I physically separated the female wiring harness from the male connector of the pcm. The female side has a engine side plastic cover which covers were the wiring coming from the engine connects with the female connector. I cleaned the male pins with some MAT cleaner I have. It says it is safe for electrical connections. I sprayed it on the pins and scrubbed them with a tooth brush. I sprayed the face of the female side but my concern is do I have to take the plastic cover off the back of the female portion of the connector and spray cleaner into the back of the female connector as well as through or on the front of the female connector. This would expose were the wiring coming from the engine is plugged into the back of the female connector.

 

Throttle Position Sensor 91 F150 5.8l - Off-Road Forums & Discussion Groups. In this picture under the pink 91 5.8l is the sensor which has a brown and white lead. I called this the egr. it is connected to the face of the exhaust manifold. I checked it because it has a br/w connection.

 

back to the connector there are three sets of ten pins. the connector sits lengthwise on the firewall. all wires enter from the base of the female connector how do I tell which pin is no. 26? count from the top down or the bottom up or do I have to take the cover off of the back of the female connector and find the br/w wire and follow it to the corresponding pin. . ?

 

This should help you out: Ford Fuel Injection » EEC Computers

 

thanks for the pic so if I follow the thought I should connect red to pin 26 and black to ground and get a reading of 5 volts.

 

The sensor with the Brown/White wire is the EGR Valve Position (EVP) sensor. It is another one of the sensors that uses the VREF signal from Pin 26. IIRC you were previously instructed to remove the connectors to the EVP, TPS and map sensors to see if VREF came up to the correct voltage. It sounds like you have cleaned out the PCM connector, now would be a good time to see if the VREF signal is correct with no load on it. If it is good then you can start plugging in one sensor at a time to see which one is pulling own the signal.

There is one more scenario here: The VREF wire could be shorted to ground. With the PCM and sensors unplugged ohm the VREF signal wire to ground, it should be an open circuit.

 

using koeo. then female 26 and br/w wiring for continuity.

 

VREF should be active anytime the key is in the Run or Start position. Pretty easy to meter, then start unplugging connectors to sensors. When checking for a short to ground turn the key to Off, then use the resistance measurement setting on your meter.

 

just call me crazy, but isn't the tps located on the underside of the throttle body. What I see has three leads orange, green and black. The upper manifold were what I think the tps is located under looks like it has a chip knocked off of the corner. Right where the tps sits. Unless the tps is somewhere else. There is no br/wh wire that I can see.

 

The connector from the engine harness to the TPS connector has the wire you are looking for. Unfortunately Ford did not keep the same wire colors from connector to connector in many cases.

Orange is VREF, Signal Return is black, TPS output is Green.

Once you pull off the TPS connector you can measure the Brown/White wire from the engine harness side.....

 

well, tomorrow is another day. I will check the wiring then. The tps had corrosion on the pins so I cleaned them up I'll check the orange lead for vref tomorrow. thanks for hanging with me

 

Make out all checks payable to "cash"

 

I took a vref koeo from all sensor before disconnecting the connections .03v-.05 volts was the average on all sensors. should be 5 volts. I disconnected the computer put a red in the female side 26 and checked resistance and black at connector to each sensor. set meter to 2000 ohms and each cleared to zero. Then I tested pin 26 computer side for voltage koef. red to pin and black to ground and got zero. I had to use a alligator clip to connect the pin to the red side of the meter and grounded the black to the body of the truck. If I physically touched on red connection and the clip while standing on the ground I get a reading of .08 volts. I connected everything back up started the truck rough idle but it idles at 750 and if you put the hammer down the motor does not hesitate and revs right up. comments

 

what powers the computer? when I disconnected the harness did i disconnect the power

 

Yes you did.