Engine **FIXED** Code 67 preventing KOER test... but clutch is pressed and A/C is deleted??

TomOsiris

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May 19, 2019
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Hey guys,

I'm back again after getting my head gaskets replaced. Used a new mechanic who seemed very knowledgeable, however my car is now throwing codes that were not there prior to the hg replacement, and check engine light is always on now after about 5-10 minutes of driving, whereas it was never on previously.

The first issue is KOEO code 67, which is preventing me from running KOER tests. As far as I understand, this can have 3 possible causes..
-Clutch safety switch (clutch not depressed)
-A/C is on (or for some reason the computer thinks it is)
-Neutral sensing switch on the T5

Just to clarify a few details, this car is NOT a t5 conversion, it is a factory t5 car, and it is a 1989 so it is NOT a speed density conversion, factory MAF.
I have done some prior research and found that this code can be caused by issues regarding these swaps so just want to get that out of the way.

I was able to ground pin 30 at the ECU in order to run a KOER test, however this is extremely inconvenient and I really need to get rid of this code 67 so I can perform regular tests and get to the bottom of the rest of my issues (lean codes 41+91)

Code 67 is present whether or not I hold the clutch in while performing the KOEO test, I have tried this many times.
I believe the cause to be either the neutral sensing switch, or the computer thinks the A/C is running.
The A/C is deleted but is there any reason for the computer to think its on? Or can I rule this out entirely?
Would a failed neutral sensing switch cause a code 67 even when the clutch is fully depressed?

I do have other codes I need to take care of, but I can't even tell what they are until I can get this code 67 taken care of for good.
Appreciate any responses, thanks in advance!
 
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Mustang5L5

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Mod Dude
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The AC system monitoring is through the ECU. If it's off, it's off. There is no wiring associated with this particular aspect of generating the code 67 so i'm 99% sure you can cross this off the list of suspected causes.

Have you tested both the clutch switch and the NGS switch on the T5 to confirm that they are good and do close when they are in neutral/clutch in?

What I would do is test those two devices. If they work, i would ground the light blue/yellow wire at the clutch switch (and trans switch) which would ground out pin 30. If it works it tells you you have continuity back to the ECU and there isn't a break in the wiring.

If you have continuity, and if both the clutch switch and trans switch work, i would test the black/white which should have continuity back to pin 46.


1655918117687.png
 

TomOsiris

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May 19, 2019
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The AC system monitoring is through the ECU. If it's off, it's off. There is no wiring associated with this particular aspect of generating the code 67 so i'm 99% sure you can cross this off the list of suspected causes.

Have you tested both the clutch switch and the NGS switch on the T5 to confirm that they are good and do close when they are in neutral/clutch in?

What I would do is test those two devices. If they work, i would ground the light blue/yellow wire at the clutch switch (and trans switch) which would ground out pin 30. If it works it tells you you have continuity back to the ECU and there isn't a break in the wiring.

If you have continuity, and if both the clutch switch and trans switch work, i would test the black/white which should have continuity back to pin 46.


1655918117687.png
Thanks for the response, much appreciated! as I am currently at the limit of my understanding with this issue...
Please be patient as I am not very knowledgeable when it comes to electrical and the testing involved, etc.

Just so I am understanding correctly, with the switches wired in parallel, EITHER of them should tell the computer its ok to run a KOER test?
Meaning that if everything was working 100% as it should, the trans would need to be in neutral, OR the clutch pushed in, but NOT BOTH, correct?

My confusion is coming from the fact that BOTH switches are not working correctly, and this happened simultaneously?
I am not sure how this could have happened, considering I have run KOER tests many times in the past without issue or code 67.
Also, I stuck a fuse in the clutch switch and still got code 67, what would this indicate? That the computer is not receiving the signal from the clutch switch?
Or that the clutch switch is not working at all?

As mentioned above, grounding pin 30 at the ECU allowed me to run the KOER test.
So you are saying if I ground the wire at the switch, and that eliminates the code, that would indicate continuity to the ECU?

What is the proper method for testing that switches are working correctly? sorry if this is a dumb question.

Also, what does pin 46 have to do with this issue exactly?
To my (limited) understanding this code is caused by lack of signal to pin 30?
 

Mustang5L5

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Mod Dude
Feb 18, 2001
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Just so I am understanding correctly, with the switches wired in parallel, EITHER of them should tell the computer its ok to run a KOER test?
Meaning that if everything was working 100% as it should, the trans would need to be in neutral, OR the clutch pushed in, but NOT BOTH, correct?

