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Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 8622
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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Mitsubishi outlander: I have a 2003 Outlander that is overcharging

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I have a 2003 Outlander that is overcharging and won't start. I replaced the alternator but did not fix problem. What else could it be?



You said that it won't start, but it's over charging... Can you elaborate on the condition, as to how we know it is over charging... what it does when you try to start, and so forth.

Customer: replied 4 years ago.

It will start but overcharges to 26 volts


Can we verify that meter is reading correctly on another vehicle? While certainly possible, 26 volts should pretty much destroy the entire electrical system in a few seconds. Anything over 16V-17V will fry your computer in seconds time.
Customer: replied 4 years ago.

This is what my mechanic is telling me

I understand.

There are a few things to consider here, assuming that reading is correct:

First, you nearly can not use aftermarket alternators on these cars. This particular design uses dual regulation, an internal regulator and external control via the PCM (computer). While there are some out there that work, most aftermarket alternators are not built to accommodate this, as they are simply rebuilt with off the shelf parts and this particular design is specific to this product line only.

Second, as above mentioned the dual regulation, just because the car is over/under charging does not necessarily mean the alternator is at fault, since it is externally controlled by the PCM.

If the voltage reading is confirmed (meter reads 12V-14V on a different car), then we have two things to take care of. If the alternator was replaced with aftermarket, get it out of there before it does any damage. Again there are some out there that work, but the majority do not and they DO cause major problems. NAPA and Duralast are the absolute worst offenders, I have seen many of both brands destroy computers right out of the box.

Once the alternator is replaced with a proper Mitsubishi alternator it can be checked again to see if the charging is still messed up. If it is (or if it was replaced with a Mitsubishi alternator), then unusual circumstances aside (rodent damage to wiring etc), the PCM will be at fault as nothing else is involved in voltage regulation.

Never the less, the PCM can be tested to verify operation as well. On the back of the alternator is a plastic electrical connector with four wires in a row.
If wire one is probed for voltage with the key on (preferably running but not necessary), the voltage should start at or near 0 and slowly increase as loads are added (turning on the headlights, AC fan, etc).
If wire four is probed for voltage with the key on, the voltage should start near 5V and slowly decrease as loads are added.

If either of those tests fails, verify the wiring is not damaged anywhere, and if not replace the PCM.

I would strongly recommend putting a factory alternator on there first though if it is aftermarket.... they honestly have about a 1/100 success rate, but due to being used on other more common vehicles (Hyundai) that do not require the PCM control to work they are not "corrected" when they get built wrong. The odds of the aftermarket alternator being the cause of the over charge is much much higher than the odds of the PCM being bad, excluded the potential for the alternator to damage the PCM of course.
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