10si alternator - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Awann99 · 08-15-2023, 08:08 PM

I'm having some electrical issues with my truck 72 k2500 350 4 speed.
Left my lights on a few days ago . Battery was dead the next morning. Swapped a new battery. Alternator was reading in the low 14s. Got to work and the truck was dead when I got out. Got a jump and to the parts store. All they had in stock closest to my year was a 1980 Camaro alternator. 10si internally regulated. Swapped the wiring over and headed out. Charging at 13.5 and slowly climbing. Battery was at 11.23 this morning. Any ideas and how to track this down. It's slowly draining when off.

My alternator wiring harness also did not have a ground wire.

To change the wiring I ran the blue wiring to the number one spot on the alternator. Rant the number 2 spot to the battery stud. Tan the red wire to the battery stud. The white wire on the original harness is snipped and I ran a jumper from the brown to blue write on the old regulator plug. Did I miss something?

MARKDTN · 08-17-2023, 09:08 AM

I'm a bit lost in the description but: Main lug goes to main lug. #2 on alternator should have 12V all the time. Some just jump it to the main lug. #1 on alternator goes to the light on the dash.

But I'm confused why you changed the alternator to internal regulator if you just left your lights on? Seems like something else is going on?

Awann99 · 08-17-2023, 07:54 PM

Quote:

Originally Posted by MARKDTN

I'm a bit lost in the description but: Main lug goes to main lug. #2 on alternator should have 12V all the time. Some just jump it to the main lug. #1 on alternator goes to the light on the dash.

But I'm confused why you changed the alternator to internal regulator if you just left your lights on? Seems like something else is going on?

I left my lights on and it killed the battery. The next day my battery was dead so I had the alternator tested. It failed. The parts store only had a 10si in stock so I installed that. Now it drains my battery over night. Not sure why. With the 1&2 plugs hooked on it drain .01 bolts every second. I unplugged the 1&2 and the drain stops. Could I install a diode in the key on wire to stop the draw?

zosoppp · 08-18-2023, 07:08 PM

Here's a link to one of the many many threads on the conversion to internally regulated alternators (10si or 12si).

http://67-72chevytrucks.com/vboard/s...d.php?t=362957

**MikeB** · 08-18-2023, 10:34 PM

Deleted

Awann99 · 08-26-2023, 12:01 PM

Quote:

Originally Posted by zosoppp

Here's a link to one of the many many threads on the conversion to internally regulated alternators (10si or 12si).

http://67-72chevytrucks.com/vboard/s...d.php?t=362957

Thank you. I'll take a look at this.

08-18-2023, 07:08 PM	#4
zosoppp Registered User Join Date: Mar 2014 Location: Lincoln Park, NJ Posts: 189	Re: 10si alternator Here's a link to one of the many many threads on the conversion to internally regulated alternators (10si or 12si). http://67-72chevytrucks.com/vboard/s...d.php?t=362957 __________________ 1970 C10 LWB 350SBC, SM330 Muncie (not saginaw SM326) (on tree), 3.07 open (assumed), PS, PB, Idiot lights

08-18-2023, 10:34 PM	#5
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,462	Re: 10si alternator Deleted __________________ Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

08-15-2023, 08:08 PM	#1
Awann99 Registered User Join Date: Jan 2018 Location: TN Posts: 257	10si alternator I'm having some electrical issues with my truck 72 k2500 350 4 speed. Left my lights on a few days ago . Battery was dead the next morning. Swapped a new battery. Alternator was reading in the low 14s. Got to work and the truck was dead when I got out. Got a jump and to the parts store. All they had in stock closest to my year was a 1980 Camaro alternator. 10si internally regulated. Swapped the wiring over and headed out. Charging at 13.5 and slowly climbing. Battery was at 11.23 this morning. Any ideas and how to track this down. It's slowly draining when off. My alternator wiring harness also did not have a ground wire. To change the wiring I ran the blue wiring to the number one spot on the alternator. Rant the number 2 spot to the battery stud. Tan the red wire to the battery stud. The white wire on the original harness is snipped and I ran a jumper from the brown to blue write on the old regulator plug. Did I miss something?

08-17-2023, 09:08 AM	#2
MARKDTN Registered User Join Date: Jan 2011 Location: Chattanooga, TN Posts: 2,142	Re: 10si alternator I'm a bit lost in the description but: Main lug goes to main lug. #2 on alternator should have 12V all the time. Some just jump it to the main lug. #1 on alternator goes to the light on the dash. But I'm confused why you changed the alternator to internal regulator if you just left your lights on? Seems like something else is going on? __________________ '83 K20-TPI '73 C10 '79 C10-ex-diesel(SOLD) '07 Tahoe(Son driving) '14 Suburban-DD '71 C10-current project



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