1999 Explorer XLT with 4.0 V6 SOHC will not crank. Vehicle was dead a week ago; jumping wouldn't start it. Replaced starter, started fine. The day after I replaced starter, wouldn't crank again. Jumped it with my BMW, no crank. Then jumped it with work pickup truck, started up. Started OK all day long. Today, dead in the morning again. Jumped it with both vehicles, no crank. Had the battery tested twice, it is good. Electrical test at shop stated that starter, alternator and battery are all good. Cleaned up battery posts and connections until everything is shiny. Any ideas? I've read that the chip in the ignition key couldcause this, or could the relay for the starter in the fuse box be bad? Any ideas would be greatly appreciated.

 

Could possibly be the trans range sensor (try it in neutral?) or the starter relay in the battery junction box.. If PATS, the panel lamp should prove out in about 3 seconds when the key is turn On..

 

Tried moving the gear selector to neutral, no result. The red 'Theft' light goes out after about 3 to 4 seconds when the ignition key is turned on. So that would indicate the chip in the key is OK? I guess I will try replacing the starter relay in thebattery junction box next. Thanks for the reply!

 

Swapped out the starter relay in engine compartment with the blower moter relay (same part), and both are functioning. Guy at local parts store said it sounds like I am describing a faulty ignition switch problem. Any thoughts on this one? I probably would need to obtain this from the dealer?