My 99 grand cherokee 4.0 threw a code for a faulty leak detection pump. I tested the leads going into the pump with a test light and got a negative result. Do these leads have a 12v constant or is power supplied to the pump only when it needs it??

 

No one has any ideas here?

 

I'm almost positive that it is NOT constant power. It cycles on and off. They are notoriously bad also and I have changed quite a few if that means anything

 

Would a loose/disconnected vaccum hose cause the code 1494?

 

The LDP needs a vacuum source from the intake, I am pretty sure if that was disconnected or clogged/restricted you would get this code.

 

Welcome to CF.
This might be helpful.

 

Thanks for all the help everyone! I found the culprit and it was a disconnected vaccum line from the pump to the manifold. Again, thanks for all the help!

 

did this cause a nasty misfire for you?

 

Not at all.