75 Wiring Help
Thread Starter
6th Gear
Joined: Sep 2008
Posts: 6
Likes: 0
From: Pittsburgh Pa
75 Wiring Help
Hi, i'm replacing the tach in my dad's 75 vette, when i was under the hood i came across some problems. The 1st problem is, the brown wire that goes to the dist. has no tach filter, their should be one bolted to the intake manifold under the dist. is that right ? The 2nd problem is, a orange wire from the harness that goes no where, looks like its been cut and was wrapped in masking tape. Any help would be great. I have pics if i can figure how to post them in this message. 
Melting Slicks
Joined: Feb 2006
Posts: 2,092
Likes: 5
From: Fayetteville Arkansas
yeah gonna need some pics and more detail... for sure that orange wire could go anywhere... it's a 12v power source and could go to the clock or the courtesy lights or a number of other things... do you have a wiring diagram? get us some more detail or pics and maybe we can help...
good luck,
Sully
good luck,
Sully
Racer
Joined: May 2007
Posts: 370
Likes: 0
From: Cherry Hill N.J.
75 wiring help
You are right... the brown wire should have a filter on it and goes to the dist...
The other wire probably goes to washer pump on bottom of washer reservoir.
The other wire probably goes to washer pump on bottom of washer reservoir.
Last edited by BHRIG; Sep 10, 2008 at 06:44 PM. Reason: better information
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
Hi, i'm replacing the tach in my dad's 75 vette, when i was under the hood i came across some problems. The 1st problem is, the brown wire that goes to the dist. has no tach filter, their should be one bolted to the intake manifold under the dist. is that right ? The 2nd problem is, a orange wire from the harness that goes no where, looks like its been cut and was wrapped in masking tape. Any help would be great. I have pics if i can figure how to post them in this message.
This should help, it's Durango Boys istruction site.
http://photos.imageevent.com/durango...g%20Images.pdf
Thread Starter
6th Gear
Joined: Sep 2008
Posts: 6
Likes: 0
From: Pittsburgh Pa
75 Wiring Help
Thanks guys, got a pic loaded but its big. The orange wire i put on top of the spark plug wire comes right from the harness. Its really long and able reach the other side of the engine compartment. Now the brown wire for the tach, should the tach filter be right there bye the dist. or down along the fire wall where the harness clips in under the brake booster ? Appreciate the help ! 
Drifting
Joined: May 2005
Posts: 1,629
Likes: 4
From: Somers CT
The tach filter is supposed to be bolted to the intake in that tapped hole just under the edge of the dis cap in your last picture. What is that silver can in the picture? Looks like it's threaded into the dist shaft area right under the red power lead to the dist.
Drifting
Joined: May 2005
Posts: 1,629
Likes: 4
From: Somers CT
I'll look at mine later tonight if you don't get an answer first on the wire.
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Drifting
Joined: May 2005
Posts: 1,629
Likes: 4
From: Somers CT
I looked at mine last night, the orange wire is either the alarm or the blower. Based on the size in your picture I'm betting it's the alarm
Thread Starter
6th Gear
Joined: Sep 2008
Posts: 6
Likes: 0
From: Pittsburgh Pa
update
sorry been gone for a couple of days, just wanted to post an update.
Well i checked all the suggested locations for the orange wire but the tranny, everything seems to be in place. Security lock orange and red, blower black and purple, just have to keep tracing. Now the real pain, installed the new tach board and nothing, at a loss. all the trim pieces where missing screws or mixed. has 2 be because of the person that rigged in a junky 8track radio. found a stock radio on ebay for $99 thinking about buying it thank god the wires are still there. Heres a pic of my nightmare. thanks for all your suggestions.
Well i checked all the suggested locations for the orange wire but the tranny, everything seems to be in place. Security lock orange and red, blower black and purple, just have to keep tracing. Now the real pain, installed the new tach board and nothing, at a loss. all the trim pieces where missing screws or mixed. has 2 be because of the person that rigged in a junky 8track radio. found a stock radio on ebay for $99 thinking about buying it thank god the wires are still there. Heres a pic of my nightmare. thanks for all your suggestions.
Drifting
Joined: May 2005
Posts: 1,629
Likes: 4
From: Somers CT
I feel your pain
See below. On Tach board, only suggestion I have is make sure it's grounded but others might have a better idea. I bought a laminated wiring diagram from Dr. Rebuild, I'll look to see where I put the darn thing and scan orange wire locations for you later.
See below. On Tach board, only suggestion I have is make sure it's grounded but others might have a better idea. I bought a laminated wiring diagram from Dr. Rebuild, I'll look to see where I put the darn thing and scan orange wire locations for you later.
Burning Brakes
Joined: Mar 1999
Posts: 1,047
Likes: 3
From: CA
does your heater fan work on the highest speed? On some cars there is a relay for the high speed that is powered by a connection on the horn relay. The wire connecting the two crosses over the motor along the firewall similar to what you have in the photo. Best bet is to get a schematic.
Instructor
Joined: Jul 2008
Posts: 100
Likes: 0
From: Long Jetty NSW
I might be from across the other side of the planet, but the issues are similar.
I couldn't figure out the orange wire either, but it ended up being for the kickdown on the tranny. The wire seemed too long, but the type of connector on the end (which you don't have) gave the game away.
I also replaced the PCB on the Tach, but it still didn't work. In my case the phenolic (insulating) washers were missing from the two mounting screws, so there were some serious short circuits. I used some "O" rings and fixed the problem. By the way, my engine wasn't finished, so I temporarily hooked the tach to another car I have with a Chevy engine to see if it worked or not. I've included a picture of my own nightmare, made worse by the addition of alarm, front & rear parking sensor and central locking wiring.
I couldn't figure out the orange wire either, but it ended up being for the kickdown on the tranny. The wire seemed too long, but the type of connector on the end (which you don't have) gave the game away.
I also replaced the PCB on the Tach, but it still didn't work. In my case the phenolic (insulating) washers were missing from the two mounting screws, so there were some serious short circuits. I used some "O" rings and fixed the problem. By the way, my engine wasn't finished, so I temporarily hooked the tach to another car I have with a Chevy engine to see if it worked or not. I've included a picture of my own nightmare, made worse by the addition of alarm, front & rear parking sensor and central locking wiring.
Thread Starter
6th Gear
Joined: Sep 2008
Posts: 6
Likes: 0
From: Pittsburgh Pa
Good news
Good news, got the tach working, turns out that it was the washers that bob suggested,(had them installed backwards lol) very greatful. The car idles around 13/14 rpm, only prob. the needle doesn't zero out when u turn the car off, only when you turn the key back too accesories. Think this because the tach filter is missing? I'll check the orange wire for the tranny kickdown after i get the interior back together. I have to move the car to the other side of the garage/more room to jack and get under it. Thanks again for all the help. Best forum on the net!