Correct. Either switch being closed will complete the circuit. It's telling the ECU the car is in neutral, either with the trans being in neutral, or the clutch in. You only need one condition to be met

My confusion is coming from the fact that BOTH switches are not working correctly, and this happened simultaneously?
I am not sure how this could have happened, considering I have run KOER tests many times in the past without issue or code 67.
Also, I stuck a fuse in the clutch switch and still got code 67, what would this indicate? That the computer is not receiving the signal from the clutch switch?
Or that the clutch switch is not working at all?

Since grounding pin 30 works, it means that you either have both of those switches failed, or the wire is broken/disconnected somewhere. Plugging the fuse in has no effect because the circuit is not complete.


As mentioned above, grounding pin 30 at the ECU allowed me to run the KOER test.
So you are saying if I ground the wire at the switch, and that eliminates the code, that would indicate continuity to the ECU?

What is the proper method for testing that switches are working correctly? sorry if this is a dumb question.

So what you are doing is testing the same wire that connects to pin 30 further down the line away from the ECU. This will tell you if you have a break in the wiring between the switches and the ecu. If the wiring is good, you can focus on the switchs, or the pin 46 side of things.

Basically you are testing portions of the circuit in an attempt to isolate the bad portion by testing to see which part of the wiring works as intended


Also, what does pin 46 have to do with this issue exactly?
To my (limited) understanding this code is caused by lack of signal to pin 30?

The wiring is a loop. in this case the loop starts (or ends) at pin 46 and pin 30. I'll simplify heavily here. Think of the wiring like a road and the two switches like bridges. You leave from pin 30 on the ECU and drive down the road to the switches which cross the river. In order to get across, you only need one of the bridges to be down (switches closed). If one is, you cross is and keep driving down the road until you reach pin 46. Circuit is closed, no code 67.

Now, the only think that would prevent you from making the complete circuit is that the wiring is broken/disconnected somewhere, or both the bridges are up. (switches not closing when the clutch is pressed in, or trans in nuetral). Make sense?

So really the troubleshooting here is to test the two switches and verify the wiring is intact. It would be one hell of a coincidence for both to be dead.
 
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Mustang5L5

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Here's a bigger view of the wiring diagram. The yellow is tracing out the cicuit path as it travels from pin 30 to pin 46. The red circled numbers are connector numbers, of which could be disconnected or making a poor connection.

You can use a digital multimeter to test from the blue circles points back to pin 30 itself at the ECU to test the wire between those points. Similarly you can check continuity from the black circled areas back to pin 46.



1655921213698.png
 
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TomOsiris

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Correct. Either switch being closed will complete the circuit. It's telling the ECU the car is in neutral, either with the trans being in neutral, or the clutch in. You only need one condition to be met



Since grounding pin 30 works, it means that you either have both of those switches failed, or the wire is broken/disconnected somewhere. Plugging the fuse in has no effect because the circuit is not complete.




So what you are doing is testing the same wire that connects to pin 30 further down the line away from the ECU. This will tell you if you have a break in the wiring between the switches and the ecu. If the wiring is good, you can focus on the switchs, or the pin 46 side of things.

Basically you are testing portions of the circuit in an attempt to isolate the bad portion by testing to see which part of the wiring works as intended




The wiring is a loop. in this case the loop starts (or ends) at pin 46 and pin 30. I'll simplify heavily here. Think of the wiring like a road and the two switches like bridges. You leave from pin 30 on the ECU and drive down the road to the switches which cross the river. In order to get across, you only need one of the bridges to be down (switches closed). If one is, you cross is and keep driving down the road until you reach pin 46. Circuit is closed, no code 67.

Now, the only think that would prevent you from making the complete circuit is that the wiring is broken/disconnected somewhere, or both the bridges are up. (switches not closing when the clutch is pressed in, or trans in nuetral). Make sense?

So really the troubleshooting here is to test the two switches and verify the wiring is intact. It would be one hell of a coincidence for both to be dead.
Man, I have to say this is a great response and I really do appreciate you taking time out of your day to help me with this.

So because I am seeing the code, there is no continuity between pin 30 and pin 46.
This means that either BOTH switches are not working (???) or that the wiring is compromised at some point along the route.

Looking at the diagram above, I am assuming that the 2 points with blue circles are the 2 switches, one being on the clutch pedal and the other on the transmission.

I understand that because grounding at pin 30 worked, then testing farther away from pin 30 would help me isolate where the connection is broken.
i.e., if I ground the wire at the clutch switch, and still get the code, then the wire is disconnected at some point between the switch and the ECU pin 30.

