1999 Jeep cherokee 4.0 won’t communicate with scanner

ID Status Date Year Make Model Transmission Type A/C Controls Public/Private
#14828 Closed public

jeep will start and die or start and run for several minutes and die. engine light is on but no communication. I replaced ECM, still the same issue.Any ideas?


Try another scan tool if possible. Also check under  vehicle specific and OBD 2 listings. Other than that  I would start by checking for 5 volt reference at several sensors. Follow that up with checking powers, grounds and communications lines for proper signals.

I’m using a Snap on Solis Pro,All DLC lines check good. Communication lines ohm good from DLC to ECM. All sensors have 5 volt reference signals. The TCM is the only module that will communicate. And yes, all powers and grounds were the first thing I checked.


Forgive me. I don’t want to sound insulting but I need to clarify a few things about how you tested.

All power and ground signals have to be load tested.

Communication lines need to be isolated and load tested.  They also have to be checked to make sure they are isolated from power or ground. Once they are confirmed to be good then they have to be reconnected and rechecked with a scope or a good multimeter. This will confirm a communication signal is present.  Remember to look at your wiring diagrams and isolate modules on the same data lines so you can see if a particular module is interrupting the communication signal.

The five volt reference has to be checked with all sensors and computers connected.  The wires have to be back probed and measured.

Be sure to check in the plain OBD 2 mode on your scan tool. I have always used either OTC or Autel and many times they will not communicate with Chrysler products  except in OBD 2 mode.




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