PO731 code

[bdecriscio]

Hi folks , 1999 outback , 2.5 ,95000 miles , automatic. I had many problems in the last year with the mystry transmission problem . finaly solved by finding loose wires in the resistor that had gone unchecked internally. In the meantime, the tranny was rebuilt, everything internally except the torque converter. It ran fine for about 5 weeks then started flashing the AT temp light and slaming into second gear and not upshifting to third. The first two times this happenened I was not able to get back to the repair shop before it started working properly on it's own.(All I did was shut it off and restart it) The third time I was able to get the trouble code read but by the time we reviewed what it was etc. the car was running fine again before he could road test it with the scan tool on. One additional note, after the first two occasions, there were no codes stored. Before the problems started happening, I have had intermintent check engine light for a bad knock sensor. Now it's been three days at the shop and it is running fine so I'm hoping someone can help with somewhere to go. The scan tool suggests some options such as the throttle posistion sensor or speed sensor but the speedometr works ok and the normal running between events has me a little confused. Bye the way, the code 731 indicates first gear ratio incorrect . Sorry for the long post, thanks, Bob

[Legacy777]

Hi Bob,

 

The problem is intermittent, and sounds like a short or possibly a pinched wire. What I'd probably try and do is trace all the wiring back from the TCU to the transmission connector and verify continuity, and then check the transmission wiring/components to see if their resistance measures up with what they should be.

 

While you're checking wire resistance, I'd suggest pulling/moving the wiring harness around to see if that gives you an intermittent loss of continuity.

[bdecriscio]

Hi Bob,

 

The problem is intermittent, and sounds like a short or possibly a pinched wire. What I'd probably try and do is trace all the wiring back from the TCU to the transmission connector and verify continuity, and then check the transmission wiring/components to see if their resistance measures up with what they should be.

 

While you're checking wire resistance, I'd suggest pulling/moving the wiring harness around to see if that gives you an intermittent loss of continuity.

 

Thanks for the reply, I'll start there, as an update, today it happened again after two good days, a few restarts and it ran fine for awhile,then started hard shifting without any flashing of the AT-Temp light. Thanks again, Bob