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Discussion Starter #1
I just got my car back from 6 months at the paint shop. My blinkers, brake lights, head lights and hazard lights work. My running lights and dash lights do not work but dome light does.
I work on Sat. so I will check this posting Sat.
night and see what I can figure out Sun. Oh the car is a 70 chevelle,
THANKS, Ken in Forney, Texas
 

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Check the tail light fuse. It provides power to both the running lights and the dash lights. Dirty fuse clips are a probable cause.
 

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Discussion Starter #4
It's 6:10 pm I took the fuse out and got a little file and cleaned the clips. They really looked fine though. I put the fuse back and still no tail lights or dash lights. Most every thing has been replaced on this car in the 4 years I have had it. My problem has to be some thing the paint guy did. He has no clue. He took the car apart and painted each piece by itself. Could my problem be a mashed or pinched wire some where? I am going to go back now and take each bulb out and see if I can get anything to work. Thanks John for any help you can give
 

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Bigdaddy, jump a wire from a "hot" fuse or from battery to the dash/tail light fuse socket to see if you get the lights if powered from a different source. If yes, then the problem is in the power feed to the fuse. If no, then your problem is downstream to the fuse block.
 

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Discussion Starter #7
I checked at both ends of fuse and I got 12.04 volts and the battery I got same reading. For what it is worth about 2 years ago I installed new wiring kit from firewall forward so wires are not 35 years old. They were in bad shape around motor. (melted) I did install my weather stripping kit today so I could say I got something finished. I go back and forth on this wiring problem because it gets me depressed. I am working on this car by myself so I appreciate any advise, because I am terrible at electrical problems. Thanks all, Ken
 

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Did you dig into the fuse clips? Often times people measure voltage by touching the probe to the metal part of the fuse. Wrong place. It's the clips one should measure.
 

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Discussion Starter #9
I did measure off the fuse part the first time. I did it again and put the volt meter probe between the clips and the plastic edges and did not touch any part of the fuse. I still get 12 volts on each side. I got a wiring diagram of a 70 chevelle and it looks like a brown wire runs the parking lights. Can I splice a wire to the brown wire to battery to see if it lights everything or would that not accomplish anything? I checked all bulbs,(their OK) still got blinkers and brake lights. Tonight this is all I messed with. Thanks for any help.
 

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There appears to be a problem in the Mitchelle wiring diagram for 1970 so use 1971. I show the bulk head connector has a row of
(2x Tan) (2x Brown) (Brown) (2x Lt Gr) on the inside.
A) tan is ground for brake light
B) brown Alt Light ground via regulator
C) brown Front Running Lights
D) Lt Gr High Beam to front bulbs

Check for juice on brown wire at headlight switch. If that's good find the hi beam Lt green at the bulk head on the inside. Right next to that should be a double brown wire for the running lights. If you want to juice that wire please do so through a 10A fuse for safety.
Those answers should tell you everything you need to know.

Mark
 

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Check the orange wire on the headlight switch. Orange is the input to the switch and brown (tail lights) and green (dash lights) are outputs from the switch.
 

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Discussion Starter #12
I pulled the black wire housing off the headlight
switch. The orange wire showed 1.1 to 1.2 volts.
I checked the bigger red wire coming to the housing and it showed 12 volts. I then run a small wire from the red wire to the brown and the
green wire at different times. I then did get dash lights and then tail lights. How do I properly fix this? Do I run a new wire from back of fuse box to where the orange wire clips on the
headlight switch? At least now we can see where a
problem is. Thanks to John and everbody else.

Ken A. in Forney,Texas
 

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Maybe John can answer that one for you. The Orange wire is fused from the fuse box. It looks like the Dk Gr goes to the dash light fuse which then comes out Grey to the dash lights? Is that correct?
 

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Originally posted by bigdaddy46:

switch. The orange wire showed 1.1 to 1.2 volts.
Still thinking your tail light fuse clips are dirty. It's rare but perhaps the crimp joint on the orange wire socket, at the headlight switch, is acting up. Get the orange line up to 12 volts and things will work.
 

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Discussion Starter #15
I got a tiny file and really worked the fuse clips over. Now I do have 12 volts on the orange wire at headlight switch. I plugged it in and still no tail lights and dash lights. I unplugged it and ran a wire from the red wire and
can make both dash and tail lights work. Even though I have 12 volts at the orange wire I can not do the same there by bypassing the switch. The orange wire has 12 volts on its own but when I run a wire to the brown or green wire it kills it. The red wire has the same volts and powers up the brown and green wire. What is my next move. ??? Thanks, Ken A.
 

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What you are experiencing is a poor connection. You have voltage but no current. The voltage falls when you put a load on it. Does the voltage fall on the fuse clips as you try to turn on the lights? The same way as it does on the headlight socket
 

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Discussion Starter #17
I can have 12 volts at the orange wire then jump
a wire to the brown wire and it goes to nothing.
I still have 12 volts when I do this at the fuse.
I also slid the housing on the switch so I could
watch the volt meter as I pulled the knob to the
half way point at the fuse box and it stayed the
same at 12.26 volts. I then pulled it on out and the head lights dropped the volts to 11.55 at the
box so it was reading right. Even though the head
light switch is not the problem I put a new one on today while it is apart. How do I increase the
current in the orange wire??? Thanks, Ken A.
 

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What do you see on the headlight switch contact, behind the plug, with the switch installed ,and everything turned on? Voltage falling there? How about if you probe into the orange wire just before it mates with the headlight switch connector. Try it with the switch pulled on. Current is falling due to a bad connection. Just trying to see where the bad connection is.
 

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Biddaddy,
You should know there is something called a voltage drop. That is when there is current flowing past resistance the voltage drop is IxR
Thats voltage = current times resistance.
However, no current and no drop.
BTW do not measure resistance when there is voltage present. anyway...
Turn on the headlight switch and THEN take your voltage measurements. You will probably find you are dropping the voltage across the fuse contacts like John said. You can bypass suspect parts of the circuit to find the trouble spot.

Turn on the running lights. Measure the voltage at multiple points relative ground (both fuse clips, orange and brown at headlight switch. If still needed jump from the upstream fuse side (hot with fuse removed) jump to (other fuse clip, then try orange at headlight switch, then try brown at headlight switch.

You can find the "open" by either measuring the voltage under load (preferred) or by bypassing the rest of the circuit.
Mark
 

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Discussion Starter #20
Tonight I started by checking voltage everywhere
and at the orange wire it was 7 to 8 volts. Last night I had 12. I read John's and chevellnut's
post from yesterday and figured a bad connection
had gotten worse. I jumped a wire from the tail light fuse to the brown wire and got lights. So
it would have to be from the fuse to switch. I
bought a 12 piece tiny file set so I could file
everything. I filed the orange wire coupling in the switch connecter and I filed the fuse holder
so long I thought I might hurt it. I put it back
together and ( I GOT FIRE ) the tail lights and dash lights work. I hope they will still be working tomorrow. It probaly was the fuse holder as John said all along and I didn't clean it good
enough. THANKS to both of you for the help. If
ya'll are ever up Dallas way stop in for some thing
cool to drink and I can lie and tell ya what an
electrical whiz I am. (HA-HA) THANKS AGAIN,Ken A.
 
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