My 1998 Legacy Outback is showing a p0740 code, the check engine light will come on for around four start cycles then goes back off. Comes back on again after a few more start cycles any ideas

http://www.obd-codes.com/p0740

The code is related tot he torque converter lock-up solenoid.

Possibly the wiring for the TCC solenoid inside the trans is chafed or pinched and is shorting. Very little clearance between the pan and the valve body and there are several wires and solenoids in there that can be damaged if something pushes against the pan.

 

I would unplug the large connector for the trans wire harness up by the firewall and check for corrosion there first. Then check the harness where it runs down the side of the trans for chafed wires. If that's clean the pan will probably need to be dropped to check the wiring inside the trans.

Edited July 23, 201411 yr by Fairtax4me

is the oil pan on the trans dented??????

doesnt look dented and is now not shifting to overdrive. someone told me to check the tps sensor dont see how that would do anything never know though

changed the tps sensor and the light went out and shifted into overdrive again. light hasnt came back on but stopped shifting into overdrive again could there be a code stored in the computer?

Possibly a fault with the TCC solenoid in the trans. I still think you need to pull the pan.

You won't get circuit fault codes for the lockup solenoid because of the TPS.

just seemed funny changed the tps the light went out and was shifting again. hasnt came back on since usually comes back on within a few starts

Edited July 26, 201411 yr by gunther4272001

the trans started shifting again but does it intermittingly will shift fine for short times then stops. Transmission guy said sounds like a wiring problem any ideas where to start at