I've been trying to resolve a P0505 code (IAC issue) and noticed that there's a plug in my engine block with a three-prong electrical connector coming out of it that's not actually connected to anything. It's on the passenger side, just forward of the oil filter and above the bracket that ties the tranny into the engine mounts. I have the Haynes manual but can't find any reference to what it is. I'm just wondering what it is and if it might having anything to do with the rough/high idle issues and the check engine light.

The engine was recently put into my van (2000 Ram Van 1500) and is from a '99 Dakota (I think). I had to replace the original engine because a piston cracked and destroyed it. I'm including a pic below. If anyone knows what it is, I'd really appreciate you sharing.

 

Block heater?

Check and see if you are getting 12 volts on two wires going to the IAC, with ignition on.

 

That is definitely a block heater connection for a 120 Volt AC cord. It can be left disconnected.

 

Okay, thanks for clearing that up about the block heater.

I'll check the voltage to the IAC. I had another IAC in an old throttle body so I cleaned it up and installed it yesterday. Light still on.

I replaced the PCV valve a couple months ago with one from Autozone but it's a real POS so I just picked up an OEM one from the dealer today, along with a new grommet, and hose. I'm going to install those and see if anything improves.

Also checked the plugs and distributor rotor yesterday and they're in pretty bad shape so I've got some replacements on the way.