no codes with engine on

crazy-ed-57

New Member
Jul 28, 2004
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sidney, oh
i have a 1986 mustang gt and i'm trying to pull codes with a code reader. i can pull up code(s) with engine off and key on (koeo test) but not with engine on (koer test). the only code i'm getting is 67 (invalid signals are being received from neutral drive switch...i'm getting this code because i switched from a automatic tranny to a manual tranny and hot wired the neutral drive switch so car will only start with clutch pedal in...i couldnt find plug for switch). has anyone else had this problem with no codes with engine on? it won't give any tests at all with engine on..example: ignition advance test and so on...wont even give me a 11 code... help.....
 
I have the same exact issue. I get a 67 on KOEO. I didnt switch to a manual from an auto though. Its always been a standard, so I'm not sure what is causing the 67 to show. When I try the KOER test, the car makes a grinding sound like its trying to start, then almost dies. It corrects and the scanning tool does nothing. What kind of scanner are you using?
 
I also have an 86 and picked up the "Wallmart Special" code reader this afternoon. I'm having the exact same issue. KOEO works fine. I get the same code 67 then the all celar code (11). When I try to run the KOER test, I get nothing. I've even tried putting the reader in to test mose first then providing the ground manually to put the computer into test mode. The engine surges (almost dies) then recovers (so I know it's at least going into test mode). Then nothing. I get no further indication from the reader that anything is happening. I've tried to put it into the cylinder balance test by depressing the accelerator momentarily but it won't enter into that test either. Anyone able to shed some light on this?
 
Most likely cause is the neutral safety switch or A/C wiring is damaged. Check out pins 10 & 30 on the diagram.

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See http://www.autozone.com/servlet/UiB..._us/0900823d/80/16/71/3c/0900823d8016713c.jsp for more wiring diagrams
 
I was talking with GRN92LX last night and he turned me onto the same switch (which I do believe is the problem) but brings me to my next query. If it's wired as the diagram shows it, then how is it The starter is able to engage if that switch in working correctly? It looks to me like the neutral safety switch is wired in series with the clutch switch. If I'm able to crank the motor over when I depress the clutch then where is the starter getting power from?
 
As old as these cars are, unless you are the first owner, someone before you may have done some sneaky things with the wiring.

Don't forget pin 10 on the computer which goes to the A/C. It will cause the same 67 code.
 
Yeah... I'd already tried setting the A/C switch in numerous different postions including "OFF" to try and limit that possibility. After talking with GRN92LX (who had the same problem) I'm reasonably convinced that the tranny neutral switch is the problem but just can figure out "why" by looking at the wiring diagrams. There must be something in that switch circuit that is not be shown in the diagrams (another route for electricity flow, perhaps through the ignition switch) that's not accurately displayed). There may even be some kind of bypass within the switch itself. As for previous owners.... My mother is the only one. No one else has ever turned wrenches on this car besides me and the occational shop that installed/rotated/balanced tires and that sort of thing. I'd like to have a accurate diagram of the switch internal workings to see if I can install a test jumper to check switch operation. There's nothing that I've seen so far that shows what switches are normally open, normally closed, etc...
 
Daggar said:
If it's wired as the diagram shows it, then how is it The starter is able to engage if that switch in working correctly? It looks to me like the neutral safety switch is wired in series with the clutch switch.
Hmmm, I always thought the neutral safety switch (for autos)/clutch safety switch (for sticks), both of which are part of the starter interlock circuit, were different than the mechanism in the trans which notes whether the car is in gear. :shrug:
 
HISSIN50 said:
Hmmm, I always thought the neutral safety switch (for autos)/clutch safety switch (for sticks), both of which are part of the starter interlock circuit, were different than the mechanism in the trans which notes whether the car is in gear. :shrug:

Your guess is as good as mine man. I have a manual (of course) and the switch in the tranny does exist and is doing something. If the wiring diagram is correct, then I should not be able to start the car if that switch is not functioning yet.... "VROOOOOOOOM" it goes. The diagram that jrichker shows is slightly different than the one in the Haynes manual. The Haynes shows the switch for an automatic compolete with a 4 position switch (R-1-2-3-D). I'm with you... big, fat, :shrug:
 
mustangmax said:
I was able to get my problem solved and then all of the other tests could be completed. I cleaned up the contacts and switches on the tranny and the 67 code dropped.


I'm going to try that just as soon as I get a chance to jack up the car and get a good hand hold and look at it.