How to clear Oil Maintenance Required via OBD / Bad Trip A Button

Problem: 2010 Prius III - Trip / Disp buttons on the steering wheel are not working.

* All other buttons work fine.

* The combination meter is currently in the ODO mode and shows "Oil Maintenance Required".
Since I cannot change to Trip A Mode... I cannot clear the maintenance message.

OBD Questions:

Is there a way to clear the "Oil Maintenance Required" message via OBD ?
Is there a way to change from ODO to Trip A/B via OBD ?

Resources:

I have access to OBD via a ELM327 Bluetooth and a MVCI USB adapter.

I have Techsteam v9.10.037 but do not see a way to clear "Oil Maintenance Required" or change Combination Meter from ODO to Trip A/B.

I've enclosed a PDF of the schematic pages of the Steering Wheel Pad circuit.


Root Cause of the the Problem:

Back to the source of the issue... Techsteam reports error "B1504 Lost Communication with Steering SW"

Looking at the schematics (page 91 of 466) it appears the problem may be a communications issue between the Steering Wheel Pad Switch CPU to Combination meter.

Signal Path seems to be:
Steering Pad CPU board – Wired to Connector z9 pin 7 to Spiral Cable Connector L52 pin 3 to Combination meter Connector L27 pin 29.

A problem with the TX1 line seems to make sense since the other buttons work.

The other steering wheel buttons (AC Mode, Temp +/-, Audio Mode Volume +/- Channel +/- ) seem to work on analog signals based on a voltage divider arrangement without the help of the Steering Pad CPU.

I’ve read that the Gen II models had problems with the steering wheel spiral cable but I also know that the other buttons travel through this cable. I guess it could be a problem where the other lines are fine and only the TX1 line is bad.

Summary Questions:

Any input on gaining access to and what to look for on this signal (Steering Pad CPU TX1 / Combination Meter STRG) ? What voltage measurements should I expect?

Is there a way to clear the "Oil Maintenance Required" message or change from ODO to Trip A/B via OBD ?

Any help and suggestions are very much appreciated... I recently became a Prius Fan and am trying to get up to speed. The Oil Maintenance Message is blocking the Combination Meter display and driving me nuts.

Thanks in advance.

 

The Temp and Air Inlet buttons work... but that's because the Temp and Air Control Buttons use the discrete analog line AC1 (not the TX1 line.)

The problem was indeed the spiral cable. The IG (12v power) line was open due to the open in the clock spring line.

The mechanics worked out where there was another nearby 12v line that lights the button lights. I added a diode to the steering wheel control board so it now gets 12v when the lights are on. Now everything works as expected. (Except I have to turn the lights on if I need to change the Trip/Display mode... which is not very often).

I'm not original owner... so it was a quite a shock to see the info displays for the first time. The voltmeter almost jumped out of my hand and it was such a cool surprise to see the "Touch Tracer Display" popups for the first time.

I wonder how many Gen III Prius owners have or will have the failing clock spring (as was the case with the Gen II owners)?
And I wonder if Toyota will do a recall on this generation's failures?

 

Its been quite awhile since I did that mod... I'll check some more but I was not able to find any pictures (if I made any at the time).
Here's my best attempt from memory...

I'd recommend you first determine which lines you have open. You can do that by checking the wiring connection points on either side of the clock spring. The reason I was able to fix mine may be unique to my specific failure (with the open IG line). Does your left side buttons work and only the Trip / Disp buttons are at fault?

If you happen to have the same problem I had... You have to remove the steering wheel, then the steering wheel pad control boards. The boards contain the buttons and the wiring connectors. Once you get to that level you will need to use a voltmeter to find what lines are open.

The power source I used was sourced from the "Z9" connector", signal "IL+2". This IL+2 line provides 12v to the LED's under the steering pad buttons when the headlights are enabled. Since the LEDs are only active when the lights are on... I have to turn on the running or head lights for the right hand (problem) buttons to operate.

The + side (anode) of the diode was soldered to the IL+2 line and the - side (cathode) of the diode was soldered to the (broken) IG line.
I soldered the diode to the steering pad pc board. I used a small glass signalling diode, nothing special such as a 1N4148.

The diode is probably not needed but I added it as an additional buffer to the equation (mainly because I did not have the full schematic at the time). It's been working fine with no further issues since 2015. Not ideal but since I did not use these buttons often it made sense at the time (especially since a new clock spring was so expensive and the 2nd generation had reoccurring issues).

Since the clock springs are now readily available at reasonable prices you may want to replace the bad one once you verify it is the root cause.

Hope this helps.