My Jeep does not always start. All the dash lights come on, but when I turn the key to start the engine, they all go off. The lights stay off, and the engine will not start. The ignition won’t even click… it’s similar to a dead battery. When I turn the key back to its original position (when first inserting), all the gauges spike and the needles jump really high for a split second. When the door is open the gauges keep jumping (spiking). After waiting for 30 minutes, the engine will start fine like nothing was wrong (except the fluctuation in idle). It would rev high at idle sometimes, and sometimes it would idle low… so low in fact the jeep stalls.
I have read about the symptoms of crank/camshaft sensors and relay, but I wanted to make sure from people that know more than I or have faced this particular problem.
As far as the not starting, make sure the battery terminals are clean and the connections for the ground are clean and tight on the body and engine. The IAC is probably dirty as far as the idle. I would also clean the MAF with sensor cleaner. Are their any codes set. You can get the codes read at an auto parts store.
IMHO, it’s not that weird to have older Jeeps with starting problems. After taking @knfenimore good advice, I would take it to a shop. Electric problems are hard to trace without being their.
I would ignore the P1494 for now (evaporative emissions system issue). You should address it eventually, but it won’t have anything to do with your symptoms.
The P0505 is about your idle air control system which consists of an idle air control valve (IACV) mounted on your throttle body, the ports for said valve, and the wiring to control the valve. Thus knfenimore mentioned the possibility of a dirty IACV. Since the PCM is onto the issue, I’d be thinking more about a failing valve or wiring problem - but cleaning it can’t hurt.
As for the no-start, again - what knfenimore said. You start with the simplest stuff which is to check the main power cables and connections. A huge number of weird and intermittent problems like this are fixed from doing stuff as simple as that.
Who knows - you might end up cleaning and tightening a ground connection that also makes your IACV happy.
Consistent with a high resistance connection somewhere between the battery and the car’s electrical system wiring harness. (“High” meaning 0.1 ohm or more.) When you try to start it, the 100 Amp + draw to the starter motor is enough current across 0.1 ohms that the voltage in the wiring harness drops to near zero and the dash lights go out. I had this same symptom on my Corolla a couple years ago. It turned out to be one of the battery cables had worked loose. It could be something unrelated to all that, but if I had that symptom, that’s the first place I’d look.
