NEWBIE,


Code 12-RPM unable to reach upper test limit

Code 13-RPM unable to reach lower test limit

Code 21-ECT out ot self test range

Code 16-IDM signal not received


Specs. 1988 EFI speed density 5.0
Early Bronco, w/C4. It runs ok, just trying to ID and fix these codes.

I recently pulled these codes from my scanner. I’d like to know where to go from here.
The RPM seems to be related in most of the faults. Where should I start? Thanks in advance.

Dave

 

Code 21 I would look at the Engine Coolant Temperature sensor, maybe bad, or wiring problem

 

Sounds like a bad Engine wiring harness.

 

Come to think of it, i really have very little idle control.
i'll start looking into the wiring harness and Coolant Temperature sensor. Thanks again.