Ignition system on van,Olds 1999 3.6l 6cyl,which is most likely to go bad first?

Use your original ignition and shroud so it will recognize key fad sensor.

Turn the headlights on and watch them while the key is turned to start. If the lights go out, one of your cables or connections at battery or starter is not good. If lights dim a lot but stay on, possibly a bad starter, it needs testing. If lights aren't affected by cranking position, turn lights off, pull the small wire off the starter solenoid, hook up a test light to ground and to the solenoid wire. Light should come on when key is held in crank. If it does, likely a bad starter solenoid. If no light, then the start circuit from ignition switch to starter solenoid is not working. Check for power out of ignition switch on the start wire with key in crank, to begin with. If powered, switch is good, need to check if neutral safety switch is good, and then check or swap in a new starter relay.
Post back with any results.
Good luck.

Yes, If you have a volt meter, jump and start engine, with engine running you should have approx 13.5 to 14.2volts that would tell me that batt is getting charged when engine is running. you said new batt would not hold a charge, I would be thinking about a parasitic draw(small amount of power) that in time will drain batt. things to look for are glove box lights, under hood lights that dont turn off. one easy way too see if you have a draw is to disconnect one batt cable, now use a regular (12volt non-self powered) test light and touch one end to batt cable and the other to empty batt terminal, with no light switches on and doors closed, this test light should not light and if it does then you have a drain on batt that will kill it say overnight.

Check to see if the radiator fan is coming on when the van gets hot.If it does not then on a 2.6 liter engine.look on the bottom part of the radiator on drivers side for a fan switch that could be bad and not letting the radiator fan to come on. On a 3.0 liter engine the coolant temperature sensor is screwed into the thermostat housing. And on a 3.3 liter and on a 3.8 liter engine the coolant temperature sensor is screwed into the front cylinder head. Anyone of these can cause the van to run hot and eventually die with no restart until the temperature has cooled down. Check the fan first with two jumper wires from the positive/negative post to the fan connector on a 2.6 liter engine (positive wire to open pin on plug,negative wire to insulated plug side. On all v6 engines hook jumper wires to motor. To the left side will be positive and negative to the right. Do not let both wires touch together while testing. If motor does not respond to direct wiring then replace it. Another thing to look at is the catalytic converter on van. Check the exhaust flow when the van is running cold and again when it gets hot. If the flow starts to slow down when the van gets hot then remove the converter(plugging up). After doing that run the van again to see if the van runs ok. Hope this will help you.

CHECK THE INSTRUMENT CLUSTER FOR POWER TO GAUGES TO SEE IF THEY WORK WHILE IGNITION IS IN THE ON POSITION.IF NO CHECK THE 40 AMP IGNITION FUSE.IF FUSE GOOD IGNITION SWITCH IS BAD OR HAS A LOOSE OR BROKEN WIRE.IF FUSE GOOD ALL GAUGES IS WORKING.I BE LOOKING AT STARTER AND STARTER SOLENOID.REMOVE THEM HAVE AUTO ZONE TEST STARTER.OR YOU CAN GET A REMOTE STARTER SWITCH AND SET OF BATTERY CABLES.HOOK BATTERY CABLES TO A BATTERY.WITH STARTER OUT OF CAR TAKE BATTERY CABLES HOOK NEGATIVE BATTERY TO STARTER BODY FOR GOOD GROUND.TAKE POSITIVE BATTERY CABLE HOOK TO STARTER POSITIVE TERMINAL WHERE POSITIVE BATTERY CABLE GOES.THEN HOOK THE REMOTE SWITCH RED WIRE TO STARTER POSITIVE TERMINAL AND THE OTHER REMOTE SWITCH WIRE TO THE S OR SWITCH TERMINAL ON STARTER SOLENOID.PRESS THE REMOTE SWITCH IS STARTER RUNS GOOD WITH NO FUNNY NOISES ITS GOOD IF STARTER DONT RUN THE STARTER SOLENOID OR STARTER IS BAD. THE PROBLEMS IN YOUR CAR COULD BE A BAD KEY TRY ANOTHER KEY YOUR CAR HAS THE THEFT DETERRENT MODULE SYSTEM BEST TO HAVE CAR SCAN TO CHECK THE THEFT SECURITY MODULE AND THE TRANSMISSION NEUTRAL SAFETY SWITCH IF ITS BAD STARTER WONT WORK.ALSO CHECK THE THEFT DETERRENT MODULE RELAY. BEFORE REMOVING BATTERY CABLES TURN OFF RADIO SO YOU WONT LOSE YOUR RADIO PLAYING CODE.

it sounds like the small arm inside the steering colunm has broken. on my windstar it was actually two pieces. if you do not have tilt steering the job to replace it isn't too bad tho you have to pull the steering wheel and remove the lock cylinder. to test if this is correct you would need to pull the ignition switch... it's under the steering column. there is a pin on it that fits into the arms that come down from the ignition switch. remove the ignition switch and turn the key while looking up into the hole where the small arm is. if it doesn't move it is broken.

for the immediate problem just either pull the fuse for ignition or remove the breather snorkel that attaches to the throttle body and block it off with your hand.

ignition module or pick -up coil inside the dist. is bad , video on youtube for testing . What size engine . Go to this web site ,click on ford ,pick the engine that yours has ,find ignition system testing . 1992 1994 2 3L Ford Ranger Ignition System Wiring Diagram

Do not replace the lock!
replace the ignition switch
the switch activates the starter then springs back keeping the engine running but, disconnecting the starter
repair the horn short circuit after this

They could be either way in 95. Look at the fittings where you charge the A/C. if they are threaded on the outside it is a R-12 system. If they are round and not threaded then it is a 134-A system. Good Luck

check there should be a fuse box under the hood are some small little black are green boxes under the hood one of them is your fuel pump relay.