I have been struggling with rough idling, misfiring, and low voltage for the past week and a half in my 1998 Jeep Grand Cherokee Laredo. It started out misfiring and voltage dropping, and the check engine light came on, so I borrowed a friend's code reader and it said faulty crank position sensor, bad connections, and check charging system. I checked my crank position sensor, and it was covered in oil, so I cleaned it off, and it hasn't been misfiring quite as bad. I changed my spark plugs, distributor cap and rotor, had my battery charged overnight at Advance Auto, and tested the next day and they said it was fine. I took my battery home and put it in my car and immediately my voltage gauge read only about 11 amps. I don't think it's the alternator, because i replaced it in April, and the battery read low as soon as I put it in my car, indicating what I think would either be a connection problem or a battery problem, but not a charging problem. im stumped and very frustrated.
Hello - the first thing to check is the electrical system voltage with the engine running at a fast idle - which should be 13 volts or above. Check this with a known good voltage meter - auto gauges are notoriously inaccurate. If system voltage is low, the voltage regulator or alternator are suspect, and should be checked and replaced as appropriate. Bad battery connections will degrade system performance somewhat as well. I would recommend having a Battery Light is On inspection completed by a mobile, professional mechanic, such as one from YourMechanic. They can come to your location, diagnose this problem, and give you an accurate assessment of damage and cost for repairs.
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