How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask sprinkles08 Your Own Question
sprinkles08
sprinkles08, ASE Certified Technician
Category: Jeep
Satisfied Customers: 22979
Experience:  Chrysler/Dodge/Jeep Master Certified, ASE Master and Advanced Certified, Trans and Hybrid Specialist
9825021
Type Your Jeep Question Here...
sprinkles08 is online now
A new question is answered every 9 seconds

2012 jeep grand cherokee 3.7liter alternator not charging

Customer Question

2012 jeep grand cherokee 3.7liter alternator not charging replaced with new alt still no charge ck all fuses
Submitted: 1 year ago.
Category: Jeep
Expert:  david craig replied 1 year ago.

Hi Im David, what is the voltage reading at the alternator?

Customer: replied 1 year ago.
10volts at the battery wire.
Expert:  david craig replied 1 year ago.

10 volts at the battery cable on the alternator while the car is running?

Expert:  david craig replied 1 year ago.

I need you to check the voltage at the large cable on the alternator while the vehicle is running. let me know the results and we can go from there. Thanks.

Expert:  david craig replied 1 year ago.

hello?? do you still need assistance?

Customer: replied 1 year ago.
I have 12 plus volts I needed to recharge battery
Expert:  david craig replied 1 year ago.

at the alternator what is the voltage?

Customer: replied 1 year ago.
12 At the alternator the voltage drops as the battery discharges
Expert:  david craig replied 1 year ago.

replace the alternator. problem solved

Customer: replied 1 year ago.
I replaced the alternator twice problem not solved
Expert:  david craig replied 1 year ago.

i see where you say its been replaced, not unheard of to get a bad "new" part. did you check the connection on big cable from alternator to battery? for corrosion and looseness?

Expert:  david craig replied 1 year ago.

do you have access to another battery?

Expert:  david craig replied 1 year ago.

you can also check the cables at the starter to make sure they are clean and tight. on your vehicle, the positive cable runs from the battery to the starter then from the starter to the alternator

Expert:  david craig replied 1 year ago.

there is also a fusible link in line with the battery positive cable. check that and make sure its not all soft and mushy

Expert:  david craig replied 1 year ago.

hers a print for ya

Customer: replied 1 year ago.
I replaced it twice its defiantly not the alternator but I'll come the wiring diagram and fusible links
Expert:  david craig replied 1 year ago.

try a different battery if there is nothing wrong with the cables

Customer: replied 1 year ago.
Brand new battery has been installed.
Customer: replied 1 year ago.
Could the computer cause it to not charge?
Expert:  david craig replied 1 year ago.

sure. look at the print. right from the pcm.... but the main concern for me right now is corrosion on the cacles or under the insulation causing resistance that results in voltage drop

Customer: replied 1 year ago.
Checked fusible link cked wiring all good what kind of current should I have at alt plug one is ground nothing on other wire in plug
Expert:  david craig replied 1 year ago.

thats the internal voltage regulator hang on a few.....

Expert:  david craig replied 1 year ago.

The three-pin multiple plug has no earth terminal. Switch on the ignition and test the continuity of the leads one by one, by connecting them with the voltmeter to an earth. You should get a reading of battery voltage for each one; if not, there is a broken connection and the alternator cannot change the battery. if there is only 2 wires in the connector then there should be another small separate wire

Customer: replied 1 year ago.
There's only 2 wires in the connector and 2 pins in the alternator I don't see a third wire the wire colors are green and red, brown and red
Expert:  david craig replied 1 year ago.

ok. allow me a few to look into this

Expert:  david craig replied 1 year ago.

apparently The voltage regulator is inside the pcm,he amount of DC current produced by the generator is controlled by EVR circuitry contained within the PCM. This circuitry is connected in series withthe generators second rotor field terminal and its ground.

Voltage is regulated by cycling the battery voltage to control the strength of the rotor magnetic field. The EVR circuitry monitors system line voltage(B+) and battery temperature (refer to Battery Temperature Sensor for more information). It then determines a target charging voltage. If sensed batteryvoltage is 0.5 volts or lower than the target voltage, the PCM energizes the field winding until sensed battery voltage is 0.5 volts above target voltage. A
circuit in the PCM cycles the battery side of the generator field up to 100 times per second (100Hz), but has the capability to full field to achieve thetarget 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.

Customer: replied 1 year ago.
I said it was a 3.7 it's a 3.6 liter just realized it my fault
Expert:  david craig replied 1 year ago.

you know theres a recall for your veicle for faulty electrical problems caused by the alternators? #14V634000

Customer: replied 1 year ago.
I didn't know that there was a recall but I'll ck into it
Expert:  david craig replied 1 year ago.

ok. other than if they find something when they do the recall, the only possible thing that could be going on is the ecm. it wouldnt even be a fuse since the pcm controls the output voltage...please dont forget to rate my service as its the only way i get credit for helping. thanks. have a good one

Customer: replied 1 year ago.
Ck dealer they say there is no recall per Vin number can u ck the recall num again please
Expert:  david craig replied 1 year ago.

ok

Expert:  david craig replied 1 year ago.

Recall Number

14V634000

Recall Date

10/08/2014

Component

ELECTRICAL SYSTEM:ALTERNATOR/GENERATOR/REGULATOR

Summary

Chrysler Group LLC (Chrysler) is recalling certain model year 2011-2014 Chrysler 300, Dodge Charger, Challenger, and Durango; and 2012-2014 Jeep Grand Cherokee vehicles manufactured April 22, 2010, to January 2, 2014, and equipped with a 3.6L engine and a 160 amp alternator. In the affected vehicles, the alternator may suddenly fail.

Consequence

If the alternator fails, the vehicle may stall without warning, increasing the risk of a crash.

What Owners Should Do

Chrysler is expected to begin notifying owners of this recall on November 28, 2014. The remedy for this recall campaign is still under development. Owners may contact Chrysler customer service at 1-***-***-****. Chrysler's number for this recall is P60.

Read more at https://www.cars.com/recalls/jeep-grand_cherokee-2012/#ze3vBJW1wkpbKKz3.99

Expert:  david craig replied 1 year ago.

hello? do you still need assistance?

Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

Do you still need help?