GMCforum: GMCnet » help to ID a part and its purpose

Home » Public Forums » GMCnet » help to ID a part and its purpose

Show: Today's Messages :: Polls :: Message Navigator

help to ID a part and its purpose [message #139152]

Sun, 14 August 2011 19:25

chasingsummer

Messages: 434
Registered: May 2011
Location: asheboro, nc

Karma: 0

Senior Member

i have 2, one in rear above battery, and one up front below "positive" jump point on firewall. it is a little bigger around than a golf ball and maybe 3 inches tall, the front one appears to have wires on it from both batteries, and one or 2 more smaller red wires
thanks bgk

brian asheboro, nc 75 eleganza, 74 build 119k miles and counting, DOG HOUSE

Report message to a moderator

Re: help to ID a part and its purpose [message #139155 is a reply to message #139152]

Sun, 14 August 2011 19:34

mike miller

Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon

Karma: 0

Senior Member

chasingsummer wrote on Sun, 14 August 2011 17:25

A picture would be nice.... you would get more accurate results. (we have a photo site for the pictures.)

That said, sounds like the boost solenoids.

Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo' http://m000035.blogspot.com

Report message to a moderator

Re: help to ID a part and its purpose [message #139167 is a reply to message #139152]

Sun, 14 August 2011 20:02

chasingsummer

Messages: 434
Registered: May 2011
Location: asheboro, nc

Karma: 0

Senior Member

i need to work on my pics, phone takes great ones, but size of them is in megs , more stuff to learn
i believe you are correct on the boost solenoid, i did a search for it and found a pic.
so amperage does not have to go thru boost switch. similiar to odding a solenoid to and old porsche since ignition switch over time could not carry loard to starter.

thanks brian

brian asheboro, nc 75 eleganza, 74 build 119k miles and counting, DOG HOUSE

Report message to a moderator

Re: [GMCnet] help to ID a part and its purpose [message #139171 is a reply to message #139152]

Sun, 14 August 2011 20:09

emerystora

Messages: 4442
Registered: January 2004

Karma: 13

Senior Member

On Aug 14, 2011, at 6:25 PM, brian wrote:

>
>
> i have 2, one in rear above battery, and one up front below "positive" jump point on firewall. it is a little bigger around than a golf ball and maybe 3 inches tall, the front one appears to have wires on it from both batteries, and one or 2 more smaller red wires
> thanks bgk
> --
> brian
> asheboro, nc

Brian

That is the solenoid that we talked about in previous emails. When you push the boost switch on the dash it gives power to one of the red wires on the solenoid (the other wire is a ground wire - you can easily trace it). When power is applied to the solenoid it closes the contact between the two large battery wires and joins (or jumps) the rear battery to the front battery. This is normally used when one battery or the other is dead so that you can start your engine or your Onan.

The rear solenoid is there only to jump across the rear circuit breaker so that you can get enough amps from your rear battery to start your engine. Without that the starter would draw more than 50 amps and trip the circuit breaker.

Emery Stora
77 Kingsley
Santa Fe, NM

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Report message to a moderator

Re: help to ID a part and its purpose [message #139174 is a reply to message #139152]

Sun, 14 August 2011 20:20

GeorgeRud

Messages: 1380
Registered: February 2007
Location: Chicago, IL

Karma: 0

Senior Member

They're both solenoids (front and rear), and allow a large amperage to flow through instead of overloading the boost switch.

JimB at the GMC Coop advises against just replacing them with a simple starter solenoid, as they are not rated for continual use. However, I can't think of many situations that you would keep them energized (except in an emergency when you are using the house battery to run the engine electrics) for more than a few seconds to start the engine with a dead front battery.

I believe that the rear one is only used to bypass a 50 amp circuit breaker in the rear circuit.

