I am trying to disable the Vats on xj jeep 4.0L ECM so i can use it.
The Vats as found was Enable, so i disable it and flash the ECM but NOTHING CHANGED AT ALL.
vats is disabled but the engine run for 2 second then die because the VATS.
i did made some wiring to by pass the VATS and start the engine, and it works so i know i am having VATS issue.
If I remember right..... you have to unplug the skim before writing the tune. It does work. I did my 00 XJ about 6 months ago. I can check when I get back to the office tomorrow.
FIY no skim in ecm just the vats and the car orginally without skim or vats i had another ecm with vats need that one to get the car run as i lost the orginal ecm.
Does it have a grey key or black key? Grey were SKIM Jeeps and black were only VAT.
If it has SKIM, it is mounted under the steering column, up near the steering wheel. It has an antenna ring that wraps around the ignition cylinder. If it does happen to be there you can unplug it and write your tune again. When the PCM wakes up, it should be happy. The body module still requests a key symbol on the dash as it still expects the SKIM...but it would run.
As your does not seem to have the SKIM, maybe it just needs a full write to get rid of the VATS. I am not sure. HPTuners has a lot of issues to work out on these Jeeps still. There are a number of codes and emission errors that their system shows the option for.....but don't work....like rear O2 sensors. I am hoping they will finish this up and not leave it hanging.
It has a black key without skim, the CEM from another car, same model with VATS only.
so how can i do a full write?
And by the way as you mention the O2 sensors, I have another issue with that for another XJ 2000.
the car is GCC (gulf) SPCE it had no O2 sensors at all originally, the ECM died so i replace it with one that has O2 sensors and engine light is always on giving B1S1 high voltage code and B1S2 high voltage code.
i disable all O2 sensor and write the tune, but NOTHING CHANHE STILL ENGINE LIGHT ON, SAME CODE.
Maybe HPTuners just needs somebody to read a Gulf spec Jeep and send the file to them. Over the last year they have taken on a lot wider group of vehicles and it takes time to find all of the tables and map them out. It might help them out if people in the Gulf regions could send them files... or maybe not... just hoping they will get these issues worked out.