Code 21

[southernspeed]

Truck has been running great but today started acting up at idle. Not much but the idle was fluctuating ever so slightly which is unusual for my rig. I parked up at home and just as I was about to switch off the idle climbed to around 1500 or so rpm for a couple of seconds and then went into limp homr mode, throwing an SES light.
I switched off and then restarted after looking around in the engine bay and it did exactly the same. I pulled a code 21 .

So...does this sound simply like a bad TPS or is there more to the story?

 

[dyeager535]

Pull the ECM fuse for 10 seconds, reinstall, unplug TPS, blow out connector/pins, replace, run the truck, see if it comes back.

If it comes back, going to need to see if the TPS voltage is right, and the sweep is "smooth" in voltage.

 

[southernspeed]

Thanks, I'll have a go at that one evening when this damn rain stops!

 

[dyeager535]

I haven't paid enough attention, but with the EBL, can you watch all the operations of the engine (RPM, TPS voltage, speed, etc) while it is running?

Apparently the codes are GM standard fare as well, which is nice.

Which code is 21? High or low voltage or? When you pull the plug, inspect as much of the wiring as you can.

 

[Cricket]

21 is high voltage and 22 is low voltage.