1974 INSTRUMENT LIGHTS AND FUNCTION

I have a 1974 Pontiac formula firebird with a 250 Chevy engine.  I got the car in need of complete wiring.  I bought a new wiring kit and put it in.  I bought a new circuit board as well.  I am having difficulty knowing if it is working properly as I have some (what I believe to be) grounding issues.  Here is what i see:

1.  Both Blinker lights are on if I simply use the bracket that grounds the instrument cluster to the light switch.

2.  When I add an additional ground the blinker lights on the console go off and only the right turn light blinks when switched.

3.  when I use the parking brake the "fasten seat belt" light glows only when the headlight switch is in the on position.

4.  When I try to use the dimmer knob my dash lights do not dim.

5.  My instrument lights stay on all the time.

This is my current issue.  Can anyone tell me what the proper lighting is for this year car.  Knowing what should come on when will be a big help.

Thanks

Joe  

first....  check the grounds between the battery negative and the body...

second... are the individual turn signal bulbs grounded..  if you look at the wiring into the sockets at the front and back of the car.  it's usually just two wires...  the bulbs are grounded thru the 3 little tabs that hold it into the housing on most cars...
lets avoid the lack of a good ground..   cut a length of 18 gauge... strip 4 or 5 inches .. remove the bulb from the socket... wrap the bare wire around the base of the bulb in a loop and twist the bulb to tighten the loop at the base of the globe and at the top of the brass sleeve...  properly ground the other end of the wire.. this gives you a GOOD ground if you do it for at least one bulb at each corner..  enough to supply electrons to the turn signal switch circuit when you operate the switch... oh.. yea... closing the TS switch contacts allows electrons to flow in from ground to positive to complete the  circuit..    this is jUST TEMPORARY to prove the rest of the system works.


third.. i will have to study the wiring diagrams and the printed circuit diagrams to see if there are missing ground connections...  

let me post some 72 chevy images.. so you can see what ground connections are needed...





this might help you .. it should be the proper headlight switch...

 

4.  When I try to use the dimmer knob my dash lights do not dim.

5.  My instrument lights stay on all the time.



lets check the instrument lights...  

see the green wire on the diagram below...    that goes to the shortest fuse... the instrument illumination .. when you probe that fuse at either end.. you should get a variable brightness as you rotate the knob..



if you have variable brightness there.. but the cluster lights are still on full brightness.. there is a different issue..

some cars have warning bulb type dashboards... some have gauges... the pinout of the cluster connector is usually different..




 

sounds to me like you may have the wrong printed circit for your cluster or wrong hanness. you need to find a wiring diagram for a 74 with a 6 cyl to confirm the right wire locations.

why did the car need a new harness?  do you have a test light?  what kind of wiring kit did you get??

for the turn sig check to make shur all of the bulbs are good first. if it has a bad bulb the turn sig indicator will stay lit, no flash.  
76 455/4spd TRANS AM
69 GRAND PRIX 406/5SPD