papawhellie

Parked the xj i bought and put a new head on and was driving to install gauges. Now no spark. I put a standard products lx258 cam position sensor on as the wires had broken on the oem unit. No spark. Reading some threads here and there i back probed the ignition coil connector. I actual did put 12v on each of those. I am wondering if that could have messed up the pcm. I do have 5 volts reference at the throttle sensor, not sure about other places. I installed a new crown cam sensor and omix crank sensor. Still no spark. The ignition coil is out of spec but it was running when parked and with no pulse to it i am not thinking its a factor. Somebody help me with a troubleshooting plan.
Can a bad sensor cause the reference voltage to go away, suchvas the tps or map?

BlueRidgeMark

Welcome to the forum.

Rule #1 with these creatures, no aftermarket sensors. Stories of them being bad out of the box, or bad within weeks or days or minute, abound. Bite the bullet, pay the dealer. Use only NGK/NTK sensors, especially on the cam or crank sensors.



Not sure what you are saying here. You applied 12v to the ignition coil connector? I doubt that caused a problem. First of all, one side should be 12v, so no problem there. Second, the other side is ground, but it's only connected to ground when the PCM tells it to, so I don't think this is your problem.



Absolutely yes. If you lose the crank or the cam sensor, you'll have no spark. TPS, or MAP? I don't think so.

Your ASD relay is another place to check. Search here for some threads on it.