Code 67 / Ngs Wiring Issue

Discussion in 'Fox 5.0 Mustang Tech' started by mkk50, Jul 12, 2014.

  1. I have been trying to fix a code 67 issue on my car for a while, and need some help/direction. I measured the voltage on pin 30 at the computer, and see 5 volts there. I then tested the voltage at the NGS sensor on the transmission (manual), and dont see the corresponding 5 volts. I ohm tested the sensor and it appears to be working fine, and also the other lead ohms checks to the SIG RTN line fine. I believe there is a short/bad connection to the computer, but I cannot find where the connector(s) would be. The NGS sensor connection goes into the car slightly in-front and below the shifter, and the only wires I could find near there run backwards towards the rear of the car. Does anyone know where the other connections would be for the NGS sensor to the computer?
  2. Do you have problems with idle surge and bucking while driving ?or it runs fine but you just have the code?Because if your check codes in first gear it will give a code 67 every time. Also is the code 67 a memory code?
  3. Car has a hanging idle sometimes when driving. I was checking the codes with the car in neutral and also tried pressing down the clutch. I get that code when trying to pull the KOER codes.
  4. Try taking the battery out and clean the ground for the computer ..the computer ground is behind the battery. I had a problem with a code 96 for the fuel pump circuit the code would just come and go i check/tighten up every ground wire i could find. And the code has not been back ..knock on wood it could be just bad wiring/a bad /loose ground wire.
  5. Code 67 –
    Revised 2 Nov 2012 to add definition of the NSS functions for both 5 speed and auto transmissions

    External evidence from other sources claims that a code 67 can cause an idle surge condition. Do try to find and fix any issues
    Cause of problem:
    clutch not depressed (5 speed) or car not in neutral or park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code may prevent you from running the Key On Engine On tests.
    with the switch and wiring if you get a code 67.

    What the NSS (Neutral Safety Switch) does:
    5 speed transmission: It has no connection with the starter, and the engine can be cranked without it being connected.
    Auto transmission: It is the safety interlock that prevents the starter from cranking the engine with the transmission in gear.
    What it does for both 5 speed and auto transmission cars:
    The computer wants to make sure the A/C is off due to the added load on the engine for the engine running computer diagnostic tests. It also checks to see that the transmission is in Neutral (5 speed and auto transmission) and the clutch depressed (T5, T56, Tremec 3550 & TKO)). This prevents the diagnostics from being run when the car is driven. Key On Engine Running test mode takes the throttle control away from the driver for several tests. This could prove hazardous if the computer was jumpered into test mode and then driven.

    The following is for 5 speed cars only.
    The NSS code 67 can be bypassed for testing. You will need to temporarily ground computer pin 30 to the chassis. Computer pin 30 uses a Lt blue/yellow wire. Remove the passenger side kick panel and then remove the plastic cover from the computer wiring connector. Use a safety pin to probe the connector from the rear. Jumper the safety pin to the ground near the computer.
    Be sure to remove the jumper BEFORE attempting to drive the car!!!


    O2 Sensor harness interchange and modification

    Originally Posted by 302EFI

    Revised 16-Oct-2011 to add O2 sensor harness warnings
    The wires for the 02's and low oil did not change throughout the years, they are all in the same place.
    The main ones you need to worry about are (on the harness end (ECU) that plugs into the 02 plug) is:
    \- 1. Lightblue / yellow
    - 2. White / Purple
    - 3. Purple / Yellow
    The White/Purple & Purple/Yellow gets looped for a automatic ECU
    The Purple/Yellow & Lightblue/Yellow for a manual ECU

    See for more O2 sensor wiring harness info

    Basic premise to use with transmission swaps:
    Only run a 5 speed trans O2 harness with an A9L. Do not run an Auto O2 sensor harness with an A9L. Doing so will damage the computer’s internal signal ground.
    Only run an Auto trans O2 sensor harness with an A9P in a car that has an Auto trans. Using a 5 speed trans O2 sensor harness with an Auto trans will cause no crank problems.
    See for Joel5.0’s fix to the computer internal signal ground.

    90 model year harness only works with 90 model cars without inspection/rework.
    The 4 cylinder O2 harness uses 4 wire O2 sensors. It probably won’t work correctly without modifying it.
  6. Thanks. As a reference since it might help others, after tracing the wires and checking my O2 harness, i realized that the loopback that was in that harness was for the NSS/Clutch switch to the computer. I cleaned up the O2 harness connections and it fixed my code 67. I have a 91 with a manual transmission, and I have the O2 harness on the right in this picture, with the blue/yellow wire.