Help with CODE P1718 - Ford Mustang Forum
 
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post #1 of 10 (permalink) Old 3 Weeks Ago Thread Starter
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Help with CODE P1718

I wonder if my problem that still doesn't go away has anything to do with my transmission. It's been three years and the car still acting stupid, every time the weather or temperature goes over 50's the car vibrates, loses power. No codes or pending codes related to the engine.
The only codes I have so far:

12/18 P0712 - P0136 and after a year:
11/19 Code P1718 This code doesn't have too much info on Google. It seems that is something related to wiring.

Thanks again!

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post #2 of 10 (permalink) Old 3 Weeks Ago
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IMHO, basically you need to check for continuity within that harness.....on one of the pins/leads the signal/power/ground is not going through at some point.


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post #3 of 10 (permalink) Old 3 Weeks Ago
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What is the transmission fluid temperature sensor (TFT) reading? In general it will take an ODB2 scanner capable of reading more than generic ODB2 data. IMO this is the first step to trouble shoot. You don't know if the TFT sensor is:
  • Open
  • Shorted (to ground or power)
  • unstable. This indicates a loose connection.
  • or simply out of range.

The Ford service manual calls out Pinpoint test "B" that basically starts out by see IF the TFT is sending anything at all. Then next it goes on to voltage and ground measurements that are designed to narrow down IF this is a wiring issue or sensor issue. IE confirming there is voltage at the TFT supply and seeing if the TFT's resistance matches a reasonable value depending upon the current temperature.

IMO it's silly to attempt to replace the TFT without determining IF the sensor is bad before hand. Plus the TFT sensor is part of the transmission harness which will require the whole internal transmission harness to be replaced.

Transmission Fluid Temperature C F Resistance (Ohms)
-40 to -20 -40 to -4 967K - 284K
-19 to -1 -3 - 31 284K - 100K
0 - 20 32 - 68 100K - 37K
21 - 40 69 - 104 37K - 16K
41 - 70 105 - 158 16K - 5K
71 - 90 159 - 194 5K - 2.7K
91 - 110 195 - 230 2.7K - 1.5K
111 - 130 231 - 266 1.5K - 0.8K
131 - 150 267 - 302 0.8K - 0.54K

2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.

Last edited by wmburns; 3 Weeks Ago at 04:55 PM.
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post #4 of 10 (permalink) Old 3 Weeks Ago Thread Starter
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Quote:
Originally Posted by wmburns View Post
What is the transmission fluid temperature sensor (TFT) reading? In general it will take an ODB2 scanner capable of reading more than generic ODB2 data. IMO this is the first step to trouble shoot. You don't know if the TFT sensor is:
  • Open
  • Shorted (to ground or power)
  • unstable. This indicates a loose connection.
  • or simply out of range.

The Ford service manual calls out Pinpoint test "B" that basically starts out by see IF the TFT is sending anything at all. Then next it goes on to voltage and ground measurements that are designed to narrow down IF this is a wiring issue or sensor issue. IE confirming there is voltage at the TFT supply and seeing if the TFT's resistance matches a reasonable value depending upon the current temperature.

IMO it's silly to attempt to replace the TFT without determining IF the sensor is bad before hand. Plus the TFT sensor is part of the transmission harness which will require the whole internal transmission harness to be replaced.

Transmission Fluid Temperature C F Resistance (Ohms)
-40 to -20 -40 to -4 967K - 284K
-19 to -1 -3 - 31 284K - 100K
0 - 20 32 - 68 100K - 37K
21 - 40 69 - 104 37K - 16K
41 - 70 105 - 158 16K - 5K
71 - 90 159 - 194 5K - 2.7K
91 - 110 195 - 230 2.7K - 1.5K
111 - 130 231 - 266 1.5K - 0.8K
131 - 150 267 - 302 0.8K - 0.54K
OK I see. Well this is my second transmission. My first summer I thought the car was going through some sort of limp mode because it felt heavy and slow. The transmission got replaced but nothing changed. As I indicated in my opening thread I had a code at the end of the year 2018 and the codes never came back. It's been almost a year and I had the code P1718. So at this point I think my car has wiring issues. The question is...is this faulty wiring can be the culprit of these symptoms since I got this car? How the car is so sensitive to temperature changes?
I took the car to a transmission specialist because I had some vibrations but the mechanic just blamed the universal joint and the tranny mount (which eliminate all the vibrations in the car) The issue about the power loss on temperatures over 50's still continues.
BTW The tranny fluid is a bit darker.


Again thanks so much and I will look for a transmission specialist.
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post #5 of 10 (permalink) Old 3 Weeks Ago
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Test and or replace the trans temp sensor. If you don’t test but replace the sensor and it doesn’t fix it, it’s probably in the wiring. I think those are your options.
*Edit*
Burns, is the TFT integral to the wiring harness? Or is there an actual sensor like an ECT sensor?
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post #6 of 10 (permalink) Old 2 Weeks Ago Thread Starter
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Quote:
Originally Posted by 90lxwhite View Post
Test and or replace the <acronym title="transmission">trans</acronym> temp sensor. If you dont test but replace the sensor and it doesnt fix it, its probably in the wiring. I think those are your options.
*Edit*
Burns, is the TFT integral to the wiring harness? That is a good question!

Or is there an actual sensor like an ECT sensor?
This is my second transmission and replacing the tranny didn't resolve anything so I think replacing the sensor it won't fix. The wiring harness might be the issue since I got two codes related to TFT. The code P0712 (low input-The symptom of this code is limp mode) was set back in December 2018, it was reset and it hasn't come back. A new code has appear which is P1718 which indicates wiring issues, corroded pins, etc or no communication with PCM.
Either way I think I'm close to fix my car. I just need to find a good mechanic who wants to listen and do the right thing.

I'll keep everybody posted.

Thanks
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post #7 of 10 (permalink) Old 2 Weeks Ago
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Where’s the sensor?
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post #8 of 10 (permalink) Old 2 Weeks Ago Thread Starter
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Originally Posted by 90lxwhite View Post
Wheres the sensor?
The temperature sensor is located inside the pan, looks like a very small black rectangle. I found it doing a Google search for the 4R70W and not under Mustang 2000 GT tranny.

I wonder if the sensor is the problem or the external wiring harness that connects to the PCM and O2's? Like I said this is my second transmission and replacing didn't resolve anything.
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post #9 of 10 (permalink) Old 1 Week Ago Thread Starter
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As usual these "gurus" don't want to make sense of the codes and they don't want to look at the car either. Anybody can recommend a transmission forum?

Thanks
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Quote:
Originally Posted by Blacksunshinee View Post
As usual these "gurus" don't want to make sense of the codes and they don't want to look at the car either. Anybody can recommend a transmission forum?

Thanks
http://www.clickclickracing.com/forums/forum.php?
The gurus don’t want to take the job because they can make more money replacing parts vs spending hours diagnosing. The wage the shop pays the mechanic comes into play. They don’t want him/her spending too much time on one job.

Last edited by 90lxwhite; 6 Days Ago at 10:53 PM.
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