Transmission speed sensor, code PO731

1998 DODGE CARAVAN

199,000 MILES • 3.3L • 6 CYL • 2WD • AUTOMATIC

MICHAEL MCCORMICK

MEMBER
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Recently had to remove the sensor plugs off the transmission, forgot one and van went into limp mode. Connected the plug and it would not turn over, could not figure it out so I removed the plug off output speed sensor and it started right up and threw a PO731. It all started with replacement of the radiator..

Sep 15, 2018 at 5:26 PM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

Hi and thanks for using 2CarPros.com.

That is an interesting one. That code, indicates a problem with the the RPM signal vs the vehicle speed in first gear. Honestly, I cannot see how that is related to a no start. Tell me, when it would not start, did the starter engage? Also, if you clear the code and reconnect the sensor, is there any difference?

One last idea, if your scanner has freeze frame data, check to see what the conditions were when the code was set and let me know.

Thanks,
Joe

Sep 15, 2018 at 9:08 PM

MICHAEL MCCORMICK

MEMBER
10 POSTS

Thanks for response! It threw four codes total POs : 403, 500, 700, and 731. I had power to the relays " heard the click," everything else had juice, just would not crank. No I did not clear the codes but that will be the first thing I do. I have a cheap scanner no freeze frame. Let me try your way, I hope it works. I will keep you posted!

Sep 16, 2018 at 10:58 AM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

Hi again. The other codes are interesting. One is a no signal from the speed sensor (which makes sense) the other is for the EGR. Again, although an EGR issue can cause a no start under certain conditions, it is not related to the transmission.

The P0700 deals with the ETAX relay. It is controlled by the transmission control module (TCM). It supplies power to the transmission solenoid pack. Again, it should not have caused a no start.

Let me know.

Joe

Sep 16, 2018 at 7:16 PM