Mattgmann

Thanks in advance. I've searched as hard as I know how for some insight into this.

I was having a new key made (2001 xj limited all stock 150k miles), and the tech is unable to communicate with the computer. I checked and cleaned grounds throughout the vehicle and checked all fuses. The obd port appears to be good, and skim is fine. What else can I test? Is there a way to bypass the skim so I can at least get the Jeep running?

Note: Jeep was running great (no errors/codes, no run problems). I just lost the key.

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wizardpc

If you had a grey key, you have SKIM and will need to either have a new key programmed or
1) remove the SKIM module and then
2) replace the engine computer with one from a non-SKIM'd 2001

I'd see if the tech can ask for help. You're at a Jeep dealer, right?

Mattgmann

No, not at a dealer. I'm using an independent locksmith. The trouble is that his system cannot connect to the Jeep computer to draw the codes to program the key. I'm trying to troubleshoot why there is no communication. I highly doubt the ECM died in the 24 hours between me losing the key and trying to have a new one made.

Update: I found that the ECM fuse is not receiving power. Should there be current to the ECM fuse with the key in start position? Is there current to that fuse dependent on a relay?

Thanks

Mattgmann

Update: I found my service manual. Fuse 18 and 21 receive current via the ASD relay. Neither fuse is receiving power with the relay engaged. I tested the relay and it tests good. I did a continuity test between the the relay cavity and fuse and all is well, so the issue is on the ground side. For information sake, it's circuit A999 16RD.

If anyone has been down this road, please chime in.

Thanks

Turbo X_J

Sounds like it's locked out, probably tow it to a Chrysler/Jeep dealer time.

cruiser54

This is a real longshot but a buddy of mine was a tech at a Jeep dealership and happened to mention one day that sometimes he had to unplug the CPS when the tester wouldn't communicate with the ECU.

Mattgmann

Solved. Sort of.

I burned the midnight oil reading the service manual and checking circuits. Everything was good, but still want getting power to the ECU. I realized the ASD relay was only starting on for a few seconds with the key in the on position even though the circuits and relay tested ok. So, I jumped the relay and bingo, able to communicate perfectly. I pulled a few stored codes. I suspect a temp/voltage sensor is bad and tripping the ECU to cut off the ASD relay. That, or an o2 sensor. Once the vehicle starts, it runs fine, so I'm guessing there's a voltage drop to the sensor that flags it.

I'll track down that sensor and replace the 1st bank o2 sensors and see if it takes care of those codes. Otherwise, the Jeep is back in action.

cruiser54

Thanks for the update.