Home » Public Forums » GMCnet » Rewiring power to the Air Compressor EL 1. (Relays, Breakers, 10ga wires)
| Rewiring power to the Air Compressor EL 1. [message #286015] |
Fri, 28 August 2015 08:02  |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
Karma: 6
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Senior Member |
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Greetings,
Im in the process of installing a rebuilt Dana compressor in the Royale (77 with the EL 1 system). In reviewing several postings and talking with some folks, Ive read its better to rewire the compressor to the rear battery (Onan battery) in the coach, so there is less voltage drop from the front battery some 20 plus feet away. Its a short run from the back battery to the compressor which sits in the rear driver side pretty darn close to the battery.
Can anyone point me in the direction of either a how to, or a write up of how this is properly done? Please. I have done a number of searches and have only found a few mentions of it, but not much that has photos or specifics.
I have read to use 10 gauge wire for both the power and ground. Need a 30amp relay, fuse and possibly a circuit breaker as well? Running power from the rear battery seems pretty straight forward. Where I get lost is where to plug that into on the pressure switch. (I have a stock Penn switch there right now). I read is the brown wire in the bundle going back that needs to be clipped and rewired there but have not verified yet.
Any help or photos would be great, Thank you again.
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
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| Re: Rewiring power to the Air Compressor EL 1. [message #286030 is a reply to message #286029] |
Fri, 28 August 2015 11:34  |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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The oem is a 30 amp circuit breaker located in the top position of the fuse box in the glove box behind the plate with a screw in it.
SONICJK wrote on Fri, 28 August 2015 12:26I don't have any photos but it's just as simple as you say it is.
The brown wire is power to the pressure switch.
The switch is just s simple contactor that disconnects power at xxpsi and reconnects it at xxpsi.
I changed over to a new version that has the relay built in to simplify things.
http://www.amazon.com/Viair-90111-Pressure-Switch-Relay/dp/B000FQ793A/ref=sr_1_1?ie=UTF8&qid=1440778998&sr=8-1&keywords=viair+pressure+swi tch
Check the connections on your original pressure switch, mine were corroded and broke when I tried to remove the wires.
Other than that, just run a power and a ground wire (ground to chassis) with an inline fuse rated for your load (I'm not sure what the stock dana pulls, I'm guessing a 15A would be a good fit) The shorter the power wire the better, but if you're using a 10ga wire you should be just fine.
C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] Rewiring power to the Air Compressor EL 1. [message #286033 is a reply to message #286030] |
Fri, 28 August 2015 11:58 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Wayne,
As Chuck B has pointed out GMC uses a 30 Circuit Breaker in the front fuse panel, a 15A fuse is a little light and a 20 A could be marginal too. That is so the breaker will reset and not leave you searching for a 30 fuse to continue down the road. I would suggest that you include a 30 A circuit breaker in your conversion and use no fuses. The original pressure switch contacts are rated for 30 amps so the 30/40 amp relay would be optional. You also need to insure that the rear batteries are receiving proper charging from the front as you could run them down and leave you without generator starting power if you are on the road all day and not charged by your converter/charger.
J.R. Wright
GMC Great Laker MHC
Newsletter Editor/Publisher
GMC Eastern States
GMCMHI
78 GMC Buskirk 30’ Stretch
75 GMC Avion (Under Reconstruction)
Michigan
> On Aug 28, 2015, at 12:34 PM, Charles Boyd wrote:
>
> The oem is a 30 amp circuit breaker located in the top position of the fuse box in the glove box behind the plate with a screw in it.
>
>
> SONICJK wrote on Fri, 28 August 2015 12:26
>> I don't have any photos but it's just as simple as you say it is.
>> The brown wire is power to the pressure switch.
>>
>> The switch is just s simple contactor that disconnects power at xxpsi and reconnects it at xxpsi.
>> I changed over to a new version that has the relay built in to simplify things.
>>
>> http://www.amazon.com/Viair-90111-Pressure-Switch-Relay/dp/B000FQ793A/ref=sr_1_1?ie=UTF8&qid=1440778998&sr=8-1&keywords=viair+pressure+swi tch
>>
>> Check the connections on your original pressure switch, mine were corroded and broke when I tried to remove the wires.
>>
>>
>>
>> Other than that, just run a power and a ground wire (ground to chassis) with an inline fuse rated for your load (I'm not sure what the stock dana
>> pulls, I'm guessing a 15A would be a good fit) The shorter the power wire the better, but if you're using a 10ga wire you should be just fine.
