Burning fuseable link on firewall after alt. swap

Cornfield creations · Sep 23, 2010

I just installed my cs-144 alternator. Went pretty good and everything works.

But now again it burned off the fuseable link on the firewall. Like it did when I have a slightly higher amp alternator before. I switched it back to the factory unit and it didn't do it again.

At idle with both fans running and a/c on full blast it is pumping out 16.42 volts, and never dropped down. I thought these are supposed to regulate.

It's the 94 trans sport with rear a/c alternator. Any one else have this problem?

Cornfield creations · Sep 23, 2010

My adaptor plug does not have resistors built in. I got the ec80 plug from NAPA. Could this be the cause?

dhcomp · Sep 23, 2010

16+ volts!? Lucky that fusible link is there, or you would have bigger problems.

No idea why it's not regulating though. Curious to see what people say.

Cornfield creations · Sep 23, 2010

Yeah 16 and never budged off that. I thought it would go down after a bit, but it burned off the link and I shut it off.

I did read on another site about the brown wire requiring a 35 ohm resistance min. on the CS alt. I am not sure how that plays into the part of having that much voltage.

Fordum · Sep 23, 2010

Sounds like it is not sensing the voltage.
I know that when you put some alts in a truck with no alternator warning light, you have to put a resistor in the circuit to take the place of the light bulb.
Sounds like you need the resistor.

Cornfield creations · Sep 23, 2010

Ok, after I read. The brown wire on the cs model alternators need a resistance of 35-150 ohms. I had 12. I placed a 47 ohm resistor in=between the connectors and started it up. Well it finished off the fuseable link. I got disgusted and let it set.

An hour later I put my meter on the firewall block and started it up. I had a consistent 14.5 volts. On the stud of the alt. I had 14.9. So I proceeded to replace the link. Started it once again. Same voltage as before. Great!!

Load test- stereo on, both electric fans and a/c on full blast. Dropped down to 12 volts, then jumped back up to 14.5-14.9 just as before.

I let it run a while and watched it. Then I shut everything off at once, and it didn't spike but maintained same voltage.

So it works now!