Starting / electrical problem

1987 Grand Marquis.
At some times, turn the key and it starts immediately.

Other times, turn the key and hear a CLICK and all power (lights, radio, dash..) go off.

When this happens I at first would go try an wiggle battery cable ( which is tight) and power would be back on - try again.

I have realized that it isnt neccessary to wiggle the cable - sometimes by the time I open the hood the power is back on.

Obviously some realy is cutting off power for some reason, but I don't know what relay or why - and I dont know why the power comes back on, it just does ?

Any ideas ? - many thanks.

Climb underneath and look at your starter. There will be the large power cable, and there should be a small wire attached to the engagement solenoid with a male/female connector. Make sure the connection is tight and clean.

I found this out the hard way on my Ford F150 Christmas day when it did the same exact thing. Mine was loose and corroded. Took two minuts to fix it. Good luck, hope thats your problem...

have some ome try to start it as u get under the car find the starter and hit it with a hammer with some one cranking if it starts then u need a new starter due to stuck silinoid