My 1997 F150 Lariat Extended cab won't start immediately. I turn the switch and my door locks cycle. I hit the switch again and hold the door lock button and it MAY start that time. I'm also noticing a pattern. I turn the key 5 times then the locks cycle. I keep turning the key and the locks now cycle at the 4th turn. then after 3 more turns the locks cycle then it FINALLY started. What is causing this? By the way it started this odd behavior shortly after I got a remote start installed a few years back but it was so intermittent I wasn't too concerned. but it got worse and I had the remote start removed and my problems didn't go away with the remote start. One more thing. Very recently I was able to hold down the unlock button and turn the switch and it would start. That went on for a few months because the dealer was dumbfounded and had no true solution.

 

The RAP module has nothing to do with the engine starting or running.

Other than doing a voodoo dance with the door switches, have you done any actual troubleshooting? The starter circuit is pretty simple.

 

Tested and jumpered the starter interrupt relay, There's a new starter/solenoid relay under the hood.

 

A 97 F150 didn't leave the factory with a "starter interrupt relay".

That's not troubleshooting, that's guessing.

 

Yes it is. Under my dash cover.

 

Heh! Must have been an option. My old 97 F150 that I drove for almost 10 years didn't have that feature.