OBDII Port Problem

Due to a recent decrease in fuel economy, I connected my scan tool to look for any pending codes, possibly for the O2 sensors. Instead of any information, my scan tool gives me a "Link Error". I tried disconnecting and reconnecting multiple times with no luck. Thinking it was my scan tool (which works on other vehicles I tested), I borrowed a friend's scan tool...which is giving me the same communication error issue. Now I suspect a problem with the port itself (or, hopefully not, the ECU itself). I searched the forum and came up with this thread:

http://www.tacomaworld.com/forum/2nd-gen-tacomas/240244-obdii-not-communicating-scan-tool.html

No positive diagnosis was ever found in that thread, which is why I'm making a new one. Does anyone have any ideas? I quick visual inspection of the port shows that all pins are present and don't appear to be deformed.

 

Anyone?

 

Here is a link .
http://alflash.com.ua/OBDII/ReadNew.htm

Edit : better link here
http://www.obdtester.com/obd2_protocols
Find out what pin on the OBD2 connector supplies voltage to your scanner .
Do you have 12 volts to that pin with the key turned on ?
Do you have a digital volt ohm meter ?

 

Best link I could find
http://pinoutsguide.com/CarElectronics/Toyota_lexus_obd2_diagnostic_pinout.shtml

 

Have you ever used that scan tool on your truck before? If so and it did work you might try disconnecting the battery for 10 mins or so and see if that helps? Just a thought. I'm sure someone on here will know much more about it.

 

I know the power pin is getting power because the scanner turns on when connected and it loads its software. The problem comes when I tell the scanner to check for codes. At that point it tries to link, then says there is a communication failure/error.

Also, I know it's not the scanner because both scanners (mine and the borrowed) work on every other vehicle I've tried it on.

 

Sounds like you narrowed the problem down then.

 

Only a little. It could be a pin socket slightly bent and not making contact with the scanner plug, it could be a wiring issue not getting the proper signal voltage to one of the many communication pins, and it could be a failing ECU.

 

Pins 4 (CGND, Chassis Ground ) and 5 ( SGND, Signal Ground ) are grounds.
Pins 6 high and 14 low are the Can Bus signal wires.
Pin 16 is the power 12 volts.

That is all that is needed for OBD II Can Bus.

Looks like you have an issue with wires ( pins ) # 6 and 14 or the ECU.

 

are both scanners canbus capable?

 

You have 12 volts to power the scanner through pin 16
Now you have to check for 5 volt signal reference from the ecm ?
Do you have a digital volt ohm meter ?

 

In a Gen 2 Taco ther eis an ODB fuse under the hood and they pop all the time for some reason, replace the fuse = fixed.