But how exactly would I test the switches themselves?
If I determine that the wiring is intact, does that automatically indicate that the switches are bad?

What is the best way to test the wire, should I just tap into it with a needle and some gator clips to a ground point?
Or is there a better way?
Also, as far as testing from the blue circled points back to pin 30.. Trying to think of how to go about this..
I assume that I would need to tap an extension wire to pin 30 then use the voltmeter to test continuity from the switch back to the pin?

I do have a bad habit of getting frustrated and throwing parts at problems..
If I were to replace BOTH the clutch switch and NSS/NGS switch, and STILL have the code..
Then I would know for a fact I have a wiring problem?
 

Mustang5L5

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Mod Dude
Feb 18, 2001
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Do you have a digital multimeter? Because you really need one for this testing. You can use it to test if the wiring is intact by testing continuity.

If you don't have one, snag one off amazon. Cheap ones are ok for this low-voltage car wiring stuff.

You test continuity by touching one lead to each side of the switch and activating it. If there is an electrical connection, the meter will make a tone. Same with testing wiring. Test each end of the wire with the leads and if the path is continuous, you get a tone.

Amazon product
View: https://www.amazon.com/INNOVA-3300-Hands-free-Digital-Multimeter/dp/B001O1X65A/ref=asc_df_B001O1X65A?tag=bingshoppinga-20&linkCode=df0&hvadid=80058242473102&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4583657821659011&psc=1
 

TomOsiris

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May 19, 2019
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Do you have a digital multimeter? Because you really need one for this testing. You can use it to test if the wiring is intact by testing continuity.

If you don't have one, snag one off amazon. Cheap ones are ok for this low-voltage car wiring stuff.

You test continuity by touching one lead to each side of the switch and activating it. If there is an electrical connection, the meter will make a tone. Same with testing wiring. Test each end of the wire with the leads and if the path is continuous, you get a tone.

Amazon product
View: https://www.amazon.com/INNOVA-3300-Hands-free-Digital-Multimeter/dp/B001O1X65A/ref=asc_df_B001O1X65A?tag=bingshoppinga-20&linkCode=df0&hvadid=80058242473102&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4583657821659011&psc=1

Yes I do have a good quality multimeter, the problem more lies in my lack of understanding.

So If I am understanding correctly.. there are 2 wires attached to the switch, attach probes to each wire.
Now if I close the switch (press clutch, stick a fuse in it, etc) I should hear a beep.

Same for NSS/NGS, probe into both wires, put car in neutral, should beep? If not, no connection
 

TomOsiris

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Here's a bigger view of the wiring diagram. The yellow is tracing out the cicuit path as it travels from pin 30 to pin 46. The red circled numbers are connector numbers, of which could be disconnected or making a poor connection.

You can use a digital multimeter to test from the blue circles points back to pin 30 itself at the ECU to test the wire between those points. Similarly you can check continuity from the black circled areas back to pin 46.



1655921213698.png
Ok, so I am back with some developments after doing some testing based on your recommendations.

Firstly, the NSS on the trans is confirmed working properly.
I disconnected the plug, then tested for continuity with the trans in neutral and confirmed the switch was closed.
Just for reassurance, I had my gf put the car in and out of gear a few times with the tester in place, and there was only continuity with the trans in neutral, as you would expect with a proper functioning switch, so we can rule that out.

Next, I was going to test the switch at the clutch pedal, but I actually had a different idea once I got under there..
What if I tested plug that goes to the sensor instead? What would this indicate?
So I tested the two prongs in the connector that plug into the clutch switch and... there was continuity there as well?
Based on the above diagram, would this indicate that I have continuity between pin 30 and pin 46 at the ECU?
How else could there be a connection between these two wires, if not through the ECU? Unless I am missing something?

Also working with the notion that only ONE condition needs to be met (clutch pressed OR in neutral) and my NSS is confirmed working, and I have continuity from pin 30 to pin 46....

Does my car think that the A/C is on???
 

Mustang5L5

Put lubricant all over the balls
Mod Dude
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Was the trans switch plugged in? Was the car in nuetral? If so, you tested continuity from both sides of the plug through the transmission switch if it happened to be in neutral and not in gear.

Repeat the test with the trans in gear, and the trans switch should be open.
 

TomOsiris

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Was the trans switch plugged in? Was the car in nuetral? If so, you tested continuity from both sides of the plug through the transmission switch if it happened to be in neutral and not in gear.
I think you may have misunderstood how I phrased that..

