Looking at the schematic for a tuff stuff alternator and it is showing that it needs a resistor in the small brown "Exciter" wire for the alternator. I'm trying to think way back to when I ripped my car apart and I do not remember removing a resistor at all. I looked in my gm factory manual and it does show a resistance wire on the schematic. Is it in the cluster? Is it somewhere else? Please help to clarify. Thanks in advance!
Resistor in alternator wire???
- Thread starter mc1984ss
- Start date
- Status
The resistor is generally used when there's no charge light used to energize, or excite the alternator. Do you recall having a charge light in one of your gauges? If not, you can always add an inline resistor in the brown excite wire.
I do not remember having a charge light but I could be wrong. Looking at the factory schematic some more it looks like it runs through all the other factory warning lights. It is the brown wire coming from the bulkhead connector at the firewall correct?
That resistor wire should be in the dash harness in place of the brown wire that would of ran from the bulk head to the cluster.
I normally have a pretty good understanding of electrical circuits but I have to apologise I'm still confused. So if I have the brown wire from the bulkhead going to the connector on the alternator is it going through the resistor? Does it go though the resistor wire then to the alternator? If memory serves me correctly this is how I ran my old gm alternator all those yrs ago. Thank again
In addition, I believe the factory harness also had a diode in the brown exciter wire (somewhere in IP harness). Further, 10SI and 12SI alternators are apparently extra susceptible to backfeeding through the brown exciter wire (thereby energizing the ignition switch when it should be off: resulting in motor be unable to shut off). This is common that enough Painless makes a kit for this situation. See: https://www.summitracing.com/parts/prf-30720
PS You can just use an everyday 20 cent diode rather than buying the $9 painless kit (plus S&H).
PPS I will look for schematic showing the diode.
PS You can just use an everyday 20 cent diode rather than buying the $9 painless kit (plus S&H).
PPS I will look for schematic showing the diode.
Last edited:
It'll be a brown-white stripe wire running from the bulk head (changes the circuit number from 25 to 130) to the ignition switch on the column, sharing the same spot as the orange wire for circuit 300 (both wires crimped together in the same terminal.)
I went through similar debacle when I wired in cs130 alternator. I ended up bypassing original harness completely and ran from 12v run source. I chose to be redundant and put resistor parallel to a small idiot light I mounted close to aftermarket voltmeter. I read that the brown wire is a resistor type wire but I was afraid of frying alternator because I have read they are finicky
- Status
Similar threads
