OldRide Answers Home
Using OldRide Answers
Ask a Question
Browse Questions In:
Other Makes
Classic Trucks
 General Topics
General Questions
Help Identify
Classic Car News
General Restoration
Vehicle Maintenance
Site Suggestions & Comments


Ask a Question in OldRide Answers
Help Enrich the Classic Car Community
Explore Closed Questions and Answers
 Search Questions: 
how start up mustang 66. ignition switch replaced.
Hi. My 66 Mustang starts up but it does not stay on when i release the ignition switch from On position.
i replaced the relay, i also replaced the ignition switch.
Please let me know if you have some ideas.
thanks and appreciated in advance.Pedro
posted: February 24, 2016
   Question is Closed   
What is OldRide Answers?
  Answers (3)
Selected as Best Answer
With ignition switch in "Start' position 12V delivered to coil via relay. When switch released, reverts to "On", Coil gets less than 12V (To decrease burning points) from switch. Look for broken or disconnected resister. Should be wire with different insulation from others, or ceramic "Ballist Resister on firewall, altho former on your ford.
posted:  March 1, 2016
Click to close this picture
Early Mustangs had a voltage dropping resistor (coiled wire type) that was bypassed when in the start position and in series with the coil power wire in the ignition switch run position. If the resistor burned out it simply interrupted the voltage to the ignition coil when released to the run position. I think it was mounted on the firewall in plain sight but that could vary from year to year. Hope that's the problem, it's an easy fix., Les
posted:  March 1, 2016
Click to close this picture
Selected as Best Answer
The "wire" or "resistor" the other answers refer to is typically a pink resistance wire. It should be in a cloth, or woven loom routed with, but separate from, the under dash wiring harness. There will be a short, 4"-6" tail off the ignition switch with a female end that this pink wire plugs into.
Sometimes these resistor wires run directly into the firewall plugs and sometimes they plug into another pigtail at the firewall.
You can use an ohmmeter to check for continuity before replacing to wire, just to confirm it is the culprit. If it is bad, replace it with the proper wire and route it the way the factory did.
As stated above, bypassing this wire will cause premature point's failure.
Be sure to disconnect the battery before attempting this repair. Removing the instrument cluster makes the job a bunch easier.

It isn't uncommon to see these resistor wires fail in the older Fords
sources: Ford factory wiring diagrams
posted:  March 1, 2016
Click to close this picture