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Subaru P2762

Diagnose and fix Subaru P2762

A Subaru P2762 is a pretty common trouble code and is defined as: P2762 Torque converter lock-up duty solenoid circuit (Low). Now before you do anything stupid, like jumping to the conclusion that you need a new torque converter or a new lock-up duty solenoid, let’s look at what’s going on here. In many cases, the Subaru P2762 is also accompanied by a P0700, C0057 and a C0045 trouble code. As far as physical symptoms, you may feel a stall when decelerating and a jerk when driving.

What is torque converter lock-up?

The best way to understand how a torque converter works is to take two table fans and aim them at each other. Turn on one fan and the wind velocity will spin the second fan. A torque converter also contains a two fan-like structures. One is connected to the torque converter case which is bolted to the engine’s flywheel (referred to as a “flexplate”). The second fan is connected to the input shaft of the transmission. Instead of one fan blowing air at the other, the fan in torque converter lock upa torque converter blows transmission fluid. A torque converter takes the place of a flywheel, clutch disc and pressure plate in a manual transmission vehicle. The torque converter allows the engine to continue running at idle without killing the engine. In other words, at idle RPMs, the transmission fluid just “churns” between the two fan blades.

When driving, the torque converter acts just like a normal clutch where engine RPMs transfer to the transmission input shaft. But there’s one problem with this setup, energy loss. In a typical clutch system, one engine RPM equals one RPM of the transmission input shaft. But due to the fact that the torque converter is blowing transmission fluid, some energy is lost in the process. To combat that energy loss, car makers modify the torque converter with a clutch arrangement inside the converter that mechanically locks the two fans together. This provides a 1:1 transfer of power from the engine to the transmission.

The lock-up solenoid receives a “duty cycle” command from the transmission control module (TCM computer) to open and close the oil passage to allow or disallow pressurized transmission fluid into the clutch mechanism. The duty cycle ranges from 0% oil flow to 100% oil flow for full clutch engagement.

What does the Subaru P2762 trouble code mean?

Subaru has published a check list of things to measure to see why the code has set, which can range from a shorted solenoid, to high internal resistance or a bad solenoid ground. Here are the tests set forth by Subaru:

1)      IGN off. Disconnect the TCM and transmission electrical connectors and measure the resistance between the TCM connector cavity B54 #26 chassis ground. Resistance should be at least 1Ω. If you don’t see that reading, you have a short in the harness.

2)      Next check the resistance between the transmission connector T4 #2 and the transmission body. Resistance should be 13Ω when the engine is cold.

3)      Check the harness inside the transmission.

In some cases, the fix is to replace the harness.

Bad solenoid is most common cause of P2762

Unfortuantely, the lock-up solenoid is built into the transmission valve body. The solenoid is NOT available as a separate part. So you’ll have to replace the entire valve body. Subaru techs are finding that the real problem is often caused by a bad transmission valve body. Consult a Subaru specialist before replacing any transmission parts if you encounter a P2762 trouble code

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