I have a 1975 f150 4X2 4BBL. with a 390..electric ignition.
my girlfriend filed the magnetic pickup because she thought it was a point system..now i got no spark...
Im thinking maybe thats why...
I have checked for power at the coil. it seems fine..
i put a test light on the neg. cable(disconnected) from the battery to the neg. terminal on the battery. supposedly because the light was on that means there is a short in my system???
I am tryin to find info on here..it is frustrating but i love this sight...
please help....no spark...
i replaced the coil and the ignition switch to no avail
...thanks

 

You are saying she took a file to the magnetic pickup? You're still trying to get it started with a sanded-down pickup?

Connect your test light from the negative terminal of the coil to clean, unpainted metal on the engine (ground). What does the light do as you crank the engine?

 

hi..thank you.
That test i have ruled inconclusive because i wasnt sure i did it right...
I did not get any light at all from neg.coil to ground on engine and turning it over...It does light up from +side to neg.battery terminal though...
finally some great weather for workin in minnesota!!!

 

The light is supposed to BLINK when performing the test I have described. Possible contributors to failure include a bad ignition module, no power to module, or bad pickup module.

If your girlfriend tore up the pickup module with a file, that's the first thing I would point to. If the truck wouldn't start after she ground it out with a file, why did you bother with the coil or ignition switch? Replace the pickup module to take it out of the equation.

 

She says she just cleaned it up.not file to much.. I can see that its been filed though...
yes...i am trying to start it.
I put new wires cap and rotor,and plugs in a few days ago...It started on the 1st crank..was running great for a minute then chugged out.
It started for a minute then back to no spark..i thought it might have started because of the new parts..after that one start, there is nothing...just like it was before i put the plugs and stuff in...
the magnetic pickup looks good still but i havent ruled it out yet...i suck at troubleshooting...
I am trying though

 

Your right...I didnt know what she had done till today...
If im right?The test...test light to neg terminal on coil to ground on engine and turn it over?if it is right then i have no light there...
So...u say that means ...
1.bad icm
2.bad magnetic pickup
3.bad coil
??
I guess the test i did to determine a short in the system does not mean the magnetic coil is good...How do i test the magnetic coil?
please help

 

The only test you can do on the pickup is to disconnect the distributor and measure the resistance between the ORANGE and PURPLE wires coming from the distributor. It should be between 400 and 700 ohms. This will only test the continuity of the inside of the pickup. It will not catch damage to it externally.

If the light does not BLINK per the test procedure, then the coil is not being switched. I did not say this means the coil is bad. I said the following:

The other test you did with the test light in between the battery and the battery cable is only for finding parasitic draws if your battery drains while the truck sits. It has nothing to do with proving out the ignition system.

 

Reading between black lead and orange or purple should be at least 70k ohms. Less means it's shorted to ground.