A battery saver message can come up on a 2014 Grand Cherokee with the 3.6 a few days after a new battery went in, and the headlights look dimmer at a stop than they did last month. Dim lights and that message are signs of low charging output, and a fresh battery cannot fix low output. It simply gets used up faster. Charging it is the alternator's job, and the alternator runs off a belt and powers the vehicle while the engine turns.
The question to settle is what the alternator delivers with the engine turning, so we measure its output at the battery with the loads switched on and send the repair to the alternator or the belt that falls short. On the WK2 Grand Cherokee, built for the 2011 through 2021 model years, the 3.6 Pentastar V6 and the 5.7 V8 both turn the alternator with the serpentine belt, the single belt that also drives the other accessories. We take that reading for drivers from Oakland at Precision Auto Care in San Leandro.
Why Did the New Battery Go Flat?
With the engine running, the alternator is supposed to carry every electrical load in the vehicle and refill the battery at the same time. Any shortfall comes out of the battery's stored charge. That battery saver message is the cluster showing that the vehicle is drawing that charge down. Not every failure brings up the message, so a Grand Cherokee may go flat without ever showing it. When the alternator is not putting charge back, a new battery lasts only as long as its stored charge.
Inside the alternator, a set of diodes, each a one-way electrical part, turns its output into current the battery can take. On a 2012 through 2014 Grand Cherokee with the 3.6, a failed diode drops output to nothing or cuts it partway, and it can short to ground as well. When output drops partway, the Jeep still starts and runs while the battery charge keeps falling. A complete diode failure on those model years with the 3.6 stops the alternator supplying power, and the engine can stall without warning. If the charging warning comes on with dimming lights, heavy steering or stalling, get off the road safely and have it towed rather than driving on.
What Are the Whine and the Flicker?
Headlights and dash lights dim, and power windows move slower than usual. On a 2012 through 2014 Grand Cherokee with the 3.6 and electro-hydraulic power steering, the steering can feel heavy as well, because the steering assist runs on that same electrical supply. Those are signs rather than proof, since a weak battery produces a similar flicker. Worn bearings inside the alternator make a grinding or whining noise under the hood. A burning-rubber smell can come from a slipping serpentine belt, and a slipping belt turns the alternator slower and cuts its output.
Which Part Is Falling Short?
We measure the voltage at the battery with the engine running. A working charging system holds about 13.5 to 14.5 volts there and recovers to that range when the loads come on. Near 12 volts, the battery is not being charged at all. If output is low and the belt is sound, we repair the alternator. With a slipping belt, we repair the belt first. Alternators on the 2012 through 2014 3.6 left the factory rated at 160, 180 or 220 amps, and the replacement has to match the rating the vehicle was built with.
Your estimate then names the part that tested weak and the repair we will make. After the charging repair, we test the battery itself, because a battery run flat by a charging fault can be left weakened. When it tests weak, we install an Interstate Battery.
Schedule a Charging Test in San Leandro
Call Precision Auto Care in San Leandro at (510) 351-8211, and let us know which message came up on the cluster and how many days the new battery lasted. At your visit, we measure the charging output at the battery with the engine running and the loads switched on. The repair then goes to whichever part came up short, the alternator or the belt.
