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Doug
Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 8569
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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Mitsubishi Montero Sport XLS 4x4: Doug, .

Customer Question

Hi Doug,
My name is Jose.
Just reconditioned the alternator in my 2002 Mitsubishi Mpontero and the "battery" and "brake" warning lights remain "on". The alternator is charging and the battery is holding a charge.
Tell me please how I can turn off the warning lights, is there a way to reset the onboard conputer
Submitted: 1 year ago.
Category: Mitsubishi
Expert:  Doug replied 1 year ago.
Hi,

The battery and brake lights come on any time the system voltage is below 13V (roughly). If the lights are coming on, there is a power drop occurring somewhere. Generally speaking when we see this it is a fault of either the diode or regulator inside the alternator.

If you are certain you have good charging voltage at the alternator (at least 13.5V), then check your power at the fuse panel... there is likely a fuse popped. Specifically, we often see the large fusible link fracture to the point that it just barely passes voltage.... so if you measure at the alternator you might see 14V, and at the battery 14V, but then the rest of the car is seeing 12.8V or something like that.

Never the less... the bot***** *****ne is going to be either internal to the alternator (not the case if you have 13V+ at the alternator post) or a problem with the wiring/fuses preventing that charging voltage from reaching the rest of the car. The two lights have constant power on one side and ground on the other, when the charging voltage from the alternator reaches them it puts power on both sides to turn the lights off.... the charging voltage is not reaching the lights if they are staying lit.
Customer: replied 1 year ago.

Doug,

I am getting 14.5" volts at the battery terminals.

Tell me please where exactly I might find this "large fusible link" as there are several fuse blocks in this model. A large fuse block and several relays near the battery in the engine compartment plaus another block under the dash in the driver's side.

Jose

Expert:  Doug replied 1 year ago.
If you are seeing 14.5v that is a borderline overcharge, which will turn the lights on as well. 14.5v is pretty close, it is usually more like 14.7 but either way it's a slight area of concern.
There are two different primary fusible link designs... One that hangs of the battery positive terminal and on other models they switched it to a link in the under hood fuse box, bolted in from the bottom. In either scenario, look for the link that is in the 80-120A range.
Knowing that your voltage at the battery is considerably high, I would be a little concerned about that though. If you are seeing the same 14.5v at battery post and main fusible link, I'd still be concerned about the condition of that alternator.