#1  
Old 04-25-2012, 07:59 AM
Rocky Racoon's Avatar
Rocky Racoon Rocky Racoon is offline
Senior Member
 
Join Date: May 2008
Location: St. Petersburg, FL
Posts: 241
Default Rally Gauge Wiring

I'm converting idiot lights to rally gauges in my 1968 GTO. I swapped the brown and tan wires for the gauges. I thought I read something about also cutting or disconnecting a green wire. Can anyone confirm this and let me know where this wire is? Should it be cut or disconnected?

  #2  
Old 04-25-2012, 12:48 PM
Verdoro 68's Avatar
Verdoro 68 Verdoro 68 is offline
Ultimate Warrior
 
Join Date: Jun 2003
Location: Clayton, CA
Posts: 2,806
Default

From the PY catalog:

Quote:
CONVERT FROM STD TO RALLY GAUGES: Locate #5 (tan) wire and the #7(brown) wire. (connector has each wire numbered). Swap these 2 wires. Green goes to temp sender, dark blue goes to oil sender. Clip the green wire going to the ignition switch on the column.
The comment about the green wire must have to do with '69-up since it refers to the ignition switch on the column. For '68 I believe it's just a straight tan/brown swap.

__________________
Ken
'68 GTO - Ram Air II 464 - 236/242 roller - 9.5” TSP converter - 3.55 posi (build thread | walk around)
'95 Comp T/A #6 M6 - bone stock (pics)

Last edited by Verdoro 68; 04-25-2012 at 12:53 PM.
The Following User Says Thank You to Verdoro 68 For This Useful Post:
  #3  
Old 04-25-2012, 01:14 PM
Old Goat 67's Avatar
Old Goat 67 Old Goat 67 is offline
Ultimate Warrior
 
Join Date: Jan 2004
Location: La., 67 GTO, Original Owner
Posts: 6,720
Default

The green wire on a 67 setup grounds the idiot light for testing the light on crank position. If left connected to the switch, it will BANG the temp gauge to full peg which will damage the gauge beyond repair in short order.

Charles

The Following User Says Thank You to Old Goat 67 For This Useful Post:
  #4  
Old 04-25-2012, 01:17 PM
Verdoro 68's Avatar
Verdoro 68 Verdoro 68 is offline
Ultimate Warrior
 
Join Date: Jun 2003
Location: Clayton, CA
Posts: 2,806
Default

Good to know, I suppose it is the same for '68 as well. In older threads about gauge swaps no one has mentioned clipping that wire.

__________________
Ken
'68 GTO - Ram Air II 464 - 236/242 roller - 9.5” TSP converter - 3.55 posi (build thread | walk around)
'95 Comp T/A #6 M6 - bone stock (pics)
  #5  
Old 04-25-2012, 07:51 PM
Rocky Racoon's Avatar
Rocky Racoon Rocky Racoon is offline
Senior Member
 
Join Date: May 2008
Location: St. Petersburg, FL
Posts: 241
Default

OK. So I just snip the green wire going to the ignition switch. Thanks

  #6  
Old 09-16-2019, 11:48 AM
Verdoro 68's Avatar
Verdoro 68 Verdoro 68 is offline
Ultimate Warrior
 
Join Date: Jun 2003
Location: Clayton, CA
Posts: 2,806
Default

Years later here I am doing the same swap. For posterity, here are some pics from the process. I found a pick works pretty well for releasing the pins from the harness.

5/7 swap






Disconnect the double green wire from the ignition switch.

Attached Thumbnails
Click image for larger version

Name:	IMG_7931.jpg
Views:	1383
Size:	46.3 KB
ID:	520259   Click image for larger version

Name:	IMG_7932.jpg
Views:	1819
Size:	55.1 KB
ID:	520260   Click image for larger version

Name:	IMG_7933.jpg
Views:	2110
Size:	48.7 KB
ID:	520261  

__________________
Ken
'68 GTO - Ram Air II 464 - 236/242 roller - 9.5” TSP converter - 3.55 posi (build thread | walk around)
'95 Comp T/A #6 M6 - bone stock (pics)
  #7  
Old 09-16-2019, 12:13 PM
Peter Serio's Avatar
Peter Serio Peter Serio is offline
Ultimate Warrior
 
Join Date: Mar 2000
Location: Columbus, OH 43209 USA
Posts: 2,647
Default

I would advise against cutting that green wire. As shown in Ken's photo above, the green wire for the temperature light/gauge signal on a '68 GTO is actually routed as 2 green wires joined together at the brass tab that plug into the back of the ignition switch. (The '68 Lemans-GTO ignition switch is a one year only switch.) The 2 wires are joined together but act as a single run (GTO-with gauges) current runs from the back of the temperature gauge, thru the printed circuit, into the green wire, out thru the firewall bulkhead to the coolant temperature sender.

