PS Error - Power steering problem

It takes five posts and you can begin to attach stuff.

Typically power steering failures have been torque sensors getting erratic leading to oscillations. This sounds different.

I'm wondering if maybe a wheel bearing?

You might consider pulling the power steering fuse which reverts to manual steering. This would take out the power steering electronics and allow ruling out a wheel bearing.

Fortunately, the electronic steering ECU is easily accessible behind the glove compartment. But the power steering motor and gears are a single unit.

Bob Wilson

 

There are three fuses and one relay:

• 50A EMPS (engine compartment) - this is probably the fuse that powers the steering motor
• 7.5A ECU B (cabin by driver's knee) - powers the relay that enables the 50A EMPS circuit
• 5A ECU-IG (cabin by driver's knee) - powers the control electronics
• EMPS RELAY (50A engine compartment)- enables the 50A circuit to the control module

Open the hood and facing the engine on the left side is the "Engine Room R/B No. 3" fuse box. Open it up and you'll find:

• 50A EMPS fuse
• EMPS Relay (50A circuit)

In the cabin, the fuse block to the left of the driver's knee, "Instrument Panel J/B" has the smaller:

• 7.5A ECU B - powers the relay that enables the 50A EMPS circuit
• 5A ECU-IG - powers the control electronics

It sounds like you might have pulled the '5A ECU-IG' fuse which would have left the 50A power circuit enabled. If so, it does suggest a failed ECU but I'd pull any of the 50A controlling fuses or better still, the 50A relay to confirm the growling goes away.

Replacing the ECU should be fairly straight forward. Check the messages as I think someone posted a photo of the ECU located behind the glove box. But I have yet to see any online 'step-by-step' replacement guide outside of the Toyota TIS service. If you go for the paper manuals, Vol. 2 has the repair procedures. However, if you examine the unit you can probably 'noodle it out.'

Hummm, take photos and make the online version?

Bob Wilson

 

Ok, this confirms the absence of power from the ECU to the steering motor. That it became hard to steer confirms it. But with the growling remaining, I would suspect a bearing and/or CVT problem. This typically is speed related and tends to be louder when turning one direction or the other.

If the car is stationary in "P" and "Ready", do you get the noise if the wheel is turned one way or the other? This would suggest the EMPS. With a friend turning the wheel, you could get on the ground near the front and isolate the source.

I was able to open the MP4 and hear the growling in iMovie.

Once you take the glove compartment out, you should see the EMPS controller with the connectors facing. You could remove all of the connectors, taking the EMPS ECU out, and confirm the growling has gone away. But the fuse test should have shown the same result.

Bob Wilson

 

No, unless your car has a power steering problem plus a halfshaft or bearing problem.