Just finished up installing new wireing on 66 coupe. Lots of problems any suggestions?

1) When I hook up battery two green blinker lights and red one in center is on.
2) turn on ign, water temp guage pegs
3) noticed black ground wire on alternater is hot(12v)
4) lots of things dont work, headlights,wipers,brake lights(checked switch under dash OK 12v when pedal pressed)

Things that work

Courtesy lights
tail lights
electric antena
dash lights and dimmer
starter
radio

Thanks in advance KC

 

KC, there is a black ground wire with female connector that connects to the top of the instrument cluster above the tach.

There is a dark brown hot wire with a female connector that connects to a capacitor under the oil gauge. If you mistakenly connect the dark brown wire to the ground location above the tach (and thus connect the ground wire to the capacitor), strange things can happen.

You may wish to confirm that first.

Jeff

 

Hi Jeff, I double checked that again this morning, looks to be correct. Thanks KC

 

Wow. That be a mess of bad!!! I have a 65 so that's the schematic I am working off of but will try to help you some.

1) the red light is the high beam light. Disconnect the high beam switch and see if it goes out. Also check and see if there is 12V on the Black/Light Blue wire all the time. It should be hot when the headlight switch is on and cold when the switch is off. Are the two blinker lights blinking or steady?

2) Disconnect the input to the temp gauge at the sensor on the intake manifold. Temp gauge change state? If it doesn't, pull fuse #1. That will shut down the gauges. See if the dark green wire is grounded (with the other end of it still disconnected from the sensor). If it is, you have a short in that wire which is why your gauge is pegged.

3) Is the ground wire itself is hot or is the ground post on the alternator hot? With the ignition off the only wire on the alternator that should be hot is the big red one. The Dark Blue and the Black/White wire should not be hot and the ground should never be hot.

4) I would pull fuses to isolate some of your systems cause you have a lot of stuff that isn't working and is on different lines. Fuse #1 controls the gauges and emergency brake light. Fuse #6 is the Brake light fuse. I would also disconnect the wiper motor and washer connections.

The first thing I would try to fix is the hot alternator issue. That one bothers me in as much as there are direct lines from the battery to the alternator which could get way too hot and melt things.

Let us know how some of these checks worked out.

Geek

 

Geek,

1) High beam, blue and two green wires 12v even with all fuses pulled
2) Temp guage sender disconnected still the same. Must have something to do with guage. Will try to unplug gauge and see what happens.
3) ground wire on alternater has 12v,red one ok, also noticed ground wire on regulator 12v also, this is with all fuses pulled. Seems like all ground (black wires under the hood are hot even the black ones on the headlight harness plug.
4 green blinker lights and red light on center of dash is on steady,even with all fuses pulled

This is a brand new harness, dont know what brand, got it with car. May be junk!!!!!

any thoughts KC

 

Man that is something else!!

Did the car work correctly before you installed the harness? Is it the main cockpit harness that you replaced or did you do the engine bay harness and rear harness as well?

G

 

Let's see if we can't cut down on some of the possible issues.

Pull firewall connector #1 on the passenger side of the car (the left connector as you are facing them looking down sitting side by side) . That should separate the battery feed to pretty much everything in the car but still leaves the horn relay hot as well as the red wire to the alternator. Now measure and see if the ground wire to the alternator is still hot. If it is, our problem is somewhere in the engine bay wiring. If it isn't, then we can reconnect the firewall connector and start isolating stuff in the cockpit.

G

 

Hey G, I got this car all in pieces, so Im trying to put it all together after 25 years of being all apart. Its like putting together a puzzle. I finally figured one of my problems out. The ground wire by the horn relay was hook up to the hot terminal. Soooo now the lights on dash is all ok. Headlights work now !!!! But brake lights still dont work, tail lights work though, and water temp still not working right( brand new one). Wipper motor not working either, bench tested it with the dash before I installed and it worked, but dont work now. LMK if you have any othe ideas!!!! Thanks for all your help KC

 

That was a good find, congratulations.

That sounds like a bad brake light switch.

On the temp gauge - if your temp sender is internally shorted, the temp gauge will peg to the HOT side when you turn the key on. Can you measure the Ohms of resistance between the center pole of the temp sender, and the side of the temp sender?

Regarding the wiper motor, the wiring on that is tricky. Also it could be a bad switch.

Jeff

 

Excellent!! Will think about it a bit. Brake lights and tail lights are actually on two different circuits so that helps sort some issues. No problem about help. I still haven't helped as much as those here have helped me so I got a lot to make up for.

