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2007 Hyundai Santa Fe 2.7L P0741

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30 Sep 2019 15:13 - 30 Sep 2019 15:17 #33941 by radau
2007 Hyundai Santa Fe 2.7L P0741 was created by radau
Hi all,

Diagnosing an issue with a Santa Fe with an automatic transmission using a Snapon Modis, code P0741 is set and you can feel the TCC unlock at highway speeds periodically which makes the vehicle feel as if it's slightly misfiring while it unlocks then locks again. You can see in the second attachment a gap where the TCC disengages to 0% then re-engages after a brief period.

First attachment shows the duty cycle with a probe on the TCC solenoid wire (#9), voltage is read from the 12V supply (#6) on the same harness which is used for L/R & TCC solenoids.

Is there any more testing to be done here or should I move forward with replacing the solenoid? I ran across another forum post where the user had a similar pattern and suspected the solenoid. I tried to engage the solenoid with the Modis but my personality key is bad so waiting for a new one in the mail before trying that, I'm suspecting that I would hear an erratic noise from the solenoid based on the graph cutting in and out rapidly.

Pattern remains the same whenever the TCC solenoid is engaged (2nd gear, 3rd gear, and OD at highway speeds).

TCC Duty cycle averages around 45%, looks like it tops out at 90% then shuts off so it's averaging.

Thanks!

EDIT: Looks like my attachments aren't loading properly, just in case

attachment 1: i.imgur.com/zf3Tkh0.jpg
attachment 2: i.imgur.com/QZxVcqp.jpg
harness pinout: i.imgur.com/jicOWvJ.jpg
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Last edit: 30 Sep 2019 15:17 by radau. Reason: Add attachment

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30 Sep 2019 19:09 #33945 by Tyler
Replied by Tyler on topic 2007 Hyundai Santa Fe 2.7L P0741
Hey radau! For what it's worth, I don't believe you're looking at a solenoid issue. The fact that you can feel the TCC unlock at highway speeds makes me think that you're dealing with a hydraulic or mechanical issue and not an electrical one.

IMO, the best way to rule out a solenoid problem would be to manually energize the solenoid with a jumper wire with an amp clamp around the solenoid power feed wire (pin #6). Besides being able to listen for the solenoid to *click*, you'll also be able to see the pintle movement in the current waveform. AND with application of ohms law, you'll also be able to prove good current draw.

Here's an example of this test on a Toyota with a transmission problem. The solenoid resistance specification was 5.5 ohms.



The Guided Component Test in my Modis says the solenoid should measure 2.7 to 3.4 ohms. Measuring that would be fine and all, but doing the math shows you should see that solenoid draw around four amps. Because it's a lower resistance solenoid, don't leave the jumper in forever. ;) Just long enough to get the waveform.

If you don't have an amp clamp available, the jumper wire test can still be useful, especially since bidirectional testing isn't an option at the moment. If you hear a solid click out of the transmission pan when you apply the jumper, then you can be reasonably confident the solenoid is moving.
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01 Oct 2019 01:03 #33956 by radau
Replied by radau on topic 2007 Hyundai Santa Fe 2.7L P0741
Thanks Tyler!

I think I read something about the PCM commanding the solenoid off if it does not reliably engage but not 100% positive (if even for this vehicle). The cycling does happen though not very frequently, we had it happen 3 times after we initially hit highway speed, sometimes it won't happen for weeks so I was initially thinking there may be a clog in the valve body or an actual slip. Would a slipping torque converter cause this waveform as well or do you think it would be something else?

The vehicle is a family members so I won't be able to check back up on it for a little bit until I go visit but will definitely try the jumper as well as trying to command it on with the Modis.

We did ohm Pin 6 to the TCC wire and got 2.7 ohms.

Will definitely try that out next time I'm down, if it is the solenoid causing that jitter in the waveform would I hear a rapid clicking rather than a solid click?

Thanks again!

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