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PNP Sensor Replacement

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Old 12-22-09, 10:33 PM   #1
LuvMyRX01
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Default PNP Sensor Replacement

Hi. I've been getting the ESC & CEL lights for a few weeks now, and the code is P1780 - PNP Switch Malfunction.

How do I know if its the PNP sensor or PNP switch that has failed? (or are they the same thing?)

Wondering if anyone has replaced a PNP sensor and can advise me how easy or difficult this is. I don't have the manual so would appreciate the steps if anyone has them.

Thanks.
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Old 12-23-09, 07:49 AM   #2
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Okay,I`ll bite. What the H ell is a PNP sensor?

Do you mean this? > Park/Neutral Position Switch Malfunction (Only For A/T)
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Old 12-23-09, 09:16 PM   #3
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It's a bit complicated to diagnose. Have you tried to clear this code or examine the PNP firsthand on the front of the transmission?
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Old 12-25-09, 03:41 PM   #4
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Lexus114 - Yep that's it. The Park Neutral Position switch/sensor.

Lexmex - I cleared it once, and crawled around and tried to get a look at it. I was able to disconnect and reconnect the electrial connection. There's nothing obvious that's wrong with it. When I drove it again the lights went back on after a few hours. How do they diagnose it in the shop?

thanks.
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Old 12-25-09, 08:25 PM   #5
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Quote:
Originally Posted by LuvMyRX01 View Post
Lexus114 - Yep that's it. The Park Neutral Position switch/sensor.

Lexmex - I cleared it once, and crawled around and tried to get a look at it. I was able to disconnect and reconnect the electrial connection. There's nothing obvious that's wrong with it. When I drove it again the lights went back on after a few hours. How do they diagnose it in the shop?

thanks.
Have you tried starting it in D as opposed to P or N? (that's the mechanical check there).

I played with this device once the last time I had my transmission out of the vehicle 2 years ago (it's on the front of the tranny and has a very strong insulated cable attached to it). It's almost always electrical in nature when this occurred and rarely mechanical (you would have issues that would be immediately noticeable on the mechanical side, and this device is just not as picky as some of the other parts on this vehicle).

The short of this is it inevitably requires testing the electrical connections and responsible. I don't have the values offhand (I'm out of town for next day or so), but when I get back I'll post them here. Lexus/Toyota would use their own handheld diagnostic scanner for this.
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Old 01-13-10, 05:03 PM   #6
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Lexmex,
I did check the switch by trying to start it in Drive, and it would not start, so assume that the PNP sensor is the problem. Can you give me the readings for testing the sensor and any hints on how to take it off?

thanks!
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Old 01-13-10, 08:25 PM   #7
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Originally Posted by LuvMyRX01 View Post
Lexmex,
I did check the switch by trying to start it in Drive, and it would not start, so assume that the PNP sensor is the problem. Can you give me the readings for testing the sensor and any hints on how to take it off?

thanks!
It's going to be a bit complicated to do, I sent you a PM.
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Old 12-03-12, 03:49 PM   #8
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Lexmex,
I had been having the CEL with code P1780. I had replaced the switch but still getting the same code. The car seems to be driven fine. What could be the cause?
Thank you.
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Old 12-04-12, 10:15 AM   #9
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Lexmex,
I had been having the CEL with code P1780. I had replaced the switch but still getting the same code. The car seems to be driven fine. What could be the cause?
Thank you.
Welcome to the Club.

Not sure how much help I can be here. The P1780 is directly related of course to the park/neutral switch (only other issue can be the Engine Control Module, but doubtful). Last time I played with this was about 5 years ago in Mexico and we had the battery disconnected when reinstalling it on the tranny after some work to it. I remember checking that I could only start the vehicle in Park or Neutral and was very careful about the torques on the particular bolts (had been warned that this part can get fidgety at times by my uncle on other vehicles). The only other way to diagnose this is with Lexus/Toyota hand held tester (and that means a trip to somewhere with one).

Are you clearing the code and then seeing it reappear after a certain amount of time?
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Old 12-04-12, 10:28 AM   #10
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Becareful of the adjustment of that switch assembly....
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Old 12-04-12, 01:27 PM   #11
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Originally Posted by Lexmex View Post
Welcome to the Club.

Not sure how much help I can be here. The P1780 is directly related of course to the park/neutral switch (only other issue can be the Engine Control Module, but doubtful). Last time I played with this was about 5 years ago in Mexico and we had the battery disconnected when reinstalling it on the tranny after some work to it. I remember checking that I could only start the vehicle in Park or Neutral and was very careful about the torques on the particular bolts (had been warned that this part can get fidgety at times by my uncle on other vehicles). The only other way to diagnose this is with Lexus/Toyota hand held tester (and that means a trip to somewhere with one).

Are you clearing the code and then seeing it reappear after a certain amount of time?
Yes, I had cleared the code and then it appears after driving it for 5-10min at >35MPH. I had also sent the ECM to a company in Tennessee for rebuild but it did not fix it. I guess I should take it to some garage that has the hh tester for diagnose.
Thanks or your help.
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Old 12-05-12, 06:55 AM   #12
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Originally Posted by Tai2001RX View Post
Yes, I had cleared the code and then it appears after driving it for 5-10min at >35MPH. I had also sent the ECM to a company in Tennessee for rebuild but it did not fix it. I guess I should take it to some garage that has the hh tester for diagnose.
Thanks or your help.
I alluded to this an in an older post, but the code is inevitably electrical. What happens with these things is that occasionally people will put the bolts on it, it gets loose and then a code winds up happening (that's the fidgety part that shouldn't happen, but did most of the time my uncle saw that issue). As long as the thing is on there tight enough, shouldn't be an issue.
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Old 12-05-12, 07:08 AM   #13
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Originally Posted by Lexmex View Post
I alluded to this an in an older post, but the code is inevitably electrical. What happens with these things is that occasionally people will put the bolts on it, it gets loose and then a code winds up happening (that's the fidgety part that shouldn't happen, but did most of the time my uncle saw that issue). As long as the thing is on there tight enough, shouldn't be an issue.
Thanks Lexmex. I will take it back to the person who replaced the part and ask him to re-tighten the bolts. If we cannot fix it, I plan to take it to Clear Choice garage here in Houston.
Thanks again.
-Tai
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