voltage and charging

kuby67 · Post by **kuby67** » February 3, 2008, 9:36 pm

After a week of chasing ghosts, my 65 f100 slick ended up having a bad ignition switch center post. A new ignition switch was installed and a new problem came to call...

The electrical system is now maxing out at 12.7 volts (alt light stays on). The alternator and voltage regulator were tested and are OK/ all known grounds have been cleaned and grounding straps replaced. (The problem seems to be somewhere between my cerebral cortex and spinal cord.) Before this new voltage problem, I had been connecting a battery-hot, yellow wire to the old ignition switch center post to power the instruments, etc; there was no ALT light and the charging system was 14+ volts. Logic suggests that I once again connect this HOT yellow wire to the hot center post but logic suggests that might not be a good idea. Help

blackagatha · Post by **blackagatha** » February 5, 2008, 10:53 pm

check the terminal on the end of your hot wire... sounds like the wires may have broken where it is crimped, may be making a buttload of resistance.

Rosati · Post by **Rosati** » February 5, 2008, 11:54 pm

link-a-doo!

Follow this link to have a look at the regulator hookups.
I suspect your ignition switch wire is not hooked up The "I" terminal on the regulator)
Try running a jumper from the battery to the "I" terminal and see if you start charging. If so, you need to trace the "I" wire back to the switch.
If you try the jumper wire, you may not be able to shut of the truck with the key until you unhook the "I" terminal (bypasses the IGN switch)

kuby67 · Post by **kuby67** » February 6, 2008, 1:57 pm

I tried that and it made no difference in the system voltage. Is the voltage at the I terminal voltage regulator supposed to drop to 6 volts when the vehicle is running? (harness connected to regulator)

kuby67 · Post by **kuby67** » February 13, 2008, 1:53 pm

not sure if anyone is still watching but the problem ended up being in the field wire. It had a partial break in it. I had previously tested the continuity and it was fine. I tested it again and it was no good. Field wire replaced, problem solved. Thanks for the info!!

Slick Fan · Post by **Slick Fan** » February 13, 2008, 3:06 pm

I missed this thread the first pass, but I'm glad you found your problem.

Wiring problems can be a bugger.

Rosati · Post by **Rosati** » February 13, 2008, 9:22 pm

Kuddos on finding the fix.

ICEMAN6166 · Post by **ICEMAN6166** » February 13, 2008, 11:37 pm

glad you were able to kill the gremlin.
i have run across that issue before, wire has a bad spot, depending on how you move it , may or may not get power thru.

GLindley · Post by **GLindley** » February 16, 2008, 8:23 pm

Is the "battery post" on an externally regulated alternator be "hot"with engine off and key off?
My Gen light came on the other day, and I took off my alternator and had it checked. The alt was bad, but when I put the new one on, still have the Gen light on with engine running. Took alt back and had parts house check it. Checked out okay. While putting the alt back on the truck with a ratchet, I touched the engine and bat post on the alt and it sparked.

kuby67 · Post by **kuby67** » February 16, 2008, 10:50 pm

ouch!!! I don't know too much about electrical. But if the ALT is not supposed to have voltage when the key's off it could be a bad solenoid.

ICEMAN6166 · Post by **ICEMAN6166** » February 17, 2008, 10:58 am

GLindley wrote:Is the "battery post" on an externally regulated alternator be "hot"with engine off and key off?
My Gen light came on the other day, and I took off my alternator and had it checked. The alt was bad, but when I put the new one on, still have the Gen light on with engine running. Took alt back and had parts house check it. Checked out okay. While putting the alt back on the truck with a ratchet, I touched the engine and bat post on the alt and it sparked.

Gene, the bat post on any alt or gen is always hot, as it is a direct wire from the bat.

when i dig up that speedometer cable, i will find you an "alt" insert for your instrument panel to replace the "gen" one if you want.

GLindley · Post by **GLindley** » February 17, 2008, 11:58 am

Thanks Ice, that would be nice! (Did THAT just rhyme?). As you can see, though, I have wiring gremlins to run down. And what little I know mechanically, I know even less electrically...(sigh)...