Home » Public Forums » GMCnet » Pain in the Alternator!!! (or, the alternator chronicles.)
| Pain in the Alternator!!! [message #93631] |
Wed, 28 July 2010 10:33  |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
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Ok, heres the story. When I decided to go with the 2115 Edle. intake manifold I knew I needed a new mount for the AC comp. I figured if I were to make a new mount i midas well make it muti rib sepentine. So, I looked on the Cadilac Power forum, catalogs and other sources for pullys and ideas. I also did't know how old my preasent alt. was, age/milage. I measured the two diffrent types(heavy and lite duty here at the GMC plant) 140 amp each with the same mount dimensions, ones a little smaller. The Lite duty had a two wire hookup, the heavy 4. Looking at the schematics (all online, as are the service manuals) I saw it loked like all other alt. hookups. Couldn't find any vans at the mens mall but it looked like Pu's were the same. Got a HD off a 2500HD rollover, MY2007.Made all the brackets for the belt conversion. PS pump low and to the left. Alt. high and right.(Batteries are on the right.)AC comp. low and to the right below the alt. Ran on breakin. Probably a total of 2 hours due to a bad cam(another story). Remember I had the front clip out and rolled inside my shop.
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| Re: Pain in the Alternator!!! [message #93641 is a reply to message #93631] |
Wed, 28 July 2010 11:10  |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
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When I installed the clip the alt. was to high. Was going to hit the floor. Loosened the belt brought it down. Later I had to take it all apart and lower it, real pain now it was all under the floor. Whaen I got it fired up I was so busy with leaks, cheap valve covers, PS that I couldn"t check for voltage. When I did check, NO VOLTAGE, #$*&#&$#???? Checked and double checked the wiring. No joy. So I looked at the service manual for trucks online at work,,,,,,,,O NO,the alternators are computer controled by the ecm. The S.Manuale stated the alt. put out voltage in response to a 5V. pulse width modualted signal from the ecm. Bummer. Showed a nice chart with the alt. at a diffrent % duty cycle for each signal and the voltage it made. No way I was going to duplicte that signal. Called the enginiers in detroit that design it, the said "good luck". Went and got another alt. ata diffrent yard, specified 2001 or older PU truck. The service manual stated that was the last year for non-comp. control. STILL no voltage. Took that one apart and de-solderd the regulator and looked online for V.reglators that would fit and were non-ecm controled. Nothing looked to fit. Took both to A.zone. Both good. Found a rebuilder 20 miles south of home. Told him the whole story(no laughter). he asked me what was wrong with the old one? Wrong pully and it was old I said. He solderd in the regulator, ran it on the tester and,,,,VOLTAGE,,,14.6. He told me how to hook it up, checked my notes and it was the same. Only 3 wires and you can't screw up the big one. Went home and tried it again,,,,,nada-zilch. 0-volts. WHAT THE,,,,,. Went back after work the next day, stood next to him and he cranked on a big knob labled "PILE", the voltage dipped to 11.9 and ramped up to 14.2 with the amp meter at 142!!! holey cow,,,it does work. Saw it with my own eyes. The rebuilder ask how I hooked it up again. Same as right there. Asked me again what it was on,,, 78 GMC MOTORHOME!!!!! Motorhome he asked?? Ya MH. Do you have an isolator???? Yes sir. He says " thats the problem" sold me an 8 doller diode soldered to some wires. Package labled Mechanics diode. Wanted to know if I knew how to hook it up.(electrician for 32 years but you cant tell by how I can get an alt. to work) He stated it needed 12v. at the BIG POST to tickel it. Works great. Now I have a spare alt. can't explain why the service manual states it's computer controled??????? Go figure. sorry so long. ,,,guess that shows that ya think you know how a simple alt. works,,,only 3 wires???PL
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| Re: [GMCnet] Pain in the Alternator!!! [message #93665 is a reply to message #93641] |
Wed, 28 July 2010 12:22 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Paul,
I'm not sure whether my CS130D requires battery voltage to begin charging or
not, but I imagine it does. So the reason I didn't go through the same sort
of agony you did is that I have a combiner -- the alternator output's always
connected to the chassis battery so no "mechanic's diode" needed.
Score one more for combiners. :-)
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Wed, Jul 28, 2010 at 12:10 PM, Paul Leavitt <leavittpaul@yahoo.com>wrote:
>
> ......Works great. Now I have a spare alt. can't explain why the service
> manual states it's computer controled??????? Go figure. sorry so long.
> ,,,guess that shows that ya think you know how a simple alt. works,,,only 3
> wires???PL
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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