I posted a thread a few days ago. 1997 f350 7.3 diesel. I bought a scanner and pulled a code po221. TPS sens/sw b ckt rng/perform. Any help in figuring out what that means would be greatly appreciated. Sorry for the ignorance.

 

Sounds just like what it says. Does your scanner also read real-time data? Can you set it to read the go-pedal position and/or idle switch? If so, check both of them. Pedal position should sweep smoothly upward in percentage as you press the pedal. You can even test this with the key in RUN but the engine off.

 

I'm not real good with the electrical part of these trucks yet but I'd try and unplug the connectors at the throttle pedal and clean them with a good electrical contact cleaner.

 

Where is the TPS sensor? Are the connectors to the throttle pedal at the pedal itself inside the cab. I am not familiar with the scanner yet. But it is supposed to take live readings.

 

Does this require to replace the entire TPS.

 

I pulled the connectors off of the pedal inside the cab. The contacts look really clean. Would they be visibly damaged?

 

My problem with understanding the code is that there are other TPS codes with differing suffixs than /sw b ckt rng/perform. What does that part mean? Or does it even matter you think if I just replace the entire TPS?

 

I'll decode as best I can:
/sw == switch. Just means "sensor/switch", so the code may also refer to the idle switch, which is also on the pedal.
ckt == circuit
rng/perform == range/performance. Usually means it's not getting a "sane" reading from the sensor.

Generally, and this refers to all vehicles, the sensor/part referenced in a code does NOT necessarily refer to the part at fault. And it does NOT mean "replace that part". In some cases, it could be one faulty part creating a condition that's reported by another part. Not the case here; most likely it is the position sensor on the pedal. It could also be the connection.

Remember, our trucks are totally drive-by-wire. There's no "throttle"; the sensor is indeed the one on the pedal, it's just a "volume control" for the PCM. There's also a switch that closes just as you start pushing on the pedal, called the idle validation switch (IVS). See if you can get the scanner to show the TPS reading, either as a percentage or a voltage. The scanner might call it something like "Accelerator Pedal position" or just "pedal position". As a voltage, it should range from near zero to about 4V. As you press the pedal, the number should go up steadily and smoothly without hesitating. And the IVS should change from 0 to 1 just as you start to move the pedal. With the engine off, you should actually hear the click of the IVS. I just got an AutoEnginuity yesterday (works with a PC/laptop), and you can actually graph the data over time. So I hooked it up, turned the key to RUN (engine off), set it to graph accelerator pedal position, slowly pressed the pedal to the floor, and could see the graph notch upward from near zero to 4V. If I had seen it spike, or drop precipitously, or fail to show anything at some point during the movement of the pedal, that would indicate a bad spot in the sensor. Think of an old-school stereo, where you sometimes get a crackly spot on the volume control.

So if you get an erratic reading, and you've cleaned the connector contacts, then you'll have to replace the sensor. The only replacement I know of is a Dorman product, which I've read mixed reviews about. The Ford dealer doesn't supply just the switch; you have to buy the whole pedal assembly, um, not cheap. Another option would be a junkyard pedal assembly, or find one someone's selling on one of the truck forums.

 

Thank you very much man. That is the best description that I have found yet, and I have been looking. I can't get the scanner to graph the accelerator pedal sensor. But from what I can tell your saying is that I could potentially use an omhs meter. Could you elaborate on how to please? I actually found the pedal assembely for $65 at an local autopart store. Napa was selling them for $400. The guy at the store said that it was the entire pedal assembely. How would you suggest to clean the contacts? Thanks for all the help, I appreciate it. Oh you don't think it is the TPS that is attached to the intake manifold do you?

 

Test the TPS :You need to put a voltmeter across the GY/W and the GY/R wires on the connector to the TPS. With the key on, watch the voltage across the range of the throttle to see if there is any flat spots. You should see no less than .37 volts at idle position and no more than 4.5 volts at full throttle. The the third wire, (BRN/W), is the ref. voltage and should be 5 volts all the time.You should see smooth operation through out ...

Some times the TPS can be cleaned with contact cleaner & compressed air ...

 

As said, since direct injection diesel engines have no throttle, the only sensor is the one on the pedal.

 

Is your truck an auto or a stick ?..

 

danimalmanimal, I've been watching you struggle with this and I feel for ya! What scanner did you get?