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Alternator remote sense [message #346009]

Sat, 03 August 2019 11:05

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

I have to replace my alternator. The one just removed is a confirmed kill due to mechanical damage. The replacement that I picked up years ago is another 27SI, but I have no confidence that it is remote sensing.

Is there any kind of an external electrical check that I can do to confirm or deny that it is a remote sensing regulator??

Yes, I have gone a serious on-line search, but all Delco will tell me is that their remote sensing machines have an external terminal.

Thanks

Matt

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

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Re: Alternator remote sense [message #346020 is a reply to message #346009]

Sat, 03 August 2019 23:17

Rick Staples

Messages: 126
Registered: May 2014
Location: Johnstown, Colorado, USA

Karma: -1

Senior Member

I believe the remote sensing 27SI alternator the GMC uses can be identified by the two small male disconnect terminals on the voltage regulator. These protrude (slightly) through the case at about the 10 o'clock position when viewed from behind. The one you want will have a small terminal marked "B" or "Bat", alongside the one connected to the warning light. This allows the alternator to sense the voltage of the battery directly, bypassing the diode isolator. The type you DON'T want is the so-called "one wire" or "machine sensed" alternator, which only has one small terminal for the idiot light (if that), and one big stud and nut connecting to the battery, via the isolator in our case.
HTH
Rick Staples

Rick Staples, '75 Eleganza, Johnstown, CO "Advice is a dangerous gift, even from the Wise to the Wise, and all paths may run ill." -Tolkien

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Re: Alternator remote sense [message #346025 is a reply to message #346020]

Sun, 04 August 2019 07:01

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

Rick Staples wrote on Sun, 04 August 2019 00:17

I believe the remote sensing 27SI alternator the GMC uses can be identified by the two small male disconnect terminals on the voltage regulator. These protrude (slightly) through the case at about the 10 o'clock position when viewed from behind. The one you want will have a small terminal marked "B" or "Bat", alongside the one connected to the warning light. This allows the alternator to sense the voltage of the battery directly, bypassing the diode isolator. The type you DON'T want is the so-called "one wire" or "machine sensed" alternator, which only has one small terminal for the idiot light (if that), and one big stud and nut connecting to the battery, via the isolator in our case.
HTH
Rick Staples

Rick,

Thank you, but the problem is that all the Delco XXSI regulators have the two terminals. When this alternator was repaired once (because the regulator failed), the installed regulator was not remote sense. I figured out in short order what a difference is makes. I am hoping to confirm that the spare I have does have the remote sense regulator without having to crack the machine open.

Matt

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Re: [GMCnet] Alternator remote sense [message #346026 is a reply to message #346025]

Sun, 04 August 2019 08:01

GMC.LES

Messages: 505
Registered: April 2014

Karma: -2

Senior Member

Out of curiousity, does anyone have a part number for the “correct” voltage regulator?

Les Burt
Montreal
'75 Eleganza 26'

> On Aug 4, 2019, at 8:02 AM, Matt Colie via Gmclist wrote:
>
> Rick Staples wrote on Sun, 04 August 2019 00:17
>> I believe the remote sensing 27SI alternator the GMC uses can be identified by the two small male disconnect terminals on the voltage regulator.
>> These protrude (slightly) through the case at about the 10 o'clock position when viewed from behind. The one you want will have a small terminal
>> marked "B" or "Bat", alongside the one connected to the warning light. This allows the alternator to sense the voltage of the battery directly,
>> bypassing the diode isolator. The type you DON'T want is the so-called "one wire" or "machine sensed" alternator, which only has one small terminal
>> for the idiot light (if that), and one big stud and nut connecting to the battery, via the isolator in our case.
>> HTH
>> Rick Staples
>
> Rick,
>
> Thank you, but the problem is that all the Delco XXSI regulators have the two terminals. When this alternator was repaired once (because the
> regulator failed), the installed regulator was not remote sense. I figured out in short order what a difference is makes. I am hoping to confirm
> that the spare I have does have the remote sense regulator without having to crack the machine open.
>
> Matt
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

