Hello,
I have a 1998 JGC Laredo with 98k 4.0L 6cyl. 6 months ago I had the fuel pump module, fuel tank and cat. converter replaced. Got a new battery put in 4 weeks ago and ever since the RPM gauge goes to 0 while driving on the freeway or even in idle. The engine shuts off but can be restarted, this is getting worse and worse as it is harder to turn over and the check engine comes on and then goes off and then goes on. Any suggestions on what is going on? Thank you in advance.
-Cailin-

sounds like a bad CPS (Crankshaft Position Sensor) but 1st - get the codes stored in the computer....

Turn the key ON, OFF, ON, OFF, ON - leave ON this time, the CHECK ENGINE light will come on then go off shortly. Then start to flash the codes, count the numbder of flashes, each code will be in double digit form with a short pause between digits and a long pause between codes.

example: | = 1 CHECK ENGINE light flash
| pause | | = 12,
pause pause pause pause pause
| | | | | pause | | | | | = 55,

Code 12 - Power to PCM was lost within the last 50 ignition cycles, Battery was disconnected.

Code 55 - End Of fault codes.


NOTE: ON models with Digital Odometer the codes will be displayed on the DIGITAL ODOMETER ( code P****)

example: P0300
P0300 - Multiple Cylinder missfire.

Hello,
I have a 1998 JGC Laredo with 98k 4.0L 6cyl. 6 months ago I had the fuel pump module, fuel tank and cat. converter replaced. Got a new battery put in 4 weeks ago and ever since the RPM gauge goes to 0 while driving on the freeway or even in idle. The engine shuts off but can be restarted, this is getting worse and worse as it is harder to turn over and the check engine comes on and then goes off and then goes on. Any suggestions on what is going on? Thank you in advance.
-Cailin-

Thanks, do you know how much it would cost to repair?

I have no clue on the repair cost, the CPS is around $70. Did you extract the codes (like I mentioned above - this will help to tell exactly what the problem is).

I have no clue on the repair cost, the CPS is around $70. Did you extract the codes (like I mentioned above - this will help to tell exactly what the problem is).

No, I haven't got the codes checked but I did take it to get looked at when the problem started and the check engine light came on. The computer scan on 2-1-05 stated P0320 and P1391 with loss of crankshaft position signal, cleared codes and could not duplicate with the check engine light off. So without being able to duplicate I picked up my Jeep 2 days with no repair done and just paid for maintenance. Will it eventually just stop and not turn on or will I be able to start it up everytime it shuts off? Thanks.

well I haven't heard of a CPS going soo bad that it will not start at all, but after time the CPS will not respond right away on cold starts and you will have to leave the key in the ON position for a minute or 2 before the PCM gets a response from the CPS and allow the engine to start.

Believe it when the CPS goes bad it can do a NO Start had it happen on different Vechiles.

I Have A 94' Jgc It Also Did The Samething It'll Stall At Anytime And Can Be Restarted. But Trust Me That Won't Last For Long It Soon Won't Start At All. It Became My Crankshaft Postion Sensor, Pretty Easy To Change. It's On The Driver Side Of The Trans. The Part Is Around $50-70 Depending Where You Buy It. Good Luck.