I recently bought a '98 Cherokee Sport 4.0 auto. Yesterday a check engine light came on and quickly afterwards I noticed a loss of power. Then I figured out that it wasn't down shifting from third, so whenever I accelerated from a stop, it was extremely sluggish. I tried starting in 1/2 and it wouldn't shift out of first.

I read about the TPS being a major problem with the XJ and took it to Auto Zone the next day to scan for codes. The first one was a too high voltage for the TPS along with Transmission Solenoid, Air Bag and ECU codes. I replaced the TPS with a brand new one with no change in issue.

I decided to test the voltage going into the TPS by taking my negative probe and placing it on the negative terminal on the batter and then testing each tab inside the connector from the harness with the following reading 11v 5v 5v. Obviously these are way too high, but I can't figure out why they would read so high. Could it be a bad ECU? And ideas would be helpful. Thanks.