8 Volts At The Hood Latch?

[Draenor]

[Spurshot]

Ya think?

[gjr]

sorry the original got cut off. I own a 99 gmc suburban 1/2 ton 5.7l. For some reason when the key is on there is 8volts anywhere your touch a mulit-meter. And nothing has any power. So far the battery, alternator, starter and grounds including the positive wire has been tested. The only thing i can think is maybe the ignition switch? I am at a loss with this one. It dosent matter if the key is in the run postion or the acc. position. Also the negative cable gets very warm with the key on but not when off. The only other problem i have had is an intermitent one with the turn signal, cruise, washer tree on the column not completely shutting power off to the blinker switch. IE>.. the flasher keeps clicking but the lights do not light and if you wiggle it a little it stops. The 8 volt thing is anywhere the alternator case the hood latch the grounds, but only when the key is on not when its off.

 

 

Any ideas? I've owned this thing since new and it now has 160K on it and i have never had a problem before.

 

I had to post a new topic because in all the other dead vehicle posts nobody mentioned a voltage anywhere.

 

 

Any and all help is appreciated.

[Spurshot]

It could be a short anywhere power and ground come together, either internal to a harness or to a structure. Big easter egg hunt. You can diagnose by starting from all fuses in place and start pulling them one at a time until the power in the structure goes away. That will give you the circuit to follow and check every inch of the way. Not a brief task, but will get you to the problem circuit quickly.

[Spurshot]

I'm not sure on your Classic body 99, but my 99 NBS (GMT800) 2500 has a fuse panel under the hood and another on the driver side of the dash (seen with the door open).

[gjr]

It could be a short anywhere power and ground come together, either internal to a harness or to a structure. Big easter egg hunt. You can diagnose by starting from all fuses in place and start pulling them one at a time until the power in the structure goes away. That will give you the circuit to follow and check every inch of the way. Not a brief task, but will get you to the problem circuit quickly.

 

 

Did that. It came back to the ignition fuses under the hood the 40 and 50 amp. Should've added that. Thats what got me to the ignition switch. 170 bucks is a lot to throw at a guess though, even a little bit of an educated one.

[music]

8V between hood and "what ground point"?

[gjr]

8V between hood and "what ground point"?

 

 

The battery. With the multi grounded at the battery there is 8 volts on everything metal. I first noticed while i was checking for power at the atlernator i dragged the positive lead across the case and it flashed so i tested it and sure enough power everywhere there shouldn't be.

[jpk]

Check for a short in the alternator. First, try disconnecting the alternator wire to the battery. If you still get your 8volts, the problem is elsewhere.

[music]

Just a note. It's not possible for the hood to be grounded to the chassis *and* still get 8V between it and the battery ground post, unless the battery itself isn't grounded to the chassis. The only way to measure a voltage drop is to have resistance between the two points.

[gjr]

Just an update. Replaced some ground wires and still nothing. Added a ground from the alternator to the top post of the battery and she fired right up. However after running for about 15 minutes the alternator is so hot water sizzles on it and its charging 143 amps. Stumped again. Re-tested the alternator and its still good. The factory guage in the truck says about 13 volts but at the battery its charging 14.5 volts. Thinking about adding some more ground wires........

[music]

Just an update. Replaced some ground wires and still nothing. Added a ground from the alternator to the top post of the battery and she fired right up. However after running for about 15 minutes the alternator is so hot water sizzles on it and its charging 143 amps. Stumped again. Re-tested the alternator and its still good. The factory guage in the truck says about 13 volts but at the battery its charging 14.5 volts. Thinking about adding some more ground wires........

 

In case... have you checked the battery? The battery is part of the alternator circuit, so if it's shorting internally "to ground" across a cell, then that would explain a lot. I've never seen it happen, but I'd check it. The unconnected battery should read 12+ volts across the terminals. I wouldn't rule out the alternator either... bench tests aren't perfect.

[Spurshot]

Rather than trying to troubleshoot the battery itself, change it with another if you have one in another vehicle.

 

That alternator sounds like a suspicious "component of interest". Other suspects could include the starter solinoid (starter assy)

[music]

Another simple thought. Make sure the battery is fully "bonded" to the chassis (i.e., no corrosion, tight, etc.).

[gjr]

Actually MusicMan it was your post about the hood ground that got me working on the ground wires again. I tried another batttery and have the same result. In the morning I'm going to swap the alternator and hope for the best. Also I added another ground, motor to chassis and battery to chassis. So back to the alternator. After 160K maybe its time to replace it anyways. More updates tomarrow.

 

 

Thanks again for your info guys.