Ok so I've done plenty of research but still can't seem to fix this issue...

96 jeep Cherokee 4.0 with 160xxx miles. Engine is throwing a P0443 code. So I've replaced the evap solinoid and verified that it works by using a jumper to activate it. All of my research led me to the ecu not switching the ground and needing to be replaced....

Before dropping in a new ecu I took it to a shop to verify my diagnoses, which they did.

Got a new ecu and still same code.

I'm getting 5v on the power side to the valve. I checked and have continuity on the ground cable between the valve and the ecu plug.

I am totally stumped and I need help!!!!

 

Usually P0440 is a faulty fuel filler cap. It's best to replace it with an OEM but there are aftermarket caps that can be used (but not recommended).


That is to say you are going to replace the cap.

 

I'm sorry I meant p0443 code

 

Power to the valve should be 10 volts or above.


Not sure if this applies to a '96 or not.

 

That's what I'm trying to determine. If the voltage is suppose to be 10 + at the solenoid....where is the drop

 

Between the PCM and the solenoid.

 

Doesn't the PCM only control the ground on the solenoid?

 

You're right, the PCM provides the ground driver.


I don't have 1996 XJ wiring diagrams so I can't help finding the power source for the solenoid, but I think there will be a fuse in the fuse block under the dash.


'97 + fuse is located in the junction block in the passenger footwell but that won't help you any.


If you can find the fuse pull it and check for corrosion at its pin cavities and measure the voltage going in to and out of the fuse holder.


And, measure the resistance between the fuse holder and the solenoid (battery disconnected).

 

So I was able to track the power wire to the fuse box (spot 19). I have continuity between the solenoid and the fuse box. However...I'm not getting power to the that spot on the fuse box. As far as I can tell, both wires for spot 19 run up to the dash before going to the solenoid.

Anyone know where is the dash these wires go?

 

Yes I am currently having this same problem with that fuse...pulling my hair out...any suggestions??

 

so I unplugged the sux fan relay and ac clutch relay and fixed the problem with the egr solenoid. At least I can smog it before tackling what is causing the short.