Generator (alternator) wiring

[fj1289]

Question on the generator output and wiring.  Two wires exit the generator - a red and a brown.  Are both of these regulated 12 volt? (i.e. 13-15v when charging)?

Trying to figure out how to wire the generator for the dragbike project.  Last couple of alternators I've dealt with have only had a single output.  It would appear on the FJ that the two wires could be "combined" to make a single output since they are "joined" by the ignition switch on the stock harness. 

Thanks,
Chris

[andyb]

Looking at the schematic, that seems right to me.  It's DC so there's no worry about phase, and the ground is clearly shown elsewhere, so there's not much else they could be.  Both appear to go to the main switch, with one then going to the battery and the other to feed a distribution block.

[RichBaker]

Do we have a diagram online somewhere? I'm at work, don't have one handy....

[fj1289]

Andy - my assessment too.  I just want to make sure I haven't overlooked something before I try it.

Rich - I haven't been able to find one online for the FJ - just the XJR, but it shows the generator is wired similarly.

Chris

[racerrad8]

The red wire is to be hooked to the constant battery 12v positive. The brown wire should be a fused switched 12v wire. It will charge either way, but if hooked up backwards, the alternator will keep the engine running as the "excite" (brn) wire is the one hooked to constant 12v power.

I have attached a couple of the Legend car wiring diagrams;

http://www.haleyracingclub.com/images/Legends_color_wiring_diagram.jpg

http://charlesking.net/Legends-Car-Wiring-Diagram.html

That is all you need to run all of the engine supply systems.

Randy - RPM

[fj1289]

Thanks Randy!

I set my electrical system up slightly different - I run battery power through two solenoids (parralleled for redundancy) to the fuse block.  I use the main switch (a toggle) through the tether (safety) switch to control those relays.  If I switch off the main switch OR the tether gets pulled, ALL power distribution is killed.  I provide power for the ignition system (including the coils) from the fuse block through a relay that is controlled by the engine kill switch.  This way I can crank the engine without the ignition if needed - or get the high compression engine spinning first and then throw the spark at it. 

I have both the red and brown wire ganged together at the solenoid post where the battery connects - similar to the wiring diagrams enclosed. 

I'm going to have to study those diagrams a bit to see if I can simplify my wiring a bit.  Unfortunately I've ended up with 4 circuits - ignition & shift kill, lights, shifter & shift light, and data aquisition & O2 sensor.  Still some expansion room for later if needed. 

How's the recovery going?

Chris

[racerrad8]

Make sure you fuse the brown wire. If the alt shorts and there is no fuse...bye-bye to the delicate electronics...

Doing good. I have as of 7 days after surgery weened myself from the pain pills. So I am feeling more of the surgery site pain but the leg, other than being weak, seems to be all taken care of. I see the Dr on Tuesday and then maybe I can start doing a few thing including driving.

Randy - RPM

[fj1289]

Well, a partial update on this. 

No damage, but found it's not a good idea to wire the brown and red together.  The voltage reg (brown wire) maintains partial connectivity to ground (about 3.4 on the 200K ohm scale) when not running (I checked this against another alternator too and had the same resistance).  This puts a constant slight draw on the battery (had both battery and generator connected together at the start solenoid).  I've split the brown wire back out and it will go to the power input on the fuse block and won't drain the battery when the main switch is off.

With any luck, this is my electrical gremlin...