On-board Diagnostics

[IanXT4]

Does anyone know exactly how Toyota have implemented their On-Board Diagnostics for a 2004 PETROL 4.2 RAV4.

As far as I can figure out the car has a standard ODBII interface through which standard ODBII engine data can be read, and basic engine codes can be accessed and reset. However, it is not clear to me how an owner can access any other on board systems such as the ABS ECU, Airbag ECU , Climate Control ECU etc.

My other car is a 1999 VW Golf and using the VW ODBII interface (and cheap PC cable) you can connect via a Free PC package called VAG-COM to fetch the ODBII engine data and also communicate with every separate on-board ECU based system (ABS, Transmission, Airbag, Climate etc). This enables you to read live data, interrogate error codes and reset codes/lights when necessary.

(If you go further and license the VAG-COM software you can even "dealer" program each of the ECU's to customise the cars parameters, locking preferences, lighting delays, etc etc)

Does any one know of a similar PC software package for Toyota's, all I can find is basic third party ODBII engine ECU interfaces.

How, for example would you query/reset an ABS or Air Bag fault to remove the warning light on the dash ?

Is it a separate proprietary Toyota interface protocol over the standard ODBII connector, requiring specialised and expensive analysers ?

Many thanks

Ian

[Hoovie]

Hi Ian - to answer the simple part of the question, a device like a Scangauge can scan for error codes, display the code and reset them, and I think this is true of all the codes the Toyota puts out.

A non-proprietry OBDII interface was a legal requirement from around 2001 for petrol cars and 2005 for diesel cars.

I think Anchorman has a device that reads and resets these codes which costed about £30 or so.

What is about to link into a PC not sure specifically myself, but there will be a number of options and I reckon you will get some replies advising you what they are

[IanXT4]

Thanks for the reply Hoovie,

I had a look at the literature for the Scanguage II and as far as I could see it could only access the standard ODBII which is engine information only.

As far as I could see it only mentions in the literature that it can reset the Engine warning light.

My understanding is that ODBII was mandated to ensure that garages could read all engine data for emmission regulation and testing, as far as I can see in its basic form ISO ODBII is does not cover ACCESS to other onboard systems such as ABS or Airbags.

I did find reference somewhere on the internet, that some implementations ? of non proprietory ODBII pass extra error codes from other systems to the engine ECU, but as are as I could see it was for error code display only, there was no way to reset non engine based error codes over a non proprietary ODBII.

All seems very confusing :-)

Ian

[Hoovie]

Oh, I thought they did a lot more! I am sure Anchorman will know a lot more on this topic

[shcm]

Ian,

My understanding is that ODBII was mandated to ensure that garages could read all engine data for emmission regulation and testing, as far as I can see in its basic form ISO ODBII is does not cover ACCESS to other onboard systems such as ABS or Airbags.

I believe your understanding is correct. The protocol to access the other systems is usually proprietary.

All seems very confusing :-)

Indeed, so spare a thought for us ECU suppliers who have to actually implement it :D.

Does any one know of a similar PC software package for Toyota's, all I can find is basic third party ODBII engine ECU interfaces.

How, for example would you query/reset an ABS or Air Bag fault to remove the warning light on the dash ?

Is it a separate proprietary Toyota interface protocol over the standard ODBII connector, requiring specialised and expensive analysers ?

I don't know of a Toyota protocol package, but then I haven't looked that hard. The elm (http://www.elmelectronics.com/) or elm clones (usually not an elm chip, but a small microcontroller, but so what....) OBD only PC interfaces are the most common.

With the 4.3 RAV, you can access and reset, for example, ABS DTCs without a hand held tester. Connecting pins 13 and 4 on the diagnostic connector socket will display DTCs on the instrument pack display. Pressing the brake pedal 8 times within 5 seconds will clear DTCs. Even versions without a display will flash codes via the brake warning light.

As an increasing number of vehicles get instrument packs with displays, it does bring into question why a dedicated tester should be needed at all. Having everything built into the vehicle is far more sensible IMHO. The cynical would say they can't charge you ££££ to read codes and/or change functionality then though..... :D

[IanXT4]

Thanks shcm, very interesting

This whole post came about after my Airbag warning light illuminated on my Golf, I searched a VW forum and found out that for £25 from a reputable supplier (cheap eBay ones were less than £10) I could get an ODBII inteface cable and download a VAG-COM package for my PC.

I could not believe the comprehensive level of diagnostics that were freely available. I connected the PC to the ODBII, requested to speak to the Airbag ECU which informed me "IN ENGLISH" What type of problem I had with the driver side airbag. Quick search in the forum led me to a possible loose connector under the seat. Reset the Airbag ECU, light went out and stayed out. Job done :-)

VW wanted £50 plus VAT for the diagnosis !!

Then I thought it would be prudent to prepare myself for a similar problem with the RAV 4, since I now had a ODBII PC cable all I needed was the equivalent Toyota software, or so I thought :-)

In the age of the internet, I hope I do not have to go rely on shorting pins, counting flashing brake lights and pressing brake peddles X times, its CHEAP but surely there must be a better way.

Thanks

Ian

[anchorman]

You can get them but they are expensive and usually the domain of a jap car specialist or larger independant. This is the one Toyota use;

http://www.efichip.com/index.php?237956877

There are others;

http://toyota.spx.com/pdf/TY04-168.pdf

I've got this one;

http://www.autotec-direct.com/basic-obd2-c...aders-139-c.asp

Then there are mid range ones;

http://www.autotec-direct.com/advanced-han...aders-140-c.asp

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