Team Chevelle banner
  • Hey everyone! Enter your ride HERE to be a part May's Ride of the Month Challenge!

1 - 18 of 18 Posts

·
Registered
Joined
·
22 Posts
Discussion Starter · #1 ·
I have a 72 heavy chevy with the supersport dash. The dash has a factory tach that is not hooked up. I have bought numerous wiring diagrams hoping one would show how to hook it up. Well, to the best i can tell, there is a brown wire that comes out of the instrument panel (somewhere) that goes through the firewall and hooks to the negative of the coil. Can anyone give me some help as to where to look for this wire coming off the panel or what harness it is supposed to separate from. Also, is there anyway to check if it is the correct wire w/o just hooking it up and trying because i don't want to fry my panel. I have converted the car to HEI, does it still hook to the negative of the coil? Any help is greatly appreciated!
Jack
 

·
Premium Member
Joined
·
1,345 Posts
I believe you have it right. Brown wire to neg side of coil, even with HEI. Brown wire should then show up at pin #9 on 12 pin connector.
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #3 ·
DN, Thanks for the help. Unfortunately, that is the information that confused me in the first place. I have 4 wiring diagrams for 72 chevelles and only one shows the option gauges (tach) and all it shows is that it is a brown wire. So, I figured no problem just splice into the brown wire and hook it to the negative. Well, when i was standing on my head under the dash trying to get to the wires, i noticed the connector is actually numbered. In the wiring diagrams there are no numbers shown so i was just counting and the dots and the brown one happend to be the ninth i counted. Well, come to find out after using a mirror, the brown wire is actually in the pin labeled 3. So, my question is, is it actually the brown wire or is the wire in pin 9 which is green? I tried tracing them in the wiring diagrams and they both go off to other things (brown to ignition switch connector, green through another harness and eventually to the ignition switch connector also looks like it goes to the temp sending unit). I am stumped. Can anyone let me know for sure if it is the brown wire even though the number on the connector reads 3 and not 9? Looks like it could be 9 in wiring diagrams but on the connector itself, it says 3. Thanks for all your time and help.
 

·
Premium Member
Joined
·
1,345 Posts
Sounds like someone played with it.
Should be:
Pin# 1-light blue-left turnsignal
2 grey- dash lights
3 black/white-ammeter
4 black- ammeter
5 light green- high beam indicator
6 dark blue- oil pressure
7 pink- tach/temp/oil:fused power
8 tan- brake warning light
9 dark brown- tach
10 dark green- temp
 

·
Premium Member
Joined
·
1,345 Posts
PS Make it easier on yourself by taking out dash pad. Comes out easy- 6 screws- 2 in glove box.
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #7 ·
Still not lining up. Are the numbers you gave me for a 72? All my wires in my plug are in the same order as shown in the wire diagram, but the numbers are far different the ones you gave above. Am i possibly not looking at the right connector. I am looking at the one that plugs into the back of the circuit panel. The wires in my plug are as follows:
LBlue Gray Brown Open Pink Open
DBlue LtGreen DBlue Green Tan Tan
and the numbers on the plug are as follow:
1 2 3 4 5 6
12 11 10 9 8 7
The diagram shows the wires in the same order if i am looking at the correct plug...
Thanks for you time hopefully we can get this figured out!
 

·
Premium Member
Joined
·
1,345 Posts
That's the right plug. (there's only one 12 pin connector) same from 70-72. Original wire harness? Check this out-www.endrud.net/gauges/gauges.htm
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #9 ·
As far as i know it is the original wire harness. There aren't any signs to make me believe different. It is the same as what is shown in the all the wiring diagrams which leads me to believe it is original. Thanks!
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #10 ·
Perhaps some of it is out of a monte carlo??? is there any way to tell??? It has the round SS gauges. The three big gauges are...on the left is the gas guage, the middle is the speedometer, and the right is the tach. Just a thought...not sure if it makes a difference or not.
 

·
Premium Member
Joined
·
1,345 Posts
Your tach is where the clock should be. That would explain why the wires are different. Go by your diagram, it should work.
 

·
Premium Member
Joined
·
1,345 Posts
Looks like car didn't have a tach originally. Someone stuck one in where the clock was and couldn't get it hooked up.
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #13 ·
I plan on removing the dash pad this weekend to see if i can learn anything! What should i expect to see as far as the tach being a replacement? Will the old printed panel be cut possibly? If the tach is in there by itself, is there any way to hook it up indepently of the rest of the board? Can you wire on to the stud coming out of the back of it? Thanks!
 

·
Premium Member
Joined
·
1,345 Posts
Tach could be correct for your car, the problem is that it didn't have one originally. Therefore not the right harness. Splicing into the printed circuit board may be possible, but that one's over my head.There are certainly some P.H.D.s on this site tho. John Muha is certainly one of them.
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #15 ·
It looks like all the wires in my connector do the same as the wires in the connector shown on that website. Would switching the wires around to fit that plug do the trick? Also, can you get to that site? I tried going back to it again and it said it has been suspended. THanks, Jack
 

·
Premium Member
Joined
·
1,345 Posts
I don't think so, but not sure. That diagram is for the optional SS gauges, you have the standard ones. Keep trying that site, when you get it, print it.
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #17 ·
what exactly is the difference in the option ss guages and the standard ss guages? Does the standard guages have something other the speedometer, fuel, and tach?
 

·
Premium Member
Joined
·
1,345 Posts
Optional has tach, Small fuel gauge, small ammeter in place of idiot lites. Read post in "Restaration Corner" about switching from idiot lites to gauges. Not exactly the same, but you"ll get some more info.
 
1 - 18 of 18 Posts
Top