I know there are other threads on this but I am hoping you jk guys who know the computers on these may offer another reason for this one:

The other day I had to park on the street overnight at my house. As I do not have an alarm, I thought I would pull the fuel pump fuse under the hood just so I could sleep. That is when all went wrong! Pulled fuse and tried to start. Not only would jeep not start but it would not even turn over. Turn the key to the ready position and everything was OK. Turned the key to start and heard "click", lights in dash went dim, etc.

So... I put the fuse back in and tried it. Same thing. In my frustration I engaged the key to start several times and saw a "no fuse" pop up on my dash (where it shows mileage). As I had a fuse in, I checked the battery. 12.7 volts with zero load, key in ready position (int lights on 10.2 volts, key turned to start position with clicking sound 6.2volts.

Completely frustrated, I took a five minute break. Came back out and tried to start it - started and ran perfectly but has check engine light on. Disconnected battery for 10 minutes, reconnected and started again - all is good with no check eng light. Has started a half dozen times since with no issues.

Could the Jeep computer have sensed something it did not like when I pulled the fuse and tried to start it and go into a shutdown mode? Re-set itself after sometime?

Grasping at straws here. Just bought it three weeks ago. My first Jeep. Still learning about them.


Thanks

 

I'm no expert but I think you nailed it. I'd guess it did a safety shut down. Then you basically reset everything by disconnecting the battery for ten minutes. I did that when I disconnected and reconnected the airbag wiring harness when I temporarily removed my passenger seat.

 

Pulling the fuse for the pump is how you let the pressure out of the fuel system. My jeep will run a minute or more with the fuse pulled. No warnings or check engine, sure you pulled the fuel pump fuse?

 

It sounds like it could also be a faulty park sensor which is located at the shift lever and is engaged when your jeep is in park. My jeep, an 08, occasionally does the same thing. I just push the gear shift lever forward a bit and then it starts right up. Give this a try the next time so you can rule this out as one of the possible problems. This part can be replaced and is covered by the warranty if you still have one.

 

What was the problem??

 

Battery reset. Good idea. These computers can be really sensitive. My guess is it shut down in safety mode with the fuel pump fuze pulled in order to prevent a dry start.

 

Yeah, modern cars running a CANBUS system are very dependent on voltage levels. Many modern cars use voltage levels as a sort of sensor. For instance, if a brake light blows, there will be a change in voltage in the circuit that was supplying it. The computer recognizes this and then causes the turning signal light in the dash to blink super fast, indicating to the driver that the light is out. Drop the voltage from the battery, or remove something from the circuit, and you can see how it throws a wrench into the system.