You people have helped me through several restorations, and I could use a little more help. I am working on a 70 wagon, that has a 75 302 installed with the later electronics- The wiring harness on this one seems pretty much intact, just some things unplugged. I am having issues with the lighting. I can not get the front turn signals to come on with the lights, but seem to have all the other lights working. When I turn the haz switch on- the front signals blink- so I am getting power. Also the fuel gauge does not work, but I find it hard to believe both senders are bad- When I use a test light at the gauge- it is getting power, but light blinks like it was connected to the turn signal (this is with all lights and turn signals off)
When I turn the signals on- the alt gauge spikes up and down????? Is their anything that jumps out at you that I might have hooked up backwards? Or should I take the diagrams and start verifying each hook up? I did notice this truck has the battery grounded to the block, but no other ground straps- block to frame/ block to body- would this cause the issues?

 

The lack of grounds could very well cause problems. The battery should ground to the block. Then from the block, a ground to the frame and to the body. Until you have these you are wasting your time chasing anything else.

 

Poor grounding is the cause of most electrical problems as stated above.

 

Do the work as park lights? First position of the headlight switch pulled out? First make sure that the bronco has the correct bulbs in the park/turn indicators. They should be 1157s I think, which have two elements. If you have bulbs that have only one element... I dont think they work properly... I think I had one like that on my truck when I bought it. I would then check out the headlight switch wiring. The reason the turn signals come on with the light is there is a lug on the headlight switch that powers them up when you pull out the headlight toggle on the dash. Pull the headlight switch out and then examine the terminals with the wiring tree removed and look for corrosion....

I also agree with the two previous posters.... make sure your battery grounds to the block and the block grounds to the frame...... bad grounds create all types of electrical gremlins that creep from one area to another.....