>
>
> --
> C. Boyd
> 76 Crestmont
> East Tennessee
>
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: Rewiring power to the Air Compressor EL 1. [message #286048 is a reply to message #286015] |
Fri, 28 August 2015 15:38 |
nchapekis
Messages: 165
Registered: February 2004
Location: Ypsilanti, MI
Karma: 0
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77Royale wrote on Fri, 28 August 2015 09:02Ive read its better to rewire the compressor to the rear battery (Onan battery) in the coach, so there is less voltage drop from the front battery some 20 plus feet away. Its a short run from the back battery to the compressor which sits in the rear driver side pretty darn close to the battery.
I'm no electrician so someone chime in here, but wouldn't the voltage drop be larger doing it this way, since the wiring would have to run to the front control panel first?
Nick Chapekis
Ypsilanti, MI
former owner - 78 Kingsley
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| Re: [GMCnet] Rewiring power to the Air Compressor EL 1. [message #286056 is a reply to message #286033] |
Fri, 28 August 2015 16:41 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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I guess I should add that the air compressor needs to be on a switched circuit so it won't fire up on demand when parked or in storage. You could power the relay control off the ignition switch to control the house circuit to the compressor. Or put a dedicated switch, maybe lighted, if your memory is better than mine.
powerjon wrote on Fri, 28 August 2015 12:58Wayne,
As Chuck B has pointed out GMC uses a 30 Circuit Breaker in the front fuse panel, a 15A fuse is a little light and a 20 A could be marginal too. That is so the breaker will reset and not leave you searching for a 30 fuse to continue down the road. I would suggest that you include a 30 A circuit breaker in your conversion and use no fuses. The original pressure switch contacts are rated for 30 amps so the 30/40 amp relay would be optional. You also need to insure that the rear batteries are receiving proper charging from the front as you could run them down and leave you without generator starting power if you are on the road all day and not charged by your converter/charger.
J.R. Wright
GMC Great Laker MHC
Newsletter Editor/Publisher
GMC Eastern States
GMCMHI
78 GMC Buskirk 30' Stretch
75 GMC Avion (Under Reconstruction)
Michigan
> On Aug 28, 2015, at 12:34 PM, Charles Boyd wrote:
>
> The oem is a 30 amp circuit breaker located in the top position of the fuse box in the glove box behind the plate with a screw in it.
>
>
> SONICJK wrote on Fri, 28 August 2015 12:26
>> I don't have any photos but it's just as simple as you say it is.
>> The brown wire is power to the pressure switch.
>>
>> The switch is just s simple contactor that disconnects power at xxpsi and reconnects it at xxpsi.
>> I changed over to a new version that has the relay built in to simplify things.
>>
>> http://www.amazon.com/Viair-90111-Pressure-Switch-Relay/dp/B000FQ793A/ref=sr_1_1?ie=UTF8&qid=1440778998&sr=8-1&keywords=viair+pressure+swi tch
>>
>> Check the connections on your original pressure switch, mine were corroded and broke when I tried to remove the wires.
>>
>>
>>
>> Other than that, just run a power and a ground wire (ground to chassis) with an inline fuse rated for your load (I'm not sure what the stock dana
>> pulls, I'm guessing a 15A would be a good fit) The shorter the power wire the better, but if you're using a 10ga wire you should be just fine.
>
>
> --
> C. Boyd
> 76 Crestmont
> East Tennessee
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] Rewiring power to the Air Compressor EL 1. [message #286082 is a reply to message #286056] |
Fri, 28 August 2015 21:44 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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Use the signal from the factory pressure switch to control the relay, terminal #86. Ground on terminal #85. I put a switch in that connection so I can turn off the compressor whenever i want manual control. I used the light in the switch to tell me when the pressure switch is sending power to the relay. The pressure switch is supplied by ignition power already, so it won't come on when the ignition is off. Connect the compressor positive lead to #30 on the relay, and the power feed from your battery through a circuit breaker to the #87 terminal on the relay.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: Rewiring power to the Air Compressor EL 1. [message #286083 is a reply to message #286015] |
Fri, 28 August 2015 21:49 |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
Karma: 6
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Well I looked at it tonight, There is a stock AC Delco Relay already in there down below the air tank. It has a 10ga green and brown wire on the one side and a smaller yellow and I think black wire on the other. With stock connectors. The green and brown run up to the pressure switch. SO is this relay acceptable to tap into? I suppose the question becomes leave that one alone? and wire in another relay from the Onan Battery.