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Re: Alternator remote sense [message #346027 is a reply to message #346009]

Sun, 04 August 2019 09:01

JohnL455

Messages: 4447
Registered: October 2006
Location: Woodstock, IL

Karma: 12

Senior Member

Isn't it like 60 seconds to zip out 4 screws and separate the case to see if jumped internally? Which brings us to the next question of is there a correct way to disassemble without cracking the the brush holder when brushes catch on rings? I understand reassembly using a spray straw brush keeper. Did a cs144 a week ago.

John Lebetski
Woodstock, IL
77 Eleganza II

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Re: [GMCnet] Alternator remote sense [message #346029 is a reply to message #346027]

Sun, 04 August 2019 09:11

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

They taught us to use toothpicks to retain the slip ring brushes in GM
school. That is why there is a small hole drilled through the brush holder.
The hole also serves as a quick check to check for brush wear.
Jim Hupy
Salem, Or

On Sun, Aug 4, 2019, 7:02 AM John R. Lebetski via Gmclist <
gmclist@list.gmcnet.org> wrote:

> Isn't it like 60 seconds to zip out 4 screws and separate the case to see
> if jumped internally? Which brings us to the next question of is there a
> correct way to disassemble without cracking the the brush holder when
> brushes catch on rings? I understand reassembly using a spray straw brush
> keeper. Did a cs144 a week ago.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Re: [GMCnet] Alternator remote sense [message #346031 is a reply to message #346025]

Sun, 04 August 2019 09:58

Ken Henderson

Messages: 8726
Registered: March 2004
Location: Americus, GA

Karma: 9

Senior Member

Big Shame-faced confession: Some years back, after installing a combiner,
I jumpered the remote sense line to the output terminal of my 27 SI. I ran
that way for several years before installing the Cad500 (with a CS130
alternator). I never had a problem with battery condition -- but I DID pay
a lot of attention to all of my wiring, including the primary lead from the
alternator and the battery terminals.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com

On Sun, Aug 4, 2019 at 8:22 AM Matt Colie via Gmclist <
gmclist@list.gmcnet.org> wrote:

> Rick Staples wrote on Sun, 04 August 2019 00:17
>> I believe the remote sensing 27SI alternator the GMC uses can be
> identified by the two small male disconnect terminals on the voltage
> regulator.
>> These protrude (slightly) through the case at about the 10 o'clock
> position when viewed from behind. The one you want will have a small
> terminal
>> marked "B" or "Bat", alongside the one connected to the warning light.
> This allows the alternator to sense the voltage of the battery directly,
>> bypassing the diode isolator. The type you DON'T want is the so-called
> "one wire" or "machine sensed" alternator, which only has one small terminal
>> for the idiot light (if that), and one big stud and nut connecting to
> the battery, via the isolator in our case.
>> HTH
>> Rick Staples
>
> Rick,
>
> Thank you, but the problem is that all the Delco XXSI regulators have the
> two terminals. When this alternator was repaired once (because the
> regulator failed), the installed regulator was not remote sense. I
> figured out in short order what a difference is makes. I am hoping to
> confirm
> that the spare I have does have the remote sense regulator without having
> to crack the machine open.
>
> Matt
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
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Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach

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Re: Alternator remote sense [message #346059 is a reply to message #346009]

Sun, 04 August 2019 18:50

JohnL455

Messages: 4447
Registered: October 2006
Location: Woodstock, IL

Karma: 12

Senior Member

James,yes I understand the brush holder holes and the one in the rear case. They give you a metal wire keeper with nee brushes, but I like the spray can straws. The question is for disassembly. You can't insert a toothpick or anything else while brushes are spring loaded against slip rings.

John Lebetski
Woodstock, IL
77 Eleganza II

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