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 Post subject: 18v alternator voltage
PostPosted: Mon Sep 19, 2016 6:48 pm 
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Some call me a god

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Location: Toronto Canada
Just swapped a 4g63t into my 88 sedan. Motor was running well before. Now its running well, but too high a voltage.
Any ideas?
I have to try to add a ground at the alternator.
Next step is to take the alternator out and have it tested.
The fusible link at the battery gets really hot and starts smoking from only a minute of running.
I may also try to run a dedicated set of wires from alternator to battery and add an 80amp fuse like on the dsm.
Currenlty running the stock colt wires.

88colt has a slightly different alternator wiring. No actual fuse at the battery and it doesnt use a diode/relay.

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DRCOLT
1989 3g Colt GT turbo w/4g63t
1988 2g Colt sedan turbo w/4g63t +++++


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PostPosted: Mon Sep 19, 2016 6:53 pm 
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DRCOLT
1989 3g Colt GT turbo w/4g63t
1988 2g Colt sedan turbo w/4g63t +++++


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PostPosted: Mon Sep 19, 2016 7:40 pm 
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2nd Banana
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Replace the alternator. Should fix the problem

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PostPosted: Mon Sep 19, 2016 8:07 pm 
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I just went back out to test the alternator output voltage on its own disconnecting the white wire at the alternator b terminal. I read 68vdc.
No wonder the fusible link is cooking.
Maybe I fried the regulator the first time it was connected as the colt alternator.
Tomorrow I am going to test my other 89 colt's voltage.

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DRCOLT
1989 3g Colt GT turbo w/4g63t
1988 2g Colt sedan turbo w/4g63t +++++


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PostPosted: Tue Sep 20, 2016 10:46 am 
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The Silent Administrator
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That voltage can be enough to fry the ECU.

Like Tony says, install a new alternator and see what happens. The regulator is built in and should never reach that high a voltage. Have someone start the car when it is first installed and monitor voltage right off the bat. Voltage should be no more than 15.4 at super low temps, to about 13.5-13.2 loaded and warm.


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PostPosted: Tue Sep 20, 2016 8:11 pm 
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Location: Toronto Canada
Droped it off at a local shop. Lets see what he finds.

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DRCOLT
1989 3g Colt GT turbo w/4g63t
1988 2g Colt sedan turbo w/4g63t +++++


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PostPosted: Wed Sep 21, 2016 11:13 am 
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The Silent Administrator
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If at all possible, find a Mitsubishi replacement regulator/diode assembly. All other fail in shorter order than they should with minimal cooling to the alternator in the engine bay. They are expensive but I've been reading too many stories about rebuilds and new (all non-OEM), that give up the ghost rather quickly. Hopefully your shop can get you parts that will do the electrical system some justice. Shouldn't have to add any grounds directly at the alternator case to chassis or battery ground, just a regulator assembly that works should bring it all back into spec. Hopefully the alternator doesn't have any shorts in the windings and such.


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PostPosted: Wed Sep 21, 2016 1:10 pm 
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Regulator was blown. Rebuilt now and ready to install.

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DRCOLT
1989 3g Colt GT turbo w/4g63t
1988 2g Colt sedan turbo w/4g63t +++++


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PostPosted: Wed Sep 21, 2016 8:22 pm 
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Reinstalled and running well.

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DRCOLT
1989 3g Colt GT turbo w/4g63t
1988 2g Colt sedan turbo w/4g63t +++++


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PostPosted: Thu Sep 22, 2016 11:17 am 
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The Silent Administrator
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Glad to hear it!


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