Questions and Answers

Ford Escort Has No DTCs At All Q. Dear Mr. Ciulla, 1993 Ford Escort, 1.9 liter, automatic transmission, 46,000 miles, fuel injection, P/S and A/C. This car is only getting about 15 miles per gallon (city) and has been that way since we purchased the car (used) five years ago. The car had always passed the federal emissions tests but failed the HO test the last time we had it tested.

I figured the best approach to finding out what was wrong (with both problems) was to examine the "Trouble Codes" sent back from the Diagnostic Test Connector located under the hood, behind the battery. I hooked up my VOM between the battery and the "STO" pin on the connector and jumpered the "STI" pin as instructed in my "Haynes Ford Escort and Mercury Tracer, 1991 to 1995, Automotive Repair Manual" and followed all instructions closely.

My problem is there are NO CODES coming from the Self Test Output (STO) pin. The repair manual list all of the various codes that should be available and also shows "No Codes: Unable to initiate Self Test or Unable to output codes".

Can you suggest a reason for why the EEC is not outputting any codes at all? I do not even get code 11 . The STO signal starts out "HI" at 12 volts but as soon as the ignition switch is switched "ON" ( without starting engine), the STO signal drops to "LO" at or near Zero volts and remains there.

Thank you for any help you can provide.
Dave
Chicago, Ill

A. I would have the system scanned with a scan tool, preferably the Ford scan tool to see if there are any codes. There may be a wiring problem with the self test circuit or the PCM has kicked the bucket.