Expo

Since my last autocross my 85 has been throwing a code 21 and the idle goes up to 1100 until I reset the PCM by disconnecting the battery. It doesn't happen immediately and sometimes it does it at idle or others I have to drive it a few miles before the SES light goes on. Code 21 is supposed to be high power steering pressure.

I can't find a sensor or any other wiring going to the steering components so it can be looked at. My question is there a sensor and wiring going to the PCM and can it be disconnected to eliminate the code and light? Any response would be appreciated..Expo

C4boy

Are you referring to ECM diagnostic trouble codes? Isn't a code 21 a throttle position sensor fault.

Expo

Checking further--you're right--it is the TPS. I was going by the chart on the back of the OBD-1. Thanks for the correction.

RRT vette

Yes, a code 21 on a 85 is the TPS. This means the ECM has seen a voltage outside it's programmed limits. Not necessarily that the TPS is bad but could me misadjusted, poor connection, or open/grounded circuit. I would try the TPS steps below and just for fun you might want to clean the IAC and TB. Never hurts to remove the carbon.


https://www.corvetteforum.com/techti...=195&TopicID=2

https://www.corvetteforum.com/techti...D=55&TopicID=2