P0689 issues

AnotherS197GT

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I've been talking to the valve dropper and my son's car drops a valve yesterday. Lol

You're welcome?

Anyways, I'm still waiting to hear back from a couple guys at work to see if they have some insight into this. My gut feeling is that this is all calibration based because your PCM is looking for things it shouldn't have (manual car switch inputs for the cruise control) and is setting a DTC that, as far as I can tell, didn't exist for 05 Mustangs. At this point, I would suggest load testing the power and ground circuits to the PCM to ensure they're all functioning correctly. Do you know how to do that?
 

05stroker

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You're welcome?

Anyways, I'm still waiting to hear back from a couple guys at work to see if they have some insight into this. My gut feeling is that this is all calibration based because your PCM is looking for things it shouldn't have (manual car switch inputs for the cruise control) and is setting a DTC that, as far as I can tell, didn't exist for 05 Mustangs. At this point, I would suggest load testing the power and ground circuits to the PCM to ensure they're all functioning correctly. Do you know how to do that?
No I do not, but I learn fast, school me please.
 

AnotherS197GT

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You'll need a small light bulb, usually a 9004 or something similar will work. You'll supply power along the circuit that you want to test to one side of the bulb and ground to the other side of the bulb. If the bulb lights brightly, then you're probably getting 10V+. Bright bulbs are usually an indicator of good power, but modules behave oddly if they're not getting all the power they need. They may "work" but will do weird stuff. You can (and should!) test this by performing a voltage drop test, where you place one lead of your multimeter on the power side before the load (you want to get as close to the bulb as possible), then put the other lead on the ground side directly after the bulb. You will want to see most of the voltage dropping over the load.

For example, if you're using a 12V battery to provide power, you will want to see about 11.5V on your meter when reading on either side of the load. If you're seeing 10V, that means you're dropping 2V across the power and ground circuits. You can figure out which one by placing your lead on the voltage source then placing the other right before the load. In a circuit with low resistance, less than 0.3V should be consumed by the circuit. So again, if you're using a 12V battery, you'd expect to get a reading of about 0.3V (or less) on your multimeter since a multimeter measures the difference in voltage between two points. The same test is completed on the ground side, with one lead directly after the load and one lead at the end of the ground.

So, looking at the 05 wiring diagram, I think you'll want to focus mostly on the PCM Power Relay #2. You would want to disconnect the PCM connector C175B and connect your test bulb to pin 35, then attach a ground to the other side of the bulb. The best thing to do would be to use a PCM ground so that you can test the ground side of the harness as well. Then you would want to close the PCM power relay so that you can test the whole circuit. Then, you would repeat the same test on pins 36, 45 and another PCM ground. The grounds should be on pins 10, 47, 48, 49, and 50.
Screen Shot 2019-03-13 at 8.17.29 PM.png

I would also load test the circuits between the PCM key-off relay and C175B. The key-off relay should be supplied constant power and ground to the coil side, then the switched side receives hot in run or start power from the SJB. For whatever reason, this relay supplies voltage to pins 35 and 36 of C175B too.
Screen Shot 2019-03-13 at 8.30.31 PM.png Screen Shot 2019-03-13 at 8.30.45 PM.png
 
Last edited:

05stroker

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You'll need a small light bulb, usually a 9004 or something similar will work. You'll supply power along the circuit that you want to test to one side of the bulb and ground to the other side of the bulb. If the bulb lights brightly, then you're probably getting 10V+. Bright bulbs are usually an indicator of good power, but modules behave oddly if they're not getting all the power they need. They may "work" but will do weird stuff. You can (and should!) test this by performing a voltage drop test, where you place one lead of your multimeter on the power side before the load (you want to get as close to the bulb as possible), then put the other lead on the ground side directly after the bulb. You will want to see most of the voltage dropping over the load.

For example, if you're using a 12V battery to provide power, you will want to see about 11.5V on your meter when reading on either side of the load. If you're seeing 10V, that means you're dropping 2V across the power and ground circuits. You can figure out which one by placing your lead on the voltage source then placing the other right before the load. In a circuit with low resistance, less than 0.3V should be consumed by the circuit. So again, if you're using a 12V battery, you'd expect to get a reading of about 0.3V (or less) on your multimeter since a multimeter measures the difference in voltage between two points. The same test is completed on the ground side, with one lead directly after the load and one lead at the end of the ground.

So, looking at the 05 wiring diagram, I think you'll want to focus mostly on the PCM Power Relay #2. You would want to disconnect the PCM connector C175B and connect your test bulb to pin 35, then attach a ground to the other side of the bulb. The best thing to do would be to use a PCM ground so that you can test the ground side of the harness as well. Then you would want to close the PCM power relay so that you can test the whole circuit. Then, you would repeat the same test on pins 36, 45 and another PCM ground. The grounds should be on pins 10, 47, 48, 49, and 50.
View attachment 69243

I would also load test the circuits between the PCM key-off relay and C175B. The key-off relay should be supplied constant power and ground to the coil side, then the switched side receives hot in run or start power from the SJB. For whatever reason, this relay supplies voltage to pins 35 and 36 of C175B too.
View attachment 69244 View attachment 69245
Thanks for the detailed response, I will check it this weekend.
 

AnotherS197GT

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No problem!

FYI, I checked out HP Tuners and all these DTCs can be disabled in HPT. I’m not sure if Manuel can edit a file in HPT and port it over to SCT with the DTCs shut off, but the ability to disable them in some form or another does exist.
 

swflastang05

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Damn that's some GOOD info! Dylan, I had that same code last year P0689 along with some clutch pedal codes IIRC P0830 and PO833, they just showed up one time when I was using an X3. I troubleshot it for weeks finally swapped to an X4 (just b/c I got a good deal on a used one) and the codes all went away, there's no logical explanation at all for that. I have the same deal as Billy, 05 original auto car with BKT3 original strategy flashed to CTC3 via Lito for 4r swap a few years ago. There were no issues for a couple years then all of a sudden the codes showed, but again went away by doing nothing other than swapping to an X4. I'm sure that info won't help much but thought I would mention just in case.
 

Stellan

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Hey! I've got a p0689 on an 05 with the SCT X4 tune from Manuel as well. Just wondering if you ever figured it out, and what the issue was. Thanks!
 

05stroker

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It’s back!!!

And it brought a p690 code with it. Out of the blue only the car intermittently breaks up this time.

Last time I had this issue it just went away after driving some, now the car is actually going lean and breaking up.

FP is good, relay power and grounds check out in the garage.

If I clear the codes ( p0689 and p0690) I turn the key the codes come right back without even starting the car.

Car will start and run though.

Any ideas?
 

05stroker

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Looks like I have a bad connection at F6 C1035B.

Strange thing to note is, I did not have a fuse in the F45 slot this whole time. I did however have one in F39 that shows to not be used until 2007.

I also just noticed how I worked around the clutch switch, I connected B9 to E10 on connector C1035B.
 

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