Jeff is right about the wiper, wiper switch and the temp sender shorting out pegging the gauge stuff. But if you pulled the wire off the sender and the gauge still pegs - it's not a shorted sender.

Will sit down with a beer tomorrow afternoon and see if something strikes me.

G

 

Ahh, I didn't pick up on that part. The gauge is supposed to be grounded to the cluster. Did you have the cluster apart, did you properly ground it?

I once worked on a mid-year that had an insulator installed that prevented the temp gauge from grounding to the cluster. The temp needle read over-high when the car was powered.

 

Spend a few bucks and buy Dr. Rebuilds wiring schematic for your car. Also there is a guy on the forum who will send you via Email a schematic for your car, but not near as helpful as Dr. Rebuids. Everything is color coded and on large plastic like sheets.

You'll be using it multiple times over the life of your Vette.

http://docrebuild.com/oosoez.html

 

Ok ground wasnt that good on the wiper motor. got that working!!!! Only brake light and water temp guage to go!!!! May be grounds on both????? w will let you know. Thanks for all of yoyr inputs guys KC

 

How many ohms should the sender be? I have about 500, does that sound about right? Thanks KC

 

That sounds like a good sender. The sender works by reducing the resistance as the engine warms up. 500 Ohms is about 85 degrees, 123 Ohms is 180 degrees, 83 Ohms is 211 degrees, etc.

So if your sender had 0 Ohms that would show a shorted sender.
However as Geek reminded me, you've already shown the temp gauge is pegged even with the sending wire disconnected which takes the sender out of the equation anyway. So I'm leaning towards the gauge or a gauge grounding problem.

 

My notes say the sender is about 900 ohms when cold and approximately 115 ohms at 200 degrees. But if there is 500 there then that should not peg the meter. With the green wire to the sender still disconnected from the sender and the plug disconnected from the temp meter, see if the wire itself is shorted to ground. (Have to disconnect it from the temp gauge so you don't read back through the gauge.)

Do your turn signals work? (Brake lights go through the turn signal switch)

G

 

Yes turn signals work. If I have to ground the guage, do I run a ground wire from one of those mounting studs, or one of the terminals(which color)? Is it possible I have put on the male connectors wrong on the back of the guage and the wires are backwards? What do you think? Well off to work(real job) for now check back with you guys latter. KC

 

So if the rear lights are working for the turn indicators that means the ground back there is good. We also know that the connection between the steering column connectors, the rear body connector, and the brake lights are good because the turn indicators worked. Best thing I think is to trace back the 12 volts from the brake switch that you said was good and see if the turn indicator switch is getting 12volts to turn on the brake lights or the switch is messed up and won't let the signal go out when it's in the middle position.

On the steering column there are two connectors. Disconnect them and find the black wire with a white stripe. That is the wire from the brake switch to the turn signal switch. Press the brake and see if you get 12 volts on it. If you do then we move on. If you don't, the problem is between the switch and the steering column connector.

If you do then reconnect the steering column connector and go to the rear body connector that's on the left side of the car up behind the light switch. Make sure the turn indicator is in the middle position (no turn selected). Disconnect the rear body connector and on the side of the connector that comes from the main harness, find a black wire with a yellow stripe. Press the brake pedal and you should get 12 volts there. Do the same thing on that same connector with the dark green wire. Those two wires go to the left and right side brake lights and work when you select the turn indicator. Hopefully they don't work when it's neutral and we can point straight to the turn signal switch as an issue.

G

 

Just thought of something regarding the temp gauge. When I first got my car, the temp gauge would peg out intermittently but all the wiring checked good. Turned out it was that third post on the back of the gauge that isn't used. That post would sometimes touch the case of the gauge and that's when it pegged. Put a meter on that third post and see if it reads a direct short. If it does - that's your problem.

G

 

Been following along and thougth I'd throw in my 5 cents on temp gage issue.

1. Be sure you have a good connection on the sending unit on the motor - I've seen some where the wire is good but the connection to the sending unit is bad.

2. The sending unit itself may not be calibrated right. There are a number of ones on the market - a lot of the current over the counter are junk when new.

3. If you are using an aluminum intake and put on to much thread sealant that could also present a problem.

Maybe try to borrow a sender that you know works and try that out. Another option is run a temp wire from the sendor to the gage and see if the problem goes away. Really sounds like a ground problem at the gage to me.

Good Luck !