Having finally gotten the truck to run long enough to do the slow code tests without acting up, I now have codes to work with.

The three codes I got from the KOER slow test are:

12 Cannot Control RPM during self check. High RPM Check
13 Cannot Control RPM during self check. Low RPM Check
21 Engine Coolant Temperature out of range during self test.

I also noticed that when I put the scanner in datastream mode that the engine stays in open loop. I assume this is due to the engine coolant temperature maybe?

Not sure what 12 and 13 mean... from the code tables I assume it has to do with the Idle Speed Control, but not sure if I should be checking to see if sensor readings are ok, or if I am looking for a faulty part or where to start...

Any input is greatly appreciated...

Rich

 

I found information about the Idle Air Control Valve/Motor. I did the electrical check on it and it seemed ok. I removed it and checked that it moves (which it did freely). I cleaned it before putting it back on as it did have a great deal of gunk in/on it. The engine is now idling about 200 rpm faster when I first start the truck. I cleared the codes and they show up again when I run the test.

Could this be the result of a vacuum leak?

Rich

 

There was a tech bulletin about the throttle body gasket being sucked in--replace the throttle body gasket if you haven't. The engine has to be up to temp or you will get the 21 error.

 

Did you evr get this fixed?