P0221, 02 F250 7.3

[BLittle500]

Hey guys,

 

Truck comes in, if the MIL light is on the truck wont come off idle. Once the MIL is off the truck is fine. Only code in this thing is a P0221. Went through the PC/ED but I'm not quite clear on the PIDs they want me to check. They are looking for ETC voltage and ETC state, are the PIDs going to be APP volt and IVS (idle/off idle)? If that's the case, the PPT are telling me to clear the codes and if it comes back to put a PCM in it. Have you guys done any PCM's for pedal concerns, or should I reccomend the customer put a pedal in it first?

 

Thanks again guys,

 

Brandon

[Bruce Amacker]

Hey guys,

 

Truck comes in, if the MIL light is on the truck wont come off idle. Once the MIL is off the truck is fine. Only code in this thing is a P0221. Went through the PC/ED but I'm not quite clear on the PIDs they want me to check.

 

The right way to diag this would be to install a breakout box and verify voltages at the PCM per PCED. This also allows you to verify your PCM powers and grounds and their associated voltage drops compared to B+ and B-. The PCM has a tendency to "pick on" the AP circuit when it's pissed off about something else. (Kinda reminds me of my wife....) Check for excessive AC voltage, too, you'll usually read .02VAC at the batteries and .05VAC at the alternator hot stud idling. I'm a fucking nut about the BOB, I use it whenever I have an electrical problem. I had two 104 pin BOBs when I had the shop, we used them so much. I just have one now. It's quick to install and a real good habit to get into.

 

They are looking for ETC voltage and ETC state, are the PIDs going to be APP volt and IVS (idle/off idle)?

 

Yes.

 

If that's the case, the PPT are telling me to clear the codes and if it comes back to put a PCM in it. Have you guys done any PCM's for pedal concerns, or should I recommend the customer put a pedal in it first?

 

I'm assuming this is an intermittent problem? Can you duplicate it, and how often does it happen? I'd check the connectors and harnesses at the AP first by a visual inspection, and wiggle test with the BOB/IDS watching voltages, and verify everything works properly with the IDS. Gas guys would scope the AP looking for a rough signature or dropouts. Is this a construction truck? I've seen considerable mud in that area give grief. Most of the time it's a bad AP, but can also be a harness issue. Can you borrow an AP from another truck?

 

On rare occasion I've heard of putting in a PCM for AP problems, but it's not at the top of the list. Most of the time it's the AP itself being intermittent, but it's a good idea to go through the BOB diagnostics anyways, it should take only a few tenths. If you commit yourself to BOB diag in a situation like this, you'll occasionally find shit you'd never find any other way and you'll be glad you did. Bob is your FRIEND.

 

Thanks again guys,

 

Brandon

Check your Case Ground PID, it should read zero. If it doesn't, it means there's a bad PCM ground. I fixed a TCC problem in a Taurus a while back when I noticed the Case Ground read voltage while looking at something else. I mentioned it to the tech (who also owned the car). he cleaned the grounds, returning the CG to zero, and his TCC chuggle hot went away. Amazing what CLEAN POWER will do.......

 

 

Good Luck!