Cascade Crew

iansane · Posted: Sun Jul 29, 2007 4:55 pm Post subject: Alternator Issue...

Last night I drove to West Seattle because Dirty Steve's brother bought a bar out there. Pretty nice place, pool tables which I HAVE to have when I go to a bar, awesome live up tempo jazz music and good company. ANYWAYS, on the way up I got into a skirmish on I5 north with what sounded like a boosted s2000. I thought I heard a wastegate and at least a BOV and held my own pretty well. He was barely pulling. Less than Schultzy did at cows right before he lost the dizzy gear.

Bah, I keep getting sidetracked. On the way home I noticed my volt guage stuck to 8. It stayed like that until I hit gig harbor and my car started running like absolute ass until I got home. I trickle charged the battery all night and went to work this morning and it seemed to drive okay. I tested the alternator and it was fine. Went ahead and warrantied it anyways just to be safe. Load tested the battery and it came up bad instantly. Swapped it out for a new one and thought I fixed the problem. Nope. Still not charging voltage. Did some poking around with my DVOM and figured out the brown turn on wire for the alternator wasn't showing any voltage. By this time John and James (RSfreak and Turbojimi) showed up and BS'd with my buddy alex and I. I spliced into the brown wire and just fused it directly to the battery and success! It's now charging at 14v but I'd like to wire it correctly. Does anyone know where the brown wire gets its power from? And why when the car was turned competely off, the fan came on when I applied power to that wire. I ended up just running a fused wire directly from the battery to the alternator just to get the car home and drive around for awhile.

Help?

Al Hasse · Posted: Sun Jul 29, 2007 6:05 pm Post subject:

Here's the best I could find from TGO, I found other descriptions, but this image re-enforced all the write-ups I found. The brown wire connects to your ignition switch through the charge light (or gauge). Thought I had the same problem last winter, no charging and no power to accessories (fan, HVAC blower), turned out to be the ignition switch.

aaron_sK · Posted: Sun Jul 29, 2007 7:49 pm Post subject:

Hmm... seems to vary a lot by year. Haynes says brown wires is hooked into the 20A fan fuse in the panel.

Al Hasse · Posted: Sun Jul 29, 2007 7:54 pm Post subject:

That could explain why his fan comes on when he applied power to it with the car off. Confused

aaron_sK · Posted: Sun Jul 29, 2007 8:00 pm Post subject:

Al, you know more about this than I do: In reading on TGO it seems that in later years GM ditched the voltage regulators and resistance wires that they used in early models, and just ran the brown wire from the fan.

Was that supposed to be a cheap way of getting the voltage?

*Edit: Found this too...

http://www.thirdgen.org/techboard/posts/electronics/170850-cs-alternator-conversion-problems/1232946-post5.html

Al Hasse · Posted: Sun Jul 29, 2007 8:18 pm Post subject:

While trobleshooting my problem last winter (initially I thought it was in the alarm), the tech at Mobile Radio brought up All Data, which the store subscribes to, and found that the sense wire does indeed go to the ignition switch via the dash light (or gauge) with a resistor in parallel, which I don't know the value of.

My system is just a bit different since I have a diode type isolator so the alternator charges 2 batteries. Only real difference is the battery wire (cable) off the alternator goes to the isolator where it splits to go to each battery. With the car off, I have zero volts at the back of the alternator. The isolator has a 4th "excitation" wire hooked to an ignition source to allow current to flow from the alternator. My alternator harness is still stock with a red and a brown wire. The red wire in the harness I assume goes to the fuseable link at the starter and the brown one goes to ignition switch.

iansane · Posted: Sun Jul 29, 2007 8:43 pm Post subject:

So basically it should come from the ign hot side of the switch?

chevymad · Posted: Sun Jul 29, 2007 9:36 pm Post subject:

If you simply connect it to the ignition switch without a resistor, you won't be able to turn the car off. The resistor is there to keep the current from backflowing and feeding the ignition side of the switch. When I converted my old pickup to an internally regulated alternator, I had to wire in some diodes in that wire. Truck just wouldnt shut off lol.

Al Hasse · Posted: Sun Jul 29, 2007 9:49 pm Post subject:

Done some more diggin'. Should be connected to the same pin as the orange IGN wire out of the switch. Should also be a resistor in line with the brown field wire (about 10 ohms). On some of the diagrams I found, there was a resistance wire used for part of the field wire. On the bottom part of this diagram...which came from here...
http://www.geocities.com/vtcamaro/Wire-Diagrams.html
These are for 1985 Camaro, but should be similar.

Edit: Looking over this diagram and considering that your fan turned on when you applied power to the field wire makes me think that 12V is not present at the ACC orange wire. Check to see if you have power to your fan when the car is running, If you don't, then you may have a bad switch.

iansane · Posted: Mon Jul 30, 2007 6:44 am Post subject:

Holy crap! Thanks Al! I'll be checking today before I go to work!

blue89 · Posted: Mon Jul 30, 2007 7:07 am Post subject:

I just had to wire up a 3 wire alt in my boat. What a pain that was. I ended up using a diode to make sure current flows into pins 1-2 and not out. I don't have a true ignition wire for my engine and it kept backfeeding into the coil, keeping the boat alive! So I eventually found that the diode did the trick. I guess a resistor would work too.

iansane · Posted: Mon Jul 30, 2007 7:56 am Post subject:

So that also powered my guages? Which would have explained why I popped two guage fuses yesterday. Looks like I need a switch. Can the resister go bad?

Al Hasse · Posted: Mon Jul 30, 2007 11:28 am Post subject:

It's not really a resistor, but a resistance wire. If it went bad and opened, then you wouldn't have been able to turn on your fan when you applied power to the wire. If it shorted (which it almost is anyhow at 10 ohms), you would still have seen voltage there with the car running.

The resistance is there to provide a voltage difference to the alternator field so the alternator will turn on.

This seems identical to my bad ignition switch last winter, I had no fan, no HVAC blower, no charging. As soon as I replaced the ignition switch, the lock cylinder went bad and we couldn't turn the key off Shocked

. The ignition switch was very easy by comparison to the lock cylinder - lowering the column is much easier than pulling the wheel.

iansane · Posted: Tue Jul 31, 2007 10:18 pm Post subject:

Well that was a pain in the ass.... I swapped a new ignition switch in (and also adjusted my high beam switch a little) and that wire still has less than a tenth of a volt with the key on. I guess I'll just have to trace wires.

Al Hasse · Posted: Thu Aug 02, 2007 11:39 am Post subject:

Sorry you went through all that trouble. From the indications you described, it seemd likely to be the ignition switch.

iansane · Posted: Thu Aug 02, 2007 3:12 pm Post subject:

Figured out what it was. The wire that went into the FAN fuse was crack and broken. So it was getting power, just not enough. Pulled out the spade terminal in the fuse block, slapped on a new one and I'm good to go!

Gotta love chasing down wires.