Idle issues

I had been having idle issues. While driving on the highway it would randomly buck as if fuel cuts off then back on then go back to normal. It would randomly idle strange and shut off at lights and that seemed to have been fixed after i replaced the IAC. I also got around to fixing my check engine light and finally got it to work. It was off but i was able to pull 2 codes from it. Mark came by and scanned my jeep and he said that my TPS was bad so I replaced it and the IAC at the same time.

Code 35 Cooling fan relay. Check relay and circuit.
Code 36 Air switch solenoid circuit. Air switch solenoid circuit (non-turbo) or the waste gate solenoid on turbocharged models

I drove it to work a few days after replacing the IAC and it did great. I then drove it to big bear, wheeled it and drove home with 0 issues. Yesterday I was on the hwy and I went to pass another vehicle and as soon as my xj downshifted the check engine light turned on and it went back to having the same problems. I get to my destination, turn it off and back on and the check engine light is still there. I go to drive home maybe 20 mins later and its still acting up. I stop at a gas station and when i drove home the light was off and it drove great.

ive been dealing with kinda the same thing. im experiencing power loss, while driving & rough idle randomly.

i did, however, leave my gas cap at the gas stn. (I know that can trigger cels and such; but dont know if it can lead to the other probs).

help indeed LOL

Code 35 i'm assuming is associated with the electric fan. If so I hooked it up to a switch since it wouldn't turn on automatically. Any idea where the relay is for the electric fan? I checked in the relay box and i only see a fuse labeled aux fan and it is good.

Also I have no idea what the air switch solenoid circuit is or where to find it.

Has anyone experienced something similar?

I have not heard of it on jeeps, but yes a bad gas cap can cause those problems. My Mothers dodge stratus is very sensitive to the gas cap. Took me awhile to figure that one out. New gas cap and her problems went away. It did throw a code but I don't remember what it was.

Thanks i'll look into the gas cap.


Can anyone tell me where the aux fan relay is and where the air switch solenoid circuit is?

I cleaned all electrical connectors with CNC Electrical cleaner and then lubed with Dialectric grease. It is running so much smoother and so far haven't had any of the same symptoms.

I also installed 703 injectors and cleaned the fuel rail. The old injectors and rail were gunky and full of all sorts of nasty crap.

I still can't find anything in regards to code 35 and 36. The check engine light isn't on but when i pulled the codes last week it gave me those 2. Why would it throw these codes if the check engine light is off?

code 35 is because your radiator fan is bypassed and on a switch, I don't know why you are getting idle valve codes though.

Its not bypassed. I tapped into it and also ran it to a switch since it never turned on on its own. Any idea where the relay for the aux fan is so that i can replace it and get that working on its own?

And apparently my aux fan now works. I left it running and got out to open the gate and i heard the electric fan turn on. I then popped the hood and verified. It is working normally.