I have a 98 Jeep tj Sahara 4.0 liter i6, The jeep died on me while driving for 3 minutes after I left my house. When I tried to start the Jeep up again No gauges were working but headlights, interior lights, stereo worked. Checked every fuse from engine bay and glove box fuses none were burnt or anything all worked. Bought a fuel pump relay as we thought that’s why the Jeep wasn’t turning over but even with the new one it didn’t run. Tried connecting my obd2 scanner with the ignition switch on but it wasn’t linking. Checked to see if fuel was in the fuel rail but it seemed that no fuel was being pumped there. Im clueless as to what’s next on checking so if anyone can give me an idea of what it is please let me know.
Jeep cranks but wont start (and gauges don't work)
- Thread starter Beartoe
- Start date
Check the automatic shutdown relay which may be sticking....
Test for voltage at the ignition coil terminals.
Thoroughly inspect the wiring harness that goes between the ECU around the back of the valve cover which is routed near a threaded head stud (right rear cover of head). This harness is known to rub through the split wire loom and wiring insulation shorting the ECU signals from the engine sensors.
Remove the plastic clam shells surrounding the steering column and inspect the ignition switch and wiring harness for signs of overheating.
Test for voltage at the ignition coil terminals.
Thoroughly inspect the wiring harness that goes between the ECU around the back of the valve cover which is routed near a threaded head stud (right rear cover of head). This harness is known to rub through the split wire loom and wiring insulation shorting the ECU signals from the engine sensors.
Remove the plastic clam shells surrounding the steering column and inspect the ignition switch and wiring harness for signs of overheating.
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PCM crashed or whatever so now I need to buy a new one. Any reliable sites I could order from ?
A no start issue with fuel and battery gauges not working and no OPDA connection (no codes) are good signs of a bad crank position sensor. These were the exact symptoms on my 01 that a new sensor fixed. Challenge will be finding a Mopar replacement. I ended up buying an NGK unit and it seems to be working fine.
To be quite honest with you I didn’t really diagnose it my self. I’m clueless as to what exactly I’m supposed to do so I had someone come down and try to diagnose it. Ran all sorts of tests and in the end he took out the ecu and started to look around for a new one (which seem to be impossible to find). The grounds on the wiring harness seems that connected seemed to not be working properly and told me that it probably shorted out? Told me I might need to replace the Ground wire that connect to the battery and have another ground cable running to the block.
Any way I could tell if it’s the sensor causing me problems before I go out and buy a new one?
How would a bad crankshaft position sensor cause the fuel and battery gauges to be inoperative? That sounds very improbable to me.
See if you can find a buddy from a local forum or something that'll let you borrow his for just a second to diagnose. There are some variations so I won't guarantee compatibility, but I think any '97-'99 pcm will work regardless of transmission. Just no SKIM (grey security key). But I doubt that's it anyways. I can't tell you how many times I've seen people blame the PCM (or bad gas 
) when it's the harness.
) when it's the harness.
https://wranglertjforum.com/threads/dash-gauges-are-dead-and-jeep-wont-start.9853/
Take a look at this thread before ordering a new PCM. My Jeep just started having issues like yours this week. I haven't had time to diagnose yet, but I found this thread while searching the forum. The CPS seems to be a likely solution for me, and maybe you too.
Take a look at this thread before ordering a new PCM. My Jeep just started having issues like yours this week. I haven't had time to diagnose yet, but I found this thread while searching the forum. The CPS seems to be a likely solution for me, and maybe you too.
I researched it on here and also a few YouTube videos. Figured for a $24 replacement off rock auto it wouldn’t hurt to try either. The NGK is made in USA too so glad it worked.
This is the exact thread I used as well. Specifically post #3 which states:
Typical Symptoms –
- Starter cranks and cranks but engine won't start up and run.
- Fuel gauge and voltage gauge may not work or display properly.
- You sometimes will have No Bus on the odometer after 30-60 seconds.
- A failed CPS/CKP may or may not throw a CEL trouble code.
- No spark at the spark plugs.
- Fuel pump should run and prime for 3-5 seconds.
Cutting to the chase... the CPS has nothing to do with the battery or fuel gauges. The CPS doesn't have to even be installed for them to work and the engine doesn't have to be running for them to work. The CPS doesn't do anything or produce any kind of a signal when the engine isn't running. They are unrelated and in unrelated circuits.
I don’t doubt you and I have no idea how it happened but these were my exact symptoms. What I also found strange was my OBD scanner would not connect to read any codes but did successfully connect after replacement. Regardless I think it’s worth replacing for the price but hold onto the factory Mopar unit just in case it’s still good.
I could believe that the wiring harness from the ECU to the sensors which is routed near the threaded head stud (right rear corner) would be the problem; since you were working around the area while replacing the CPS and more than likely moved the harness away from the stud.