99 TJ shutting down

[Lala23]

I have a 99 sport 4.0 that started randomly shutting down, both while idling and driving at speed. Get no codes. It seems to be related to ASD relay. I replaced relay and had no problems for 4 months. Have done this twice but this time it is not fixing the issue. Something is causing the ASD to fail?? I'm at a loss now. Has anyone experienced this delightful defect? Thanks.

 

[Kraken72]

Start checking the wiring from the pdc to the wiring under the hood. Especially behind the valve cover. I have another electrical issue and that is what I have been doing. Looking for worn or broken wiring, grounds or sensor wiring and connectors. Get the FSM for the 99 available here and start reading. Good luck.

 

[AndyG]

I have a 99 sport 4.0 that started randomly shutting down, both while idling and driving at speed. Get no codes. It seems to be related to ASD relay. I replaced relay and had no problems for 4 months. Have done this twice but this time it is not fixing the issue. Something is causing the ASD to fail?? I'm at a loss now. Has anyone experienced this delightful defect? Thanks.

Note the post below-harness rubbing the stud behind the valve cover was an issue on earlier Tjs - if nothing obvious, disconnect the battery and pull the power distribution box and start tracing those ASD relay wires if all looks good under the box -

Keep us posted - helps us learn too.