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supertech
supertech, master tech
Category: Jeep
Satisfied Customers: 2251
Experience:  a1-a8,l1,t2,b5.ASE triple chrysler master tech 42yr experience HEV chrysler Specialist
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Jeep 1999 grand cherokee Code P0720 comes up bad output speed

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Jeep 1999 grand cherokee Code P0720 comes up bad output speed sensor cicuit . went to autozone picked up new one installed and erased code came back with in 30 sec never drove it?????????????? do I have bad sensor from new /bad wire harness / bad pcm help chet also wire diagram would be nice to check harness
Where is the sensor that you replaced located?
Customer: replied 7 years ago.
trans is 45rfe replaced back sensor which is the output erased code 3x it still came back after few secs / then cleaned off the sensor I took out and installed it in the font (input ) sensor same thing cleaned code came back with out drive wonder if it isn't wire or pcm ?????????
Without knowing the exact code number I can't tell you for sure, but if it was a "output sensor circuit" code then the only things that can cause it are a bad sensor, wiring or TCM (transmission control module). You need to check the integrity of the wiring and if it is ok then replace the TCM.
Customer: replied 7 years ago.
exactly what I was saying but I need to know wire diagram so I can trace back to tell if there is a break in the wire between sensor and the pcm / also can I check the sensor to see if it is bad from new is their an ohm reading test DBR code is P0720 output speed sensor circuit
Hi my name is John.

Have you done the test for the code p0720?

Here a copy of the wiring diagram and pin out of the two connectors.

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Let me know what else you need
Customer: replied 7 years ago.
Hi John , the test I saw in the jeep manual called for the use of the miller sp tool 8815 which I don't have access to ,which is why I was looking for the wire diagrams and if you could do ohm test to check the senders .also bit in question why code was showing right back up after it was cleared without driving it . Don't input and output sensors need the jeep to drive to send signal to the pcm by building up electric current
Yes the transmission need to be turning to send a signal.

there is either a short or open in the wiring or a bad connector most likely, would you like to know what else to test for the problem?
Here a copy of the test for you to do.

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Let me know if you need more
supertech, master tech
Category: Jeep
Satisfied Customers: 2251
Experience: a1-a8,l1,t2,b5.ASE triple chrysler master tech 42yr experience HEV chrysler Specialist
supertech and 2 other Jeep Specialists are ready to help you
Customer: replied 7 years ago.
John I wish you lived closer/ where is the trans control relay located and pin conf. /also could i just hook up wire jumper from the output speed sensor plug and unplug tcm check ohms from output side to 14terminal and check grd same way to see if is break in wire ? sorry if I ramble here just getting bit bummed tooth and head are killing me and garage is full of tools can't get in OHAh Chet
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The number will be on the relay itself.

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Customer: replied 7 years ago.
hi john sorry didn't get back to you had health proplems going to try to work on it today or next couple chet
Let me know what you find when you can, hope you feel better.
Customer: replied 7 years ago.
Hi John went back guess I can do it here Thanks Chet

Thank you

 

John