I personally have a set of rhino ramps that really come in handy when going underneath the car,definetly check for any broken/frayed wires leading to the sensor,could possibly be a wiring short/fault in the sensor/solenoid,also while your under there try cleaning any harness/connector with some electronic cleaner as mentioned a while ago,overtime dirt/oil buildup forms and can cause those annoying intermitent issues,check to see if any wires are rubbing against the engine block,heat exposure can cause many unexpected issues to arise. Z