HELP! P1504

Reply Subscribe

Thread Tools

Search this Thread

Oct 10, 2010 | 09:21 PM

broncomutt

Thread Starter

New User

Joined: Oct 2007

Posts: 11

Likes: 0

HELP! P1504

I was driving my F-450 today and after driving for 240 miles I pulled into a parking lot and the engine just died. I started it right up and teh service engine light came on and it will no longer idle. It runs just fine except it wont idle. I checked the codes and it read the p1504. which is the Idle Air Control Malfunction. So I bought a new iac and installed it and cleared the code and no change.

I checked the hoses that connect to the valve and they all look good
Is there anything else that would cause the code and rough idle.

2001 Ford F-450 V10 manual trans

Thanks for any info

Oct 10, 2010 | 09:42 PM

Mr-Pipeline

Senior User

Joined: Dec 2008

Posts: 439

Likes: 4

From: Lubbock, Texas

You might try disconnecting the battery for 15 minutes. This will reset the commuter, reconnect and try it again.

Oct 11, 2010 | 11:14 AM

crazyone77

Freshman User

Joined: Sep 2010

Posts: 30

Likes: 0

P1504 is IAC circuit malfunction, IAC is idle air control valve. One of two things is wrong (assuming wiring is fine). Iac is bad, or iac is gummed up. You can try cleaning it, reinstall, and disconnect battery for 15.

Oct 11, 2010 | 12:05 PM

broncomutt

Thread Starter

New User

Joined: Oct 2007

Posts: 11

Likes: 0

I would think the new one I installed would not be gummed up. What are the odds I got one that was bad? Would there be a difference from disconnecting the battery and clearing the code with my reader?

Oct 11, 2010 | 08:48 PM

crazyone77

Freshman User

Joined: Sep 2010

Posts: 30

Likes: 0

What kinda of scanner? Just a cheapy? IAC is pretty easy to troublshoot. If you have a multimeter you can see what the voltage is going to it. One wire should show 11-12.5 volts (battery voltage) with key on engine off. the other one comes from the EEC that commands it open depending on duty cycle commanded. you can check between ground and that pin and should see some DC voltage, unfortunatly you really need a scope to view the output right.

Start with checking the voltage.

B