I just picked up a 91 4.0 auto 4wd 4 door and I'm having a weird no start issue. It starts intermittently in park but Everytime in neutral, is there some type of sensor that causes this? Also having issues with my headlights not turning off unless I pull the switch in and out numerous times and even then sometimes I just have to wait for the to go off. The only reason I mention the headlight issue is because it sat for maybe as long as a year before I bought it and some mice took up residence in it and I don't want to hide the possibility that wiring has been chewed.

 

Welcome and congrats on the new rig.


I had the same issue occur on my 90XJ. There is a Neutral Safety Start switch, NSS, that is supposed to allow the vehicle to start only in N or P. The switch contacts can get dirty and then the intermittent no-start begins. You can push against the gear shift to get it to start in P but eventually that stops working too.


If the NSS is the problem, then it can be opened up and cleaned. But first, test the signals coming from it using an Ohmmeter to see if there's a problem. With vehicle in P, not running, unplug the connector and test for continuity between slots B and C.