My 2001 Cherokee has not started since December of 2013. I got the "No Bus" indication on the odometer screen, and I replaced the CPS or crankshaft position sensor. I purchased the CPS from the Jeep dealer, so I know it's a quality part. I replaced it, connected it, and cranked it.
Still "No Bus", still crank, still no start.
I purchased a remanufactured PCM that was programmed to my VIN. I installed it, still doesn't start, but when I cranked it, the gauges went back to normal. As soon as I turn the key to "run" the next time, "No Bus" until I crank it.
The starter went out and I had to replace it. The Cherokee cranks now, but it still doesn't start.
I checked for spark, there is spark. I checked for fuel, I don't have a gauge, but fuel sprayed out of the fuel rail test port when I opened it. When I turn the key to run, the fuel pump tries to prime and then start over and re-prime over and over again and doesn't stop. I put some HEET water remover and added more gas to mix it up, still no difference.
I'm not familiar on how one would check for spark with a coil rail system. How did you determine you have spark?
Are you saying the fuel pump keeps running with the key to RUN?
The two relays in the PDC (power distribution center) that are for the ASD and Cooling Fan buzz continuously. I bought two new relays today and installed them with the same problem. The EVAP purge solenoid is constantly pulsing.
Does the EVAP Purge Solenoid keep pulsing with the key to OFF or when the key is to RUN?
I checked that the instrument cluster is tight, and it is. I've seen that a loose instrument cluster can cause a No Bus issue.
I don't know what to do. I replace so many parts on this Cherokee and more things end up falling apart. This is The Last Straw.
If anybody can help me, I would appreciate it. I would really like to get this Cherokee running, and it needs to get inspected in April.
Has your Jeep ever been in deep water to the point the water has come up to the dash or covered the footwells, or have you power washed the engine bay?
The system faults (relays buzzing/solenoid pulsing, etc., may be attributed to a corrosion problem in the Junction Block, which is the hub of most, if not all, Start-Run bus controlled circuits. The ASD relay, Cooling Fan relay, fuel Pump relay, control coil circuits are all powered from Start-Run bus A21, which is powered when the key is turned to RUN. The EVAP Purge solenoid is also powered from the Start-Run bus (fuse 10 in the JB).
NO BUS can be caused by CCD Bus problems or poor ground connections in the engine bay. In that you get "when I cranked it, the gauges went back to normal. As soon as I turn the key to "run" the next time, "No Bus" until I crank it", it could be poor ground connections.
Generally, whenever XJ's have odd problems like yours it's a good idea to (disassemble) closely examine and clean the two primary grounds in the engine bay just to eliminate them from the equation, then if you still have no joy, move on to other troubleshooting.
Here's pics of the grounds:
G100. The main battery to chassis ground.
G101. The main ground for the PCM, TCM, and O2S heaters. Obviously you won't have a coil at this spot but the ground studs are there.
An alternate chassis to battery ground path is through the radio interence suppression bonding strap on the firewall. It's woth checking/cleaning.
Check/clean these grounds and get back with your results.