Help with codes, please!

Discussion in 'Fox 5.0 Mustang Tech' started by 46defense, Dec 2, 2003.

  1. Ok, here goes, Years ago I had a light and checked the codes. I don't remember for sure what they were but they definately had something to do with the EGR. I replaced the egr valve and that didn't seem to get rid of the light so I changed the switch or whatever it is right by or on the egr valve. I unhooked the battery for a while and then I had no light. Fixed! $100 total. Everything was fine until about 3 years ago when I installed my PMS. The light came back on. I ran the codes and got the same ones that i had before. I didn't know what was going on but decided that I didn't want to spend the $100 again because I just had and didn't figure anything could be wrong with my egr stuff because it was basically brand new. The car sat for the better part of two years after moving to Florida and driving my new 01 gt. I traded the 01 in on my wifes new car and I've been driving the car now for a couple of months. The light has been on constantly the whole time. The day after I finally bought my own Actron code reader the light decided to start going on and off at times but is still mostly on all the time. I've just noticed it going on and off a couple of different times. I just bought an Innovate wide band and before installing it I wanted to see if I could finally get rid of the check engine light first. I ran the koeo codes and got a 31 and a 96. 31 is related to the egr and the 96 says thermactot air sytem problem-right (passenger) side air flow will not bypass, or fuel pump circuit failure, or high speed fuel pump relay circuit failure. I didnt run the koer test yet for one because it says to turn off all electrical loads and my electric fan runs whenever the key is on. I guess I can just unplug it at the fan? that shouldn't bother anything should it? Anyway, anybody got any idea what it could be with the air thermactor? I just replaced a hose when I changed my headers a couple weeks ago. I noticed that the equal lengths had burned a hole in it. I hoped this might get rid of my light. It didn't. What else is replaceable in that system that could be causing the light? Also I installed a T-rex when I installed the pms which is when the light came on, but I don't know what could be wrong with any of that. I mean, it's been dyno tested at Anderson Ford and driven for 3 years since that install. Just wondering because of the mention of fuel with the 96 code and the fact that I was working on the fuel sytem right before the light came back on. I still can't imagine anything being wrong with the egr, but :shrug:
    I'll probably do the koer test tomorrow but does anbody have any ideas so far or help as far as what is the possible problem with the air thermactor or anything at all. I'm pretty sure that nothing is affecting the way the car runs, but I just want to get rid of the dang light. Thanks, and sorry so long. I just wanted to give you guys as much info to go on as I could, Russ
  2. ttt, Please
  3. CODE: 31 (KOEO) - EVP circuit below minimum voltage. Vref missing or broken wire or bad contact in circuit. Check for 5 volts on the orange/white wire. With the sensor removed from the EGR and still connected, press the plunger and watch the voltage change on the brown/lt green wire. Check for the same results on pin 27 on the computer. Fix this problem before attempting to fix any other codes, as the EGR may be opening under computer control and leaning out the air/fuel mixture. Quick test of this leaning out the air/fuel mixture theory: remove the vacuum line from the EGR or install EGR blocking plate. Drive car and see what happens.

    Code 96 – Fuel pump monitor circuit shows no power - Power / Fuel Pump Circuits
    (Stored Memory code - Service 87 code first if present) Fuel pump relay or battery power feed was open - Power / Fuel Pump Circuits
    Look for power at the fuel pump - the fuel pump has a connector at the rear of the car with a pink/black wire and a black wire that goes to the fuel pump. The pink/black wire should be hot when jumpered to the test position. . To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground. for a description of the test connector. it. No voltage when jumpered, check the fuel pump relay and fuse links.