Simply remove that brass tang from the plastic plug and either wrap it over with electrical tape or put a black plastic end on it. Fold the wires back over the main and secure it using a ti-wrap.

In 69 and 70 (if you add factory rally gauges to a car that came with warning lights), the green wire is "twinned" at the 12 slot plug-in right behind the gauge cluster. And the green wire at the ignition switch plug-in is just a single wire. (As a branch from a tree.) Exact same deal as '68 though you need to remove that green wire from the ignition switch connector or else your temperature gauge will have a very short life.
Attached Thumbnails
Click image for larger version

Name:	1968_GTO Rally Gauges Green-Wire Temperature Gauge plug-in.jpg
Views:	368
Size:	35.3 KB
ID:	520263   Click image for larger version

Name:	1969-70 GTO Rally Gauges Green Wire Plug-in at Steering Column_New.jpg
Views:	408
Size:	54.5 KB
ID:	520264   Click image for larger version

Name:	1969-70 GTO Rally Gauges Senders Oil and Water_New.jpg
Views:	344
Size:	36.1 KB
ID:	520265   Click image for larger version

Name:	1968 GTO Rally Gauges __02 L-H almost ready.jpg
Views:	681
Size:	49.0 KB
ID:	520266  

__________________
Peter Serio
Owner, Precision Pontiac
The Following 2 Users Say Thank You to Peter Serio For This Useful Post:
  #8  
Old 09-16-2019, 02:56 PM
Verdoro 68's Avatar
Verdoro 68 Verdoro 68 is offline
Ultimate Warrior
 
Join Date: Jun 2003
Location: Clayton, CA
Posts: 2,806
Default

Quote:
Originally Posted by Peter Serio View Post
I would advise against cutting that green wire.
Good tip, I'm always hesitant to cut any original wires.

__________________
Ken
'68 GTO - Ram Air II 464 - 236/242 roller - 9.5” TSP converter - 3.55 posi (build thread | walk around)
'95 Comp T/A #6 M6 - bone stock (pics)
The Following User Says Thank You to Verdoro 68 For This Useful Post:
  #9  
Old 09-16-2019, 04:20 PM
OG68's Avatar
OG68 OG68 is offline
Ultimate Warrior
 
Join Date: Dec 2011
Location: Chula Vista, CA
Posts: 1,475
Default

Wow. Another item to put in my notebook. But...
When I did this mod back in the mid eighties I left the green wires in place in the ignition switch. (Just checked my original harness) Drove the car on a daily basis for 5 or 6 years and never had a problem with the Temperature gauge.
But why tempt fate the second time around. I'll pull the wires from the switch when it all gets assembled.

No, I better go do it now while the harness is out of the car and its still fresh in my mind.

Thanks Peter

__________________
Ed

1968 GTO (Thanks Mom)
2006 Silverado
2007 Cadillac SRX
2015 Chevy Express

  #10  
Old 10-08-2019, 10:20 AM
killakev's Avatar
killakev killakev is offline
Senior Chief
 
Join Date: Nov 2013
Posts: 273
Default

Great thread. I saved it as a PDF for that day that I put my rally gauge cluster in!

  #11  
Old 10-13-2023, 05:47 AM
nh68gto's Avatar
nh68gto nh68gto is offline
Ultimate Warrior
 
Join Date: Jun 2005
Location: Hudson , NH
Posts: 1,639
Default

Hey guys. Just doing this too. So 69-70 do the double green wires get pulled from the connector?

Also read Teflon tape is a no no. True ?
How do you seal the sensors ?

__________________
Send it! It’s going home on a trailer.
  #12  
Old 10-14-2023, 03:26 PM
Peter Serio's Avatar
Peter Serio Peter Serio is offline
Ultimate Warrior
 
Join Date: Mar 2000
Location: Columbus, OH 43209 USA
Posts: 2,647
Default green wire to remove from this plug-in

On that green wire I have seen it made with the "twin" on the plug-in at the back of the gauge cluster so there is just one lone green wire that goes over to the ignition switch.

This would most likely be on a 69 or a 70 GTO. In that case leave your existing twin green wires at the gauge housing (plug-in) alone and remove this single green wire (blue arrow). Fold the loose green wire back over itself and wrap it with electrical tape.

NOTE: You may need to lower the steering column to access the plug-in at the ignition switch.
Attached Thumbnails
Click image for larger version

Name:	Wiring green wire to Ign switch=69-70.jpg
Views:	73
Size:	35.7 KB
ID:	621673  

__________________
Peter Serio
Owner, Precision Pontiac
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 02:56 AM.

 

About Us

The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.

 




Copyright © 2017