QuestionI have the 4.0 engine. When I reach highway speed of 55 mph the engine shuts down and will not start again till I turn off the ignition and turn iy back on. Yhat leads me to believe that it is the ASD relay. however I don't understand why it always kicks at 55 mph, and runs fine at all other times. Can you help?
AnswerHi Ken,
That is an unusual behavior. Do you have a tachometer on the car and if so, will it cut out at a lower speed when you have it in the next lower gear but the same rpm or does it seem to only relate to speed?
It may be a precursor to the failure of the cam or crank sensor. You might try reading out the controller for any fault codes that could be stored in its memory. On Chyrsler products of that vintage you just turn the key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. The check engine light will remain on but then begin to flash, pause, flash, etc. Count the number of flashes before each, then repeat to verify that the count is correct. Group the numbers in pairs is the order of appearance to form the two digit fault codes. Then write back for what they mean and what to do, although I don't know that this readout technique will work on a Jeep, or that the code numbers are the same. If not, then ask other Jeep owners for the trick, because this is still an OBD-I vehicle so it should have a self-readout capability.
I don't claim expertise with Jeep, so this is how I would advise a Chrysler owner.
The ASD is probably involved, but it is dependent on the cam and crank sensors being reliably working, unless it is flakey on its own accord.
Does cruise control have any impact on whether or not this happens? That is the only system that is speed dependent that I can think of.
I'd be interested to know what you learn in any case.
Roland
