Cannot Read Diagnostic codes

[Mohammedpatel086]

Hi guys, 

I have a 2003 Toyota corolla diesel 2.0 d4d e12 3dr. (Pre-facelift) @ 200514miles

Now i believe in the UK the OBD2 standard was across the board in diesels came around 2004/05. ( correct me if i am wrong) 

But some companies started using it before it was the standard like VW. 

My 1st question is would an OBD2 scanner work with my car or not. 

2nd is if it is supposed to work, is there a solution to "cannot communicate to the vehicle".

I believe the unit is getting power because the check engine light comes on when the device is plugged in.  some of the devices tried get the engine size. But in the end all of the devices i have tried end up with "cannot communicate with vehicle"

OBD2 Readers tried are: 

Delphi diagnostics

Elm obd bluetooth reader

Generic eBay one ( tested on friends 1.4 corolla 06 which worked) 

I understand this issue could be due to a bad ground fault at one of the sensors but please could someone shed some light on this as i need to check why my check engine light is on. (This ties in with my other post) 

[oldcodger]

Hi,

According to the Haynes manual, petrol and diesel  2002 -2006 models have OBD2 connectors.

I have one of these old style readers and it works fine on mine, are all the ones you used the modern bluetooth or usb types ?

You could ask a local garage or places like Halfords , to try their scanners , usually for a small fee, cheaper than buying another scanner.

If they don't work then looks like you have a wiring or ecu fault.

Have you inspected the obd2 socket, both the connecting pins and the wires on the rear ?

 

[DeTomato]

There are some cars which have different OBD2 pin configuration in the car port according to the protocol supported for the model variant. This means the obd2 scan will not initialise and the error "cannot communicate to the vehicle" comes up.

It's usually a matter of finding patch configuration on the port mapped on the computer to trick it into resetting and remapping the connector for the car. I did this once many years back on Windows XP but these days it's cheaper to buy another one.

Check to this see what OBD2 Protocol CANBUS you need for your car model and buy one that will work (the recommended option).

[Mohammedpatel086]

Thanks for the reply. I will do that now

[Mohammedpatel086]

On 6/14/2018 at 6:01 PM, oldcodger said:

Hi,

According to the Haynes manual, petrol and diesel  2002 -2006 models have OBD2 connectors.

I have one of these old style readers and it works fine on mine, are all the ones you used the modern bluetooth or usb types ?

You could ask a local garage or places like halfords , to try their scanners , usually for a small fee, cheaper than buying another scanner.

If they don't work then looks like you have a wiring or ecu fault.

Have you inspected the obd2 socket, both the connecting pins and the wires on the rear ?

 

Wires have been inspected and everything seems sound. But if i cannot figure anything out i will take it to a local garage. Thanks for the reply tho

[DeTomato]

I just found an interesting take on what may be causing the "cannot communicate to the vehicle" error. It is very simple. If you've upgraded to a new Windows O/S like Windows 10 then you need to re-install the OBD2 drivers (and maybe the software too). It then works as expected. Also, don't use ANY updated OBD2 software, rather only use what is supplied with the drivers else it will not work as expected. In other words, go back to your baseline OBD2 software and/or re-install the drivers and then your device will re-communicate with the vehicle!

[KenMavor]

Or try an android phone app like Torque OBD checker as computers are so sensitive to the correct OS, sw and app version.

[DeTomato]

Checked out my VVTL-I with my computer diagnostics today. There were NO error codes, but the fuel/air mixture indicated was it was running lean. Considering this car had been standing for over 5 years that's pretty good I reckon  

I wondered if anyone thinks it is worth cleaning the PCV to see if that may alter it to "less lean"? It's now just done 60,000 miles ONLY so this is due I guess? Otherwise, is it worth checking for air hose leaks and cleaning the MAF sensor to see if the mixture becomes good? It's had new engine air filter already and 5W/30 oil change, and I put some injector cleaner into it (does this make it run lean???)

Any ideas to make it less lean otherwise? Thanks