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Discussion Starter #1
Hey guys,

Just replaced my pooched out alternator with a new rebuilt bosch/Nippon Denso unit.

It doesnt seem to be overcharging now (no where near the 18 volts it was at yesterday) but both lights are still on!! (charge and ebrake)

I was wondering if there was a reset or somthing to alleviate this problem, or if my battery is toast... possible??

The 5MGE is out of an 88 Cressida, could that cause it?

Thanks,

Aaron
 

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Discussion Starter #3
i believe the alternator I got was for the 88 Cressida... does that make any kind of difference?

Aaron
 

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My mk2 has a 86 cressida alt in it and i found that the alt light stayed on......check the alt relay down by the kick panel on the right hand side......you may need to replace this with a new one.
 

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You need to remove the charge light relay in the 82 & 83 and jumper two of the four relay socket terminals with a 1N4001 rectifier diode when upgrading to the later style alternators. That should solve the problem you're having with the charge and e-brake indicator lights staying On. As for which of the four terminals that get connected to the diode, the Anode end of the diode connects to the yellow w/white stripe wire (charge lamp filament) and the Cathode end connects to the black w/yellow stripe wire (CHARGE fuse) in the relay socket. I don't recall exactly which two of the four relay socket terminals are connected to these two wires, but the diode sits vertically in the socket after installation. The two remaining socket terminals are left unused.
HTH!!
 

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Discussion Starter #6
aa

Dave,

Cool... thanks for the info. Im guessing then that I wont have any problems driving the car as is, except for maybe the anoyance of the lights being on... correct?

Oh, and what is it about the newer style alternators that causes this to happen?

Thanks,

Aaron
 

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Aaron, no really, you have an 82 alternator, unless the new on you just got is the new style. The only thing from that cressida in your car is the block and the head, everything else is 82 spec.
 

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Discussion Starter #8
Seamus,

I know that =) I got the newer style alternator though, thats why Im wondering. It'll be safe to drive with the lights still on you think, eh?

Anywho, Im guessing that the reason im only getting 13.2volts at the battery terminals is because the battery isnt accepting a charge anymore. I cant imagine that the alternator going would cause any other sort of charging system failure... especially when Im making 14.3 at the alternator.

Aaron
 

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The 82 & 83 alternators (old style) have a different voltage regulator that is designed to work with the charge light relay. The 84 & up MKII alternators have a different design voltage regulator that doesn't require and isn't 100% compatible with the charge light relay. The charge light relay is actually more like a charge light control circuit that incorporates a PCB and a relay. On the 82 & 83, the charge light relay provides the ground path for the charge and brake lamp filaments. On the 84-86 MKII's, the voltage regulator provides the ground path. The reason for your charge and brake lamps staying On is because the later style voltage regulator in your new alternator (later style) isn't designed to work with the PCB electronics in the charge light relay and the relay is staying energized. The diode install will take care of this problem and will only set you back about 50 cents or less for the cost of the diode and 2 crimp-on spade terminals.
The relay socket looks like this with the relay removed:

I I

_ _


I'm pretty sure that the left side terminals are the two that are used with the diode and the right side terminals remain unused, but I don't recall exactly how the diode is oriented with respect to the anode and cathode? Maybe Leslie can help us out here since he has done this mod. after having to fuss with about 5 different MKIII alternators from NAPA, only to find out that the alternators were all okay and not to blame for the lamps staying On. :roll: Leaving the relay circuit installed could possibly damage the voltage regulator in your new alternator, although rebuilt alternators from NAPA seem to be the most incompatible from what I've seen so far.
HTH!!
 
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