Power issue through ignition switch

[Leedanger]

Hey guys...
4.3L serial # 0F587086 (1995)

I’m randomly not getting power through the key switch. I have 12v at “B” connection but when I turn ignition to “I” or on position I lose the 12v on both sides (“b” and “I”). Took the ignition switch off and it tested fine (continuity from b->i in the on position) but installed a new one anyway and same issue. If I disconnect the ignition wire I then get 12v on both sides of the switch so has to be a bad connection somewhere. Also with all wires connected key on position I get 12v on both sides of 50 amp breaker at engine. If I let it sit for a while it will all work again randomly.

 

[Bondo]

so has to be a bad connection somewhere.

Ayuh,..... Sounds like corroded connections, probably a ground,....

Start at the battery, 'n work away, both power, 'n ground wires,.....
Shiny Clean metal,.,...

 

[Aluminum magnet]

Not sure if this is the same for a 1995, but you may look at the starter solenoid. Mine had a similar issue. Turns out the ignition position drives the slave solenoid, and puts 12v hot to the coil. Solenoid failed and was drawing too much current. Again, it may be a different set up you have.

 

[Leedanger]

Ok. Thanks guys I’ll report back with results assuming I have some

 

[Bt Doctur]

Aluminum, better check your info before posting
Intermittent loss of power is usually due to a dirty/loose/corroded ground lead
Main system power comes from the starter battery lug, then to the 50A CB with the red button, from there thru the harness to the dash..The ign key gets power from the Red or Red/purple on its "B" post, the "I" post has 12v with the key in the on position and if fir the ign circuit. The "S" post is for the starters slave solenoid that only has power in the "start" position

 

[Leedanger]

Corroded ignition fuse tucked in under the dash. With the key on I just did the ol’ Jiggle the damn wires maneuver until I heard the screamer pierce my eardrum.

 

[Leedanger]

Thanks er’ body

 

[Retain29]

The 50a Fuze, big red button, should I be "unable to push the button in?" .It seems totally solid. Most fuses I have ever saw you can push the button in or their not solid.

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[Bt Doctur]

it`s an illusion,when tripped the button moves about a 1/32 of an inch. resetting it you only hear a click, the button has very little movement inward

 

[kip2001]

Corroded ignition fuse tucked in under the dash. With the key on I just did the ol’ Jiggle the damn wires maneuver until I heard the screamer pierce my eardrum.

Leedanger I'm having nearly the exact same symptoms with my wiring, "B" terminal has 12volts when key is in off position, when I switch the key to run, "B" and "I" terminals both have no voltage. Can you elaborate as to what fuse was corroded? As far as I know there should be no fuse past the "I" terminal on the purple wire.