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09-08-2014, 06:33 PM
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#1 |
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Registered User
Join Date: May 2014
Location: Granbury texas
Posts: 96
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70 gmc back up lights
I have a manual column shift and I found the backup switch on the trans. There is only one wire going to it. It is cut iff so no idea where it went. Research doesn't clearly show the wiring. The replacement switch shows 2 post. Any comments??
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09-08-2014, 07:53 PM
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#2 |
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Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,541
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Re: 70 gmc back up lights
The wire to the tranny is part of the tcv system. Transmission controlled vacuum switch. The wire clips to that post on the tranny which is the ground for the switch which should be up on the intake or on the firewall. It's function is to provide vacuum to the vac pot on the dizzy when you get into high gear.
Your backup switch is on the steering column down close to the firewall on top of the column. |
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09-08-2014, 07:56 PM
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#3 |
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Registered User
Join Date: May 2014
Location: Granbury texas
Posts: 96
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Re: 70 gmc back up lights
I dont have any of that stuff. I have a 250 cid and the vac for the dizzy comes of the carb.
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09-08-2014, 08:09 PM
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#4 |
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Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,541
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Re: 70 gmc back up lights
You very well might but know you know what it's for.
Did you find the back up switch? |
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09-08-2014, 08:12 PM
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#5 |
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Registered User
Join Date: May 2014
Location: Granbury texas
Posts: 96
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Re: 70 gmc back up lights
Have to go look. Haven't done that yet but I will. I want to them operational. Its a 3 sp manual. Will they make a difference?
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09-08-2014, 08:22 PM
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#6 |
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Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,541
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Re: 70 gmc back up lights
The tcv won't change anything for you.
Back up lights tell grandma in her prius you're backing up. Handy if you need to fight a ticket. Take a pic of your motor and firewall. Tcv might still be there or not. |
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09-08-2014, 10:40 PM
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#7 |
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Registered User
Join Date: May 2014
Location: Granbury texas
Posts: 96
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Re: 70 gmc back up lights
Geezer, My hat is off to you. I learned something. The tcv is long gone and the b/u switch is where you said. Not going to try and resurrect the tcv system. Thanks for the info!!
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09-09-2014, 07:09 PM
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#8 | |
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Senior Member
 
Join Date: May 2014
Location: Vancouver, BC
Posts: 472
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Re: 70 gmc back up lights
Quote:
I found the wires for mine but it still not obvious how it hooks up as nothing seems to move when I shift into reverse so I don't understand what would activate the switch.
__________________
Kitsbeach (Ken) 1967 C10 LWB (now SWB) Fleetside 6cyl Saginaw three-on-the-tree "No Frills" |
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09-09-2014, 07:19 PM
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#9 |
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Registered User
Join Date: May 2014
Location: Granbury texas
Posts: 96
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Re: 70 gmc back up lights
Took my switch out and it appears that part of the rank is broken off. Does anyone gave a picture of a good one and where x6an I buy one. My searches havent turned up anything.
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09-09-2014, 11:02 PM
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#10 |
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Registered User
Join Date: May 2014
Location: Granbury texas
Posts: 96
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Re: 70 gmc back up lights
That's not it. It mounts on top of tge steering column at the base near the firewall. Found some good pictures by doing a search. The LMC site sells them but its not a good picture. Wanted to be sure mine is broken.
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09-10-2014, 01:07 AM
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#11 |
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Senior Member
Join Date: May 2014
Location: Vancouver, BC
Posts: 472
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Re: 70 gmc back up lights
is this it.?
And do you know how it mounts or is it obvious.?
__________________
Kitsbeach (Ken) 1967 C10 LWB (now SWB) Fleetside 6cyl Saginaw three-on-the-tree "No Frills" |
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