Voltage Spike

Shouldn't make a difference. The voltage regulator will only let the alternator make as many amps as necessary. No difference in wiring between the two.

 

Yup. Voltage output should be the same between the 2.

 

Is this with the truck running? Should be reading around 14v with truck running . Around 12v with truck not running (battery)

 

Solved!

Here's what happened. I redid the terminals, with solder, jackets, and better crimps. After that I decided to retest the wires that connect to the alternator...

White wire which connects to the ALT-S fuse in the engine bay now showed me .13 volts. This was with the negative probe on the battery and positive touching the pin side of the connector. This was way off from the first reading I took.

I then tested the fuse the same way, 12.3v... I then spiced right after the white wire coming out of the fuse block and took a reading there, 12.25v, so now I knew somewhere between after the fuse box to the connector something was wrong.

Spliced open the wiring right before the connector and made my own connection with leftover wire I had from the LEDs I put in my Evo. Took another reading and got the 12.25v, awesome! Now I nicely cut the wiring, used some crimp connections, put everything back together and now I'm getting a steady reading coming from the battery with the car running of 14.49.

What's weird is that before the white wire did test fine at around 12.23v, but the battery charge was not steady instead it was between 14.8 to 15.4v... maybe it was the terminals that gave me a better reading?

So that's pretty much it. As of now the issue is solved and no more battery light.

My symptoms:
Car running, battery read 14.8 to 15.4v
Battery light would flash on the dash and the battery gauge would spike up
Alternator tested bad on the car, but tested good on a bench test

Hope this helps someone out there

 

Nice job way to stay after it and not give up

 

I am having the same issue. I replaced alternator with a HO alternator from JS alternators and still having high spikes. Did you replace the white wire completely?

 

I am also curious about this. I've been using a Mechman for over a year and suddenly started getting these spikes. I suppose I'll dissect my fuse box harness and run another wire to the alternator.