I have a 97 HD F250 5.8 motor and E4OD trans. My overdrive light is flashing and its shiftting poorly. It has the old style diagnostic port under the hood not OBDII under the dash. I used a snapon scanner when i plug it in with the key off I can enter all the info as soon as I turn the key on to start the test the scanner shuts off. I also tried the old way with a paper clip to jump the plug and read the flashes and the light won't flash. I checked the ground on the plug and cleaned all connections still not working. Any ideas would be appretiated. I don't even know which of the wires in that plug are supposed to be hot or ground Thanks, Mike

 

If it were like a 95 or older it would be a bad PCM. I have no data on a 97 without OBDII.

 

Are you sure your 97 is not OBDII? I havn't seen a 97 that wasn't mass-air

 

I had a similar problem about a year ago with my '94 f150. The truck was runnig very poorly and when I would try to scan the codes I would either send nothing at all or read the first part of the code sequence and then shut off. When it would shut off it would make the fuel pump turn on and off too. I tried for weeks to figure it out and finally broke down and brought it to a shop. The first thing the mechanic did was cut a connecter off an old ford car he had sitting around and splice it in on mine. He thought the connnector was corroded, no dice. It still wouldn't read codes correctly. After a few days of messin with it he noticed the new O2 sensor that I had installed. That gave him a lead on the problem. The brand new O2 sensor(Bosch) I had install had a short in it, which fried my MAF sensor. He Installed a genuine Ford O2 sensor and a new MAF and everything worked just fine. Including the diagnostic port. Weird I know, but somehow with the two of those thing being bad it wouldn't read codes, even the codes that would indicate they where bad.

The lesson I learned was when it comes to sensors spend the extra $$ and get the genuine parts.

 

I want to say that Ford O2 sensors are made by Bosch...

 

It definitly has an EEC port under the hood not OBDII under the dash. Thanks

 

I thought Bosch was a decent supplier of parts too, but after that experience I am stayin away! As far as making O2's for ford, I don't know. Before I would agree with you, because why would ford make a part that they could save alotta $$ on just buying it from someone who specializes in small parts and sensors. But a Bosch O2 sensor was about $30-$40. And it was junk to start out with. The Ford O2 sensor was like $110 and has worked like a charm ever since. I know the dealer has a way of jacking prices thru the roof, but sometimes ya just gotta bit the bullet and pay for the good stuff. The short in the Bosch O2 caused me to have to shell out even more cash cause it fried my MAF.

 

How did the O2 sensor mess up the MAF, if you don't mind me asking?

 

I just bought scanner for my 87 f150 and I tried and tried it would run in koer but when I started the truck it wouldnt read any codes so i had my 8 year old sit in truck and hold clutch in and it worked! if its a standard try having someone hold clutch in thru the key on engine running process not sure if this helps I know your truck is newer so I am not sure but it helped me

 

I would like to hear this answer also.

This is not possible, he is saying shorting the O2 input of the PCM to ground will take out the MAF ??? sensor. He must have done some sort of conversion, as he should have a MAP sensor.
That is what the O2 sensor does is taking this input of the PCM near ground.
The only common link between the O2 sensor and the MAP (MAF??) sensor is ground.

 

So could this be as easy as a groud problem to the PCM. I got fed up with it and had it towed to a shop to be fixed. They didn't want to touch it because they couldn't get the EEC plug to work either. It just got dropped back off at my house so I am going to start tracing wires. I will post anything I find. thanks for the imput so far

 

Bill, there were a few 94 trucks with factory mass-air. Even if something like what you suggested occurred, it seems like it would be an internal computer problem rather than frying the mass air meter itself.

 

I did not say anything occurred. I just said an O2 sensor can not make and MAP or MAF sensor go bad.

 

I was referring to the shorts you talked about happening in post #10...

I'm with you...I don't see how even a short could cause any problems between the O2 sensor and MAF or MAP either one.

 

I fixed the problem. After a few hours with an OHM meter and all the wires tested out OK I found a local salavge yard that had a computer with the right numbers. I put it in it runs and shifts fine no warning lights. Thanks Again for the replys