George Rudawsky
Chicago, IL
75 Palm Beach

Report message to a moderator

Re: [GMCnet] help to ID a part and its purpose [message #139177 is a reply to message #139174]

Sun, 14 August 2011 20:27

emerystora

Messages: 4442
Registered: January 2004

Karma: 13

Senior Member

On Aug 14, 2011, at 7:20 PM, George Rudawsky wrote:

>
>
> They're both solenoids (front and rear), and allow a large amperage to flow through instead of overloading the boost switch.
>
> JimB at the GMC Coop advises against just replacing them with a simple starter solenoid, as they are not rated for continual use. However, I can't think of many situations that you would keep them energized (except in an emergency when you are using the house battery to run the engine electrics) for more than a few seconds to start the engine with a dead front battery.
>
> I believe that the rear one is only used to bypass a 50 amp circuit breaker in the rear circuit.
> --
> George Rudawsky
> Chicago, IL
> 75 Palm Beach
>

George
You are correct on all that except for the fact that the solenoids that were original to the GMC were all rated continuous use. If you have one that is not continuous use than it has been replaced by a prior owner. I would not install an non-continuous use one as one never knows when you might want to manually jump it and leave it on for quite a while when charging both batteries from your 120 v. charger.

Emery Stora
77 Kingsley
Santa Fe, NM

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Report message to a moderator

Re: help to ID a part and its purpose [message #139196 is a reply to message #139152]

Sun, 14 August 2011 21:56

bukzin

Messages: 840
Registered: April 2004
Location: North California

Karma: 0

Senior Member

Have someone press the boost switch on the dash board
while you touch the various units.

Easy to see what is activated by the sound and vibration.

Bukzin
1977 Palm Beach

Report message to a moderator

Re: [GMCnet] help to ID a part and its purpose [message #139219 is a reply to message #139174]

Mon, 15 August 2011 03:36

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

G'day,

Jim also recommends installing a switch across the boost solenoid. If you
loose your batteries completely you can switch it on, start the Onan and it
will provide 12vdc to the engine.

http://www.gmcmhphotos.com/photos/showphoto.php?photo=39553

It's the one on the left marked Boost. ;-)

Regards,
Rob M.

-----Original Message-----
From: George Rudawsky

They're both solenoids (front and rear), and allow a large amperage to flow
through instead of overloading the boost switch.

JimB at the GMC Coop advises against just replacing them with a simple
starter solenoid, as they are not rated for continual use. However, I can't
think of many situations that you would keep them energized (except in an
emergency when you are using the house battery to run the engine electrics)
for more than a few seconds to start the engine with a dead front battery.

I believe that the rear one is only used to bypass a 50 amp circuit breaker
in the rear circuit.
--
George

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

Report message to a moderator

Re: [GMCnet] help to ID a part and its purpose [message #139243 is a reply to message #139219]

Mon, 15 August 2011 08:27

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Sorry,

SEE CAPS BELOW.

Regards,
Rob M.
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426

-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Rob Mueller
Sent: Monday, 15 August 2011 6:37 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] help to ID a part and its purpose

G'day,

Jim also recommends installing a switch across the boost solenoid. If you
loose your batteries completely you can switch it on, start the Onan and it
will provide 12vdc to the engine.

FROM THE HOUSE BATTERIES AND THE ONAN WILL KEEP THEM CHARGED THROUGH THE
CONVERTER.

http://www.gmcmhphotos.com/photos/showphoto.php?photo=39553

It's the one on the left marked Boost. ;-)

Regards,
Rob M.

-----Original Message-----
From: George Rudawsky

They're both solenoids (front and rear), and allow a large amperage to flow
through instead of overloading the boost switch.

JimB at the GMC Coop advises against just replacing them with a simple
starter solenoid, as they are not rated for continual use. However, I can't
think of many situations that you would keep them energized (except in an
emergency when you are using the house battery to run the engine electrics)
for more than a few seconds to start the engine with a dead front battery.

I believe that the rear one is only used to bypass a 50 amp circuit breaker
in the rear circuit.
--
George

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

Report message to a moderator

Previous Topic:	[GMCnet] John Wilsons FI Manuals Available
Next Topic:	[GMCnet] The DIY alignment kit is progressing nicely

Goto Forum:

-=] Back to Top [=-

Current Time: Thu Oct 10 11:26:10 CDT 2024

Total time taken to generate the page: 0.01372 seconds