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Old 01-24-2009, 07:45 PM
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66 Mustang won't start, no lights, no instruments, batt good...

Hi guys.

I have a 66 Mustang that I've been driving for quite some timen now, but all of a sudden will not start. The lights won't turn on, the heater blower doesn't work and the instrument panel doesn't light up when the key is turned to the "On" position. Essentially, nothing electrical works.

I've removed the battery and had it tested. It reads 12.6+ V. I get the same voltage at the battery side of the starter solenoid, but it won't start and jumpering the 'S' terminal and the battery post doesn't work. I checked the alternator and I get 12 volts. I checked the hot side of the voltage regulator and I get 12 volts.

I'm at a loss here. What could cause the car to not start, as well as no lights or anything electrical? I feel like I've checked all of the obvious things, but what could I be missing?

At the very least, I've just assumed that the light switch on the car is just about directly wired to the battery so that lights can be used whether the car is running or not, but they won't come on.

This is a 1966 Ford Mustang, 3 speed automatic with a 289 and an aftermarket HEI distributor.

Any thoughts?



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Old 01-24-2009, 08:26 PM
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First off check all of the grounds, battery to engine, and engine to body grounds. Then check your battery positive connection.

If either battery cable terminal is one of the "temporary" cable end, junk that cable, and buy a ready made cable. You know, the universal battery cable end with 2 small bolts, and a metal strap to clamp the cable to the battery cable clamp. These are also referred to as 'emergency' battery cable ends.

Over time, the corrosion eats at the battery cable wire, and wick's down inside of the cable sight unseen. This in turn causes high resistance, and a loss of voltage, and cranking amps. Eventually nothing works.

Next check all of your fuses, and make sure you have battery voltage into, and out of the fuse box. If not look for a 'bad' connection in the through firewall connector.

Another suspect can easily be the ignition switch it'self, but highly unlikely since you lost the headlights, and..............................else.

Hope this helps.

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Old 01-25-2009, 07:38 AM
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also check the fuseable links coming off the solenoid, the links send power to your fuse box , ignition switch , and lights . and also check everything that carsavvycook said too do.
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Old 01-25-2009, 08:52 AM
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(truly one of the dumbest things Ford ever did!!!!)

the main power feed for the lights and power into the car runs from the alt and solonoid with the regulator wires down thru the bottem radiator support (loose with only now 40 year old electric tape wrap!!!)

pull the harness plug next to the hood hinge and check for power on the black/yellow stripe male (main power into the car)...

run a batt jumper to black/yellow female at the plug and betcha' the guages turn on with ign on...

LOL, when you pull that harness,,,it will be so totally shot,,,you will be amazed for how the hell did it run at all!!!

move the regulator over next to the alt,,,only need the idiot light wire going into the car...
(my only guess for why it is on the rad support is to gain a tiny bit of voltage drop with long wires to fool the alt into charging a tiny bit higher)
run the main power feeds along the inside top of the rad support where they belong....
rolled up fine grit (800?) sandpaper clean the plug females and grey scotchbrite the males on both of the firewall plugs for less voltage drop...

66' didn't have fuseable links but someone may have added them???

here a link to EXCELLENT correct wiring diagrams for your whole car...


Last edited by red65mustang; 01-25-2009 at 09:09 AM.
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