Floorman279

iTrader: (11)

i have a 427 in my 2000 camaro.....like most when it was a HCI ls1, i put in a used 4 prong gm truck 160 amp alt that i got from ebay. worked great, now check gauges light. put the 427 in, noticed severe volt drop on the gauge, read about 11-12 volts. as soon as i stopped the pull the gauge went back above 13. so i did the big 3 upgrade. same results. so i ordered a mechman truck alternator with larger pulley, installed it, voltage drop went away during pulls.

now despite it charging well according to the gauge, very shortly after i installed the mechman, i now have a check gauges light, and the light is getting annoying. all gauges are fine tho. i dont recall if it was there immediately after install, but if it wasnt it definately appeared within 25-50 miles. i used the supplied single wire exciter wire, spliced it into the harness and connected to alternator. now a few questions. another kicker is after install, i got a call about 2 weeks later from the alternator supplier, asking if the alternator was not installed could they have it back becuase they mistakenly sent me a much more expensive black case marine alternator. since i had already installed it, they said keep it.

1)with a tech 2 can you confirm that all is well with the exciter wire? im curious if for whatever reason maybe they gave me the wrong single wire and its connected into the wrong prong on the alt? extremely far fetched

2)i have read that the C6 is very picky with regulators in the alternator. some parts store alts will throw service charging on those because they throw in a truck regulator rather than a proper c6. is the 4th gen picky on this too and is it possible the regulator inside this marine alternator is making it unhappy?

3)is it the different pulley size causing issues at idle despite charging fine?

any help appreciated, i want this check gauges light off. again,oil is about 38 at idle, coolant temp is a needle width below 210, and fuel gauge has been sticking towards full lately but once i do about 100 miles the fuel gauge begins to read. im thinking the regulator in the new alt isnt agreeing with the car

Full Power

Take off YOUR alternator, have local rebuild shop put in a ONE-WIRE self excite regulator. ( Regitar # D235SEL)
While it's there have them put a larger diameter pulley on to slow the rotor down.
( I use a 68 mm diameter, Alternator still makes 90 amps at low idle )
Cheap, easy, and never worry about it again.

Floorman279

iTrader: (11)

it is a single wire, and my mechman already has a larger pulley....im confused as to where you are getting at.....are you saying take a stock gm alternator and rebuild it to put out more amps?

Full Power

No reason to 'rebuild' a new or functioning unit.
I was suggesting that you just replace the Voltage Regulator, it is located under the plastic cover, back of Alternator.
If you eliminate the need for an ignition excite wire it will simplify your system.
ONE single charge wire, around 8 gauge should do the job.
No need to confuse your ECM with Alternator signal.
. Larger diameter pulley would be installed to SLOW down alternator, less belt slippage on accel, and less drag at high RPM.
.
I went with the biggest 6 rib pulley I could find, and still get rated 145 amps at 1400 rpm.
90 amps at 650 RPM idle, plenty of power, lower Alternator speed, less belt slip on 6500 RPM 1-2 shift.

Floorman279

iTrader: (11)

so why are you recomending replacing the regulator? how do we even know the regulator in the mechman is incorrect

Full Power

.
. OP was describing intermittent charging system shutdowns. ECM is controlling the "Marine Spec" Alternator via excite wire, and throwing codes.

I was just offering a simple, inexpensive, easy to implement solution. OP already owns two functional alternators, either one easily modified for ONE WIRE service.
.
By eliminating the ignition EXCITE wire, the car's ECM will have no connection to the Alternator voltage regulator.

The ECM will not be able shut down alternator at high rpm and/or high load conditions.

ONE wire alternator connection solves or eliminates chassis/computer/ wiring issues.

ONE drive belt turns alternator.

ONE 8 gauge wire charges battery.

Simple solution.

JimMueller

iTrader: (9)

I've got a Mechman 8206250 in my Fbody. I recall the instructions saying that a dash light would come on if we didn't use their custom wiring. I recall we used their custom wiring harness and connected via add-a-circuit to the fuel pump circuit. That caused a trickle discharge, so we moved it to the PCM circuit and all has been well for perhaps a year. Did you need to do all of that with your Mechman truck alternator?

Floorman279

iTrader: (11)

i dodnt recall reading instructions....woops.......whatand how did you connect to the pcm circuit

JimMueller

iTrader: (9)

I'm notoriously OCD about keeping receipts & instructions, but for whatever reason I cannot locate my hard copy of the directions they included. I do not know if the following applies to your specific Mechman alternator (as it explictly states it is for their S- and E-series), perhaps speaking with their tech support would be best.

This link describes the adapter harness needed to disable the false warning on the instrument cluster. The colors in this diagram are for a standalone harness sold separately; the harness that came with my alternator had different wire colors but was functionally equivalent.
https://www.mechman.com/technical-re...n-alternators/

This is where I have it connected to the PCM IGN fuse:
https://www.dropbox.com/s/d8g2oq2lmn...24452.jpg?dl=0

Floorman279

iTrader: (11)

thx jim. im at the point in my life im tired of tinkering and that car will be in the shop within the next couple months. if i have any more questions ill let u no. but thanks for the image

Floorman279

iTrader: (11)

thanks jim, did the add a circuit like you did and turned the light off

FirstYrLS1Z

iTrader: (4)

I'm mechanically inclined but not electrically inclined.
The 'exciter' wire, what does it do ?, what is its' purpose ?.Based on posts in this thread, it's not necessary. What would happen if it was 'broken'/incomplete circuit ?

wssix99

iTrader: (5)

I'm not an expert, but my understanding:

Alternators need the exciter wire to induce a magnetic field in the core of the alternator so it can start up and produce the proper level of voltage. Unlike a generator that has permanent magnets surrounding it, the alternator needs this help to become an electromagnet. Once it gets going, it creates enough electricity to keep itself excited:



One-wire alternators hold on to residual magnetism in the core of the alternator through some paracitic draw off the battery when the engine isn't running. They use that magnetism to get the alternator going when the engine starts. These alternators do have drawbacks and are probably not a good choice for cars driven infrequently or put in long term storage.