Q: Alternator and battery issues. Car has trouble starting.

asked by on

I replaced my alternator about 2 weeks ago. The alternator cannot keep the battery charged and drains it down. Initially, the battery light was coming on after driving for about a 1/4-mile and would stay on until the car was shut off. Recently, the battery light started coming on immediately upon startup and the car started dying. I replaced the battery, but soon thereafter the battery light came on again. While driving on the freeway, the motor went into LIMP MODE when I drove over 45 MPH. Once I got home, I turned the car off and tried starting again. At first it would not start, but I eventually got it to turn over.

From all the detailed description you provided me, I have been able to narrow down the problem with your Jeep to a failure with the PCM (Powertrain Control Module). It is the computer that controls the engine, as well as regulates the voltage externally for the alternator. Most alternators have an internal voltage regulator. If the voltage regulator fails, it will cause the PCM to not function properly and in turn cause the problems you were experiencing, such as the vehicle going into LIMP mode. I would next have a certified mechanic come out and verify this repair. A mechanic can confirm and repair the PCM, however your Liberty will need to visit a dealership to have the PCM reprogrammed.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Alternator and battery issues. Car has trouble starting.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: My mazda cx9 front whhel axle broke whole driving , what is the average repair cost ,

In a case like this it's difficult to estimate the damage without getting an inspection. What probably started as a bad wheel bearing became a whole lot more complicated when it was driven until failure, and it will be necessary...

Q: My car is shaking at idle and is losing power in the low end service engine soon light is flashing.

Engine misfires can be caused by many different problems and are generally caused by either a spark or fuel issue or in some cases, a combination of both. Spark related problems generally will result from things like ignition coils, crankshaft...

Q: Gas sprays out of the tank when i fill up my 06 Jeep Liberty. What are the possible causes and how much will each one cost to fix?

Hi there. In most cases when you have excessive pressure inside the fuel tank, adding gasoline will cause the symptom you've described. In other cases, it's the gasoline pump hose that is causing this problem. This is often regulated by...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...