable LDP). Most OBD II

    monitors are disabled below 20°F.


    The battery temperature sensor is not a serviced

    separately. If replacement is necessary, the PCM

    must be replaced.



    The generator is belt-driven by the engine. It is

    serviced only as a complete assembly. The generator

    produces DC voltage at the B+ terminal. If the generator

    is failed, the generator assembly subcomponents

    (generator and decoupler pulley) must be

    inspected for individual failure and replaced accordingly.


    As the energized rotor begins to rotate within the

    generator, the spinning magnetic field induces a current

    into the windings of the stator coil. Once the

    generator begins producing sufficient current, it also

    provides the current needed to energize the rotor.

    The Y type stator winding connections deliver the

    induced AC current to 3 positive and 3 negative

    diodes for rectification. From the diodes, rectified DC

    current is delivered to the vehicles electrical system

    through the generator, battery, and ground terminals.

    Noise emitting from the generator may be caused


    Worn, loose or defective bearings

    † Loose or defective drive pulley (2.4L) or decoupler


    † Incorrect, worn, damaged or misadjusted drive


    † Loose mounting bolts

    † Misaligned drive pulley

    † Defective stator or diode

    † Damaged internal fins



1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya Mechanic can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repair professionals here in the US.
click here to Talk to a Mechanic (only for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

2 Answers

1999 plymouth grand voyager voltage regulator

Not all bench tests on alternators are reliable. That battery has to be brought back to a full charge. It could be a simple connection to the alternator. Check those battery cables as well make sure the ground wire is secure.

Apr 22, 2014 | 1999 Plymouth Voyager

1 Answer

1998 plymouth grand voyager adjusting alternator charging level

Good alternator should charge 14.5+V.How old is battery,older getting weaker.

Apr 24, 2013 | 1998 Plymouth Voyager

1 Answer

1994 E150 van ford no alt power have changed the alt. charged the batt

There is a fuse or fuseable link between the alt and battery, and the alt gets a signal from the key to activate the voltage regulator.
I would check for batt voltage at the alternator and you may need a wiring diagram to check for key voltage.

Jul 02, 2012 | Ford Cars & Trucks

1 Answer

1990 dodge truck new alt. still won,t charge

Your truck uses an external regulator. I would change that part. It is located Under hood, center, rear engine area, mounted on upper firewall

and looks like this:


Feb 26, 2011 | 1990 Dodge D150

1 Answer

I have a 1993 jeep grand cherokee. its not charging. i've had the alternator and battery tested they're good. is it the voltage regulator? if so how do I change it? where is it? or can it be something else...

How can the Alt and Battery be good, but not charging? The Voltage Regulator is inside the alternator. Keep out of the Parts Store and take it to a shop and have it checked on the truck. you may have wiring issues.

May 14, 2010 | 1993 Jeep Grand Cherokee

1 Answer

Voltage fluxuations. I've replaced the alternator twice and the battery is new yet the alternator is not charging the battery. As a result the battery voltage goes down until it finally is drained. What...

check for open wiring first around the alt. sometimes will tear the insulator and arc off.You can see this at night in the dark.Most regulators are in the alternator.

Sep 25, 2009 | 1991 Plymouth Grand Voyager

1 Answer

1990 Nissan Pulsar charging problem

The alternator it self is bad internal not the regulator!

Mar 14, 2009 | 1990 Nissan Pulsar

3 Answers


In this year , there may be an external VOLTAGE
REGULATOR .Instead of an internal regulator inside the alternator. It is usually a square box to the passenger side attached to the fender inside wall. Try replacing this box with a known good one. Or new one if you can get it right away.

Dec 22, 2008 | 1990 Mitsubishi Mighty Max

1 Answer

1990 nissan se charging problems

check the power wire from the alt and check all of the grands on the car

Jul 08, 2008 | 1990 Nissan Maxima

Not finding what you are looking for?
1990 Plymouth Voyager Logo

487 people viewed this question

Ask a Question

Usually answered in minutes!

Top Plymouth Experts


Level 3 Expert

77499 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22306 Answers

Jeffrey Turcotte
Jeffrey Turcotte

Level 3 Expert

8826 Answers

Are you a Plymouth Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides