Was wondering if anybody could help me out. I have a 2001 Grand Cherokee that started running bad and was giving code P0108 (map sensor). I changed the map sensor and it did not make a difference. I tested the wires coming from the map sensor and they have the correct voltage. I was wondering if it could be the ECM? I am going out to the garage and trace the wires back and test them before they go into the ECM. I was just wondering if anyone else had expericened this?

 

Look for a cracked or broken vacuum hose to the MAP sensor.

 

It runs bad with #16 fuse in but without it it runs fine. That fuse controls the hydraulic fan so when I take it out the fan won't kick on.
I took the fuse out and just supplied power to the fan and it started running bad again.
I was thinking it is a bad ECM?
Thanks for any help.

 

Check the charging system, the fans may be drawing more than the charging system can supply and causing the voltage to the ignition system to be too low. Just tossing out ideas.

 

When you replaced the sensor, did you disconnect the positive terminal to the battery? Sometimes the Computer won't recognize a new part (like that) unless you do so. When I replaced the Map sensor on my '96 XJ that's what I had to do to stop the code from showing up.

 

Had a guy stop by with his hand held reader. With the #16 fuse in, no signal from the map sensor. With the fuse pulled I get signal from the map sensor. The fuse is for the O2 sensors but also runs the hydraulic fan.
Does anyone know what would cause this?
We cleared all the codes with his hand held. We also disconnected the positive and negative cables from the battery.