Unplugged trans switch, testing trans switch for continuity at plug.
in Neutral BEEEEEEEP
in gear no beep
Trans switch is working
basically, confirmed that the switch closes in neutral, and opens when put into gear, as it should

Sorry if I wasnt clear with how I worded that originally
 
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TomOsiris

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Was the trans switch plugged in? Was the car in nuetral? If so, you tested continuity from both sides of the plug through the transmission switch if it happened to be in neutral and not in gear.

Repeat the test with the trans in gear, and the trans switch should be open.
Next, I was going to test the switch at the clutch pedal, but I actually had a different idea once I got under there..
What if I tested plug that goes to the sensor instead? What would this indicate?
So I tested the two prongs in the connector that plug into the clutch switch and... there was continuity there as well?
Based on the above diagram, would this indicate that I have continuity between pin 30 and pin 46 at the ECU?
How else could there be a connection between these two wires, if not through the ECU? Unless I am missing something?
so I have ruled out the neutral switch itself being a cause of the issue.
Also due to what I have written above ^^^ I feel as thought this indicates that there are no breaks in the wiring circuit, as I have continuity between the black wire (pin 46) and the blue wire (pin 30) at the clutch switch plug.
So if there is a complete circuit there when I close the switch with a fuse for example and STILL see the code..

That would only leave A/C as a possible cause?? Am I missing something?
 

Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
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I think you may have misunderstood how I phrased that..

Unplugged trans switch, testing trans switch for continuity at plug.
in Neutral BEEEEEEEP
in gear no beep
Trans switch is working
basically, confirmed that the switch closes in neutral, and opens when put into gear, as it should

Sorry if I wasnt clear with how I worded that originally


That was clear. I was referring to when you tested the clutch switch.

You said you didn't test the clutch switch, but instead connected the meter to both wires in the plug? Is that correct? If so, what was the state of the transmission switch? Was it in neutral at the time, or in gear?

Reason I ask is because if you tested here where the two red circles are, but the trans was in nuetral at the time, then you would just be testing continity back through the trans switch which would be closed in neutral. Make sense?

1656012256311.png



That would only leave A/C as a possible cause?? Am I missing something?

Except that grounding pin 30 eliminates the code 67 when you run the ECU codes. The AC should override that, but it isnt




Either way, you've tested the trans switch, so with the trans in neutral you should have continuity from pin 30 to 46. I really think you should check the wiring itself. Top red circle to pin 30, and bottom red to pin 46. To avoid any possible continuity through the ECU, i would do this test with the ECU unplugged.
 
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TomOsiris

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That was clear. I was referring to when you tested the clutch switch.

You said you didn't test the clutch switch, but instead connected the meter to both wires in the plug? Is that correct? If so, what was the state of the transmission switch? Was it in neutral at the time, or in gear?

Reason I ask is because if you tested here where the two red circles are, but the trans was in nuetral at the time, then you would just be testing continity back through the trans switch which would be closed in neutral. Make sense?

1656012256311.png





Except that grounding pin 30 eliminates the code 67 when you run the ECU codes. The AC should override that, but it isnt




Either way, you've tested the trans switch, so with the trans in neutral you should have continuity from pin 30 to 46. I really think you should check the wiring itself. Top red circle to pin 30, and bottom red to pin 46. To avoid any possible continuity through the ECU, i would do this test with the ECU unplugged.
Ok , I am following you 100% now.
Just picked up a fresh pack of test wires and sewing needles, so I will be back at it tonight.

Is there a risk of damage testing continuity back through the ECU?
I am going to do as you recommended and test for continuity from the switch back to the ECU.

Thanks again for all the help so far, I feel as if I continue narrowing things down I am bound to find the cause eventually.
 

Mustang5L5

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Mod Dude
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Damage risk is low since we are dealing with grounds here, but my worry is false continuity readings through the ECU throwing off what you are trying to chase down.

I do have a spare A9L on the shelf. I can confirm in a bit that 30 and 46 are normally open.
 

TomOsiris

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Damage risk is low since we are dealing with grounds here, but my worry is false continuity readings through the ECU throwing off what you are trying to chase down.

I do have a spare A9L on the shelf. I can confirm in a bit that 30 and 46 are normally open.
I just had my ECU rebuilt a few months ago, so I would be leaning away from thinking something was wrong there (hopefully anyways)...

but what do you mean by pin 30 and 46 are normally open?
Open meaning what exactly in this scenario?
If I took the ECU and stuck one test lead into 30 and one into 46, it should have continuity through the ECU, or not?

I am also starting to think there may be a wiring issue, in which case I assume I would be chasing the entire harness and testing continuity along the way..