Driving home this morning the 1984 D100 2wd 318 auto, Died, shut right down, no power to radio, lights etc,

will crank over,

Changed ballast resister along side the road, still nothing?

ECU?

Thank you

that the lights/radio also died tells you that the ign ain't being fed (starter/cranking circuit is still intact). start at the bulkhead checking for the open & work upstream or downstream from there starting with the blue wire (ign1) circuit. Grab your meter

Check the harness connector at the column from the ignition switch too. Seen quite a few that were melted.

Can't find anything corroded or melted.

Changed ICU module, still nothing.

Could this ne the pickup in the coil?

If you aren't getting fire from the ignition to the radio etc. It has nothing to do with the engine control parts. It's the ignition switch on to the interior wiring. Quit throwing parts at it and trace the power through the system.

ok, I will start over with that tomorrow..

look at ignition switch 1/2 round connector under column. j2-12bl wire powers up switch and acc. it is #4 wire in bulk head connector. it is powered by a fuse link. if power there at column, probably ign switch. if column is tilt, look at same wire but i suspect ign switch burnt out. switch is not cheap.

pulled harness apart that goes to ignition switch, I have power on the first 5 pins, including the blue number 4 pin.

Put ignition switch in from different truck still nothing.

I have power to the coil when the key is on.

nothing is burnt or melted.

1/2 round connector has 7 wires in it. wire 1 is 12 ga dark blue----wire 2 is a double wire 18 ga dark blue w/tracer---- wire 3 is 14 ga pink w/tracer---- wire 4 is 14 ga red----wire 5 is 14 ga light blue----wire 6 is 14 ga orange----wire 7 is 14 ga light blue. wire 1 goes thru bulkhead cavity #4 to fusible link. wire 2,double blue w/tracer, goes to park brake switch and then forward to cavity 14 in bulkhead and goes to 6 way under hood that goes along frame to rear of truck. wire 3, 14 ga pink w/tracer, is cavity 13 in bulkhead and also goes to fuse link. wire 4, 14 ga red,tees off to fuse box and cavity 2 in bulkhead and goes to voltage reg. wire 5,14 ga light blue, tees off to fuse box and wind shield switch. wire 6,14 ga orange,cavity 28 in bulkhead and goes to starter relay. wire 7,14 ga light blue w/tracer goes to fuse box. good luck.

check the connections at the back of the ammeter , Paul

while checking for power, I discovered that if either door is open, and I touch my tested to the radiator support, hood, fenders etc, It lights up, I have power in the body? If I shut the doors, or just push the door switch in, light goes out and no power...


I checked all 7 pins on half round connector, all have power.

make a jumper cable and go from battery neg to frame and another one from core support to battery. sounds like ground is gone. iirc, the little wire from the neg bat cable to core support is ground for lights and other stuff. try it and c what happens.

I forgot my number one rule when doing electric work, Look and see what the last owner did,

Sure enough, Taped up wire going to a fusable link, touched it and wire broke off.

also ground cable from negative on battery to rad support guy had house wire on it and It broke off.

At least I learned a lot about the electronics on my truck..

Thanks to everyone who offered help.

So, did that solve the problem?

up and running