voltage and electrical issue on my 88

[benoit454]

ok here's what's going on...

88 chevy k1500 rebuilt 350 tbi brand new battery, and now has another known good one, tested the alt. at autozone twice, passed. When we try our snapon charging system tester at the battery it reads just over 12 volts running, same as it does not running. While on dad's 84 c10 with either battery mentioned his runs 14.5 or so volts while running.

So, what I gather so ar the batteries are good either one of them, the charging system tester is working, my alt. passed the test twice, so somehow somewhere something in my systyem is messed up.

My alt. works but is not getting power back to the battery? if so how and why?

Maybe loose wire causes this? bad ground or unhooked ground?

sensor?

The thing ran fine, no issues that I know of, just had a knocking noise, turned out to be the starter spring in the bendix or whatever it's called, it was wound behind the plate it rides on and holding the gear out hitting the flexplate. I took the trans and t-case out thinking it was a bad flexplate, put it all back together and now this.

Maybe a fuse is causing this? anyone have any ideas? I have to check it out sometime but I don't get much time now.

When I first put in the new battery and started it, the gauge was bottomed out lower then 8, then it came up to around 10 or so whatever is the middle of 8 and 12 or 14, it stayed there, then when we tried to drive it went to nothing and stayed there. This was a couple days in between but nothing changed that I know of.

[scotts62]

The wire from the back of the alt goes to the battery, i would check that first.

Check it with a volt meter running and have someone raise the RPM's up and see if the voltage raises too if not the alternator could be working but not enough of a charge. Sounds like alt to me.

[benoit454]

I think it's the alt. too but they tested it and it passed.

I checked mine and it runs to the junction block on the firewall, ran a new wire and nothing, ran a new one with the old one and nothing.

I checked all fusible links, good, all fuses, all good, grounds connections, plugins all good.

I got an ammeter in the gauges mounted under my dash thinking of trying it out but it says it hooks to the starter solenoid and confuses me on how or where to hook it up. One I get post A as it calls it on the solenoid and goes to battery so I'd guess the big post, the other neg for the gauges says to the wires that came off post A. I have no wires on post A or the big post other then the battery and only one small solenoid wire.

[Dark Knight]

I just saw something about this on Powerblock TV this weekend. They said take a wire and run it from the back of the alternator to the intake manifold. Any one of the four screws that hold the alternator body together will work. This will ensure a good ground. I would also clean the cable really well at the battery and the ground on the block.

[scotts62]

Originally Posted by benoit454

I think it's the alt. too but they tested it and it passed.

I checked mine and it runs to the junction block on the firewall, ran a new wire and nothing, ran a new one with the old one and nothing.

I checked all fusible links, good, all fuses, all good, grounds connections, plugins all good.

I got an ammeter in the gauges mounted under my dash thinking of trying it out but it says it hooks to the starter solenoid and confuses me on how or where to hook it up. One I get post A as it calls it on the solenoid and goes to battery so I'd guess the big post, the other neg for the gauges says to the wires that came off post A. I have no wires on post A or the big post other then the battery and only one small solenoid wire.

Has happened to me more than once when tested at a local parts store. They definitely should know more before they are hired there

[benoit454]

lol when I get paid I'm thinking of buying a new one and try it.

I just hope if that doesn't fix it I can return it.

I may try the ground wire deal though, and I may also try the old yank the battery terminal off while running and try it.

[gmtec93c1500]

perform these 2 test and report to me with the answers

[gmtec93c1500]

sorry bout the small pic...


test 1

connect a heavy gauge wire between 1 and 2

with the engine running check batt voltage

test 2

use a test light and connect it between 1 and 3

with the engine running dose the test light "light"?

with the engine running check the batt voltage

[speedygonzales]

Sounds to me like the "L" terminal on your alternator is not getting voltage when it's put on your truck.

[benoit454]

I did test one yesterday nothing changed.

I tried test 2 and hooked the aligator clip to my battery hot terminal then tried to stab that wire to the gauge, no light lit up or anything but after doing so I guess(never looked at the meter once I hooked it up) it was putting out 14 or so volts.

Then I had a CEL and had codes 33,34, and 45 and checked, sure enough MAp sensor was almost unhooked(clip is broke) rehooked it, cleared the computer, ran smoother and had over 14 volts running.

Now I need to test drive and maybe change plugs they are all black now.

[gmtec93c1500]

i would say check the connection on on the L terminal the pin is prob not makin a good connection ....