P0505-Idle Air Control Malfunction

I replaced the Idle Air Control Valve for the 2nd time in 5 months period and had the error code resetted. Before starting the Jeep, I did that on/off procedure to check that the error code has been cleared before starting. The code P0505 came back immediately. Is this a sign of bad wiring? Do I need a voltometer/multimeter to check the wiring from the connector to the PCM? Can the PCM go bad? Thanks.

I would need to know year then from 93 to 2000 I have diagrams and can tell you color of wire and pin # on pcm. Year & eng please.

2003 Grand Cherokee Limited 4.0.

best bet buy haynes repair manual or may be someone here has book that covers your 03. Mine only goes to 2000 and the wires are diff colors with diff #s on pcm. I dont know if you tried to remove plugs from IAC sensor and or pcm then used contact cleaner. just a thought.Is there any kind of build up on IAC that would effect its function maybe .Good Luck

It's a brand new IAC. Replaced it last saturday. the error code won't stay cleared after resetting by using the code reader. I checked to make sure that the code was cleared before starting but it was not.

If the IAC motor is new and it idles fine but keeps resetting code P505, I'd say it's a wiring problem. You will need to check each wire for proper voltage, especially the signal wire, the one that feeds info back to the PCM.

It does not idle properly....it keeps stuttering like it was trying not to stall.

you may want to try taking throttle body off and remove iac then clean ports etc. It still maybe mechanical ,check and replace as need gaskets.it should be 4 wire system plug in and should be rt side fire wall. could remove connectors and use contact cleaner at pcm and iac. good luck

Is there a name for the contact cleaner? Renu?

Any brand electronic contact cleaner. I am electronic tech so I get from my distributor but I would think radio shack or even auto parts store should carry. tell them you want to clean electronic plug contacts. I use carb cleaner on throttle body

Well, the Jeep died today. The jeep does start but will not stay running after starting. We have been having a lot of rain this morning. Could it be the moisture affecting the IAC or PCM or the wirings? I dread to take the Jeep to the mechanic....

Sometimes a code will pop just because pcm trying to compensate with that particular sensor and its really something else.Did you clean the throttle body? As I see it it probably has something to do with air mix. you may want to also check fuel pressure . But if you didn't clean out throttle body or connections they still could be your problem.The thing is you need to start somewhere if those things dont help the problem they are then eliminated and probably needed cleaning anyway.One more thing you say it starts but will not stay running, If in neutral you start and you press on gas pedel it stalls? Or when you try to drive it stalls.

had similar issue with random codes setting what i did is opened the harness going through the center of the engine by the valve cover and spread all the wires apart they tend to melt and stick to each other around that area due to heat. picking up voltage or resistance from other wires

whoooo.....MORE CODES:

P 0031
P 0505
P 0135
P 0141
P 0155
P 0161
P 1294

All oxygen sensors and IAC related.

Rereading your first few posts and now this one, it makes me think veh is running lean. check all vac lines for breaks etc and I would get throttle body gaskets and still clean t body. Also sometimes a weak fuel pump or restriction in fuel line like f filter can cause lean run all above can code 02 sensors. It just seems hard to believe all 02's are bad. also intake gasket could be leaking causing lean run. vac leaks can sometimes be detected by spraying starter fluid at suspected leak areas , throttle body gasket area or intake. just be careful cause starter fluid very volatile. when spray gets sucked into leak, idle will increase proving vac leak area.

Don't forget that the code P 0505 failed to clear after resetting with a code reader. I checked before starting the Jeep.....

I did not forget maybe you have bad pcm hope not cause dealer needs to flash. I am saying all codes have to do with 02s and air control not being able to function in their respective parameters and the pcm reports that, we just have to figure out why those sensors are not able to do their job, is it cause sensor(s) are bad, pcm or just can't function because. And thats the thing because. Because is the hard part. if its a sensor you replace and all is good with the world, when its an outside factor causing sensor not to function properly it will still code thats the because, that needs to be found you can try removing plugs from pcm then back on repeat several times I would not spray and I would clip lead myself to ground (you can use metal watch band on your wrist ) so you dont throw off static.Also I am suggesting you clean all ports in throttle body replace any gaskets and look for vac leaks vac leaks will effect 02 sensors and all of yours are coding.Maybe there is leak right at throttle body. but if not and you cleaned and replaced gaskets you can eliminate that.Or you can just bring to serv dept.and pay for them to figure out. Maybe wires did fuse together as someone else had suggested,but with the codes 02s I don't think those wires run on top of motor so I don't think thats your problem. I do think its one problem causing all codes. I don't know cause its hard not being at veh. Good luck let us know how you do

oxygen wires do run over the engine the code i had was oxygen heaters replaced oxygen sensors replaced pcm an found codes resetting within one mile or sooner also checked fuses the only thing left was to open wires thats when i found wires bound together

Looks like Rizin84 has had your exact problem and he states those wires do in fact run over eng. I would run with his suggestion first. let us know its good to post back so we feel we are not wasting our time. good luck

I'd look to see if there's a specific setup for the iac. I had eaten through a few of them in a buick i had because i thought and was told that a computer reset was enough. when i found out what you had to do to get the thing to actually work there was no way i could have done it without taking it to a shop.

Here's the verdict......melted wires. Had to replace wires, Relay switch and IAC. My main concern is the PCM and the mechanic says that the PCM is ok for now but it may need to be reflashed in the future if the Jeep cannot maintain its normal idle speed. The new IAC were "shot" and the valve was all the way out.

engine light came back on. P1035, P0155 and P1294. Oxygen Sensors and not maintaining proper idle speed (IAC).

All fixed now. Mechanic replaced 2 oxygen sensors. Idling great now but there is a possibility that the Jeep may need a new computer if it is causing to idle erractically again.