To be honest, aside from a slow air leak somewhere, everything back there works. Im wondering if I mess with it at all? Under the if its not broke category.
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
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| Re: Rewiring power to the Air Compressor EL 1. [message #286089 is a reply to message #286083] |
Fri, 28 August 2015 23:35 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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You have exactly the same setup that I have with my 1976 PB and Electrolevel l. I have never seen a GM wiring diagram with that relay installed and it is obviously a factory installation. I have never needed to get into that circuit but I assume that the relay coil is controlled by the accessory position of the ignition switch. I do not know where they get the power for the compressor from.
I need to dig around and see if I can find a 1976 or 1977 wiring diagram with electrolevel 1 installed.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Rewiring power to the Air Compressor EL 1. [message #286118 is a reply to message #286015] |
Sat, 29 August 2015 20:53 |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
Karma: 6
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Senior Member |
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Thanks Ken if you can find a diagram, The MM I have only lists out the 78 model with EL II. I thought maybe a page had gone missing in my manual.
There is reference to the relay, and a photo in the manual however. I want to say it said a dual function relay... But not sure. I check it out in the am.
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
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| Re: Rewiring power to the Air Compressor EL 1. [message #286212 is a reply to message #286118] |
Sun, 30 August 2015 22:37 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
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Ok I found a diagram. It is labeled 77 / 78 transmode with Electro level 1. I have no idea where I got it, but it does show the relay. The coil of the relay is wired to the control switches up front. The power source lead (30 amp) is connected to a 30 amp fuse or circuit breaker up front.
So to do your upgrade all you need to do is remove the brown 12 gage lead from the relay Normally Open point (pin #3) and replace it with a new 10 ga. wire wired to the house battery side of things through a fuse of Circuit Breaker. Also you need to remove the ground lead from the motor and attach a new one to the house battery ground which is the aluminum body of the coach.
I also just found the wiring diagram with the relay on Bill Massey's GMC site here:
http://bdub.net/wirediagrams/77-78-chassis-electrolevel-I.pdf
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Rewiring power to the Air Compressor EL 1. [message #286246 is a reply to message #286015] |
Mon, 31 August 2015 10:15 |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
Karma: 6
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Thank you So much Ken. and on behalf of the other EL 1 Royale owners out there who may do this with the air compressor.
I will be sourcing some 10Ga wire in line 30amp fuse. and a fresh Ground wire. I will probably replace the relay with another new 30amp just because Im already in there. I know that relay is still good, but its old.
on a side note, I found some of the plastic fittings leaky on both sides of the coach near the bags. That was the slow leak I have (or at least a few of them) now that I have the new compressor installed. DOT fittings are pricy. but hopefully its the last time I will need to do it.
Thanks again, and Billy too for posting it. As I mentioned my MM for the 77-78 does not appear to have that diagram. It goes right to the Transmode for the 78 EL 2 diagram which is different. Im not sure if the PO accidentally removed it or it fell out...
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
[Updated on: Mon, 31 August 2015 10:17] Report message to a moderator |
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| Re: [GMCnet] Rewiring power to the Air Compressor EL 1. [message #286254 is a reply to message #286246] |
Mon, 31 August 2015 11:41 |
k2gkk
Messages: 4452
Registered: November 2009
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Try to locate "MARINE" grade wire for your project. It generally uses smaller individual strands for better flexibility and they are "tinned" to reduce the likelihood of corrosion from moisture.
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~ ~ Since 30 November '53 ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ Member GMCMI and Classics ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ~ TZE166V101966 ~ ~ ~ ~
~ ~ ~ '76 ex-Palm Beach ~ ~ ~
~~ k2gkk + hotmail dot com ~~
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> Date: Mon, 31 Aug 2015 09:16:00 -0600
> To: gmclist@list.gmcnet.org
> From: rojewsw@gmail.com
> Subject: Re: [GMCnet] Rewiring power to the Air Compressor EL 1.
>
> Thank you So much Ken. and on behalf of the other EL 1 Royale owners out there who may do this with the air compressor.
>
> I will be sourcing some 10Ga wire in line 30amp fuse. and a fresh Ground wire. I will probably replace the relay with another new 30amp just because
> Im already in there. I know that relay is still good, but its old.
>
> on a side note, I found some of the plastic fittings leaky on both sides of the coach near the bags. That was the slow leak I have (or at least a few
> of them) now that I have the new compressor installed. DOT fittings are pricy. but hopefully its the last time I will need to do it.
>
> Thanks again.
>
> --
> 77 Royale, Rear Dry Bath. 403.
> Mid Michigan
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