Mechanics

CHARGING SYSTEM

1999 Chrysler Concorde • FWD Automatic •

I have a 99 chrysler concorde 2.7 that is not charging the battery. Note car has new bat. And alt. And the wires are all good. I understand that the power from the alt. Is regulated through the pcm and can cause this problem. Is there a safe way of bypassing this and still safely charge the battery.
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Jakethesnake2
January 25, 2011.




Yes, there's a simple modification, but you should know that Chrysler has very little trouble with their voltage regulator circuits.

The first thing to do is to measure the voltages on the two small wires on the back of the alternator and the large output wire. The output wire must have full battery voltage all the time. If it is missing, look for a blown large fuse in the under-hood fuse box.

One of the small wires must have full battery voltage and the other one must have less but not 0 volts. That one is the key to diagnosing the system. Those two voltages will only be there when the engine is running, not just with the ignition switch turned on. Let me know what you find.

Caradiodoc

Caradiodoc
Jan 25, 2011.
Going to work on car really soon. I will check all other things you talked about and see if maybe the fuse is blown. The person I bought the car from said it would probally need to be bypassed. How do you go about bypassing the voltage regulator? Can I simply run a new wire with a fusable link straight from alt to bat or is there another way you have to do it.

Tiny
Jakethesnake2
Jan 26, 2011.
It involves installing an electronic voltage regulator from the 1970s. The Engine Computer will detect that no current is flowing through its built-in regulator and will set the diagnostic fault code "field not switching properly" in memory and turn on the Check Engine light. At that point you will never know when a different problem is detected because the light will always be on. You might be able to solve that by adding a resistor to take the place of the missing field coil but I never tried that. It seems to me if that would work, it would also work running the alternator like it is supposed to.

Caradiodoc
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Caradiodoc
Jan 26, 2011.
I ran a direct line from alt to bat with a 20 amp fusable link in it. It is charging properly and has not blown any fuses so far. Will a simple fusable link be enough to protect the other electronics and my new battery.

Tiny
Jakethesnake2
Jan 27, 2011.
Which wire on the alternator? There's three of 'em. Which battery terminal? There's two of 'em. If you ran a wire from the battery positive to the large alternator output wire, the fuse will blow as soon as the system demands more than 20 amps, which is pretty soon. It takes 10 - 15 amps to run the fuel pump, injectors, ignition coils, and computers. Add brake lights, heater fan, head lights, (pop), and we haven't even talked about recharging the battery yet.

If the wire goes from the battery positive to the orange / dark green wire, you bypassed a 20 amp fuse "T" in the under-hood fuse box.

If the wire goes from the battery negative to the dark green wire, you bypassed the voltage regulator in the Engine Computer. That will lead to overcharging the battery and popping light bulbs and computers. This is how the "full-field" test is performed when testing an alternator. Damage will start to occur when you increase engine speed. If you measure battery voltage, it must be between 13.75 and 14.75 volts. If it is higher than that, and if it goes higher when you raise engine speed, you're going to start damaging stuff.

Caradiodoc

Caradiodoc
Jan 27, 2011.
Positive battery to large alternator output wire. Has not blow fuse. Is this the line that I will need to put the voltage regulator in.

Tiny
Jakethesnake2
Jan 28, 2011.
Solved. There is supposed to be voltage on that output wire all the time. If it only charges when you have that jumper wire installed, you have a blown fuse. Modifying the circuit with an external voltage regulator isn't going to solve that. Look for a large fuse that is bolted in the under-hood fuse box.

Caradiodoc

Caradiodoc
Jan 28, 2011.

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