OBDII error - No communication

I took my tacoma to 3 different smog test shops and couldn't pass the test because of an error with the OBDII connection - no communication. The truck passed the actual smog test with flying color. There are no blown fused in the engine compartment or under the dash. The smog tech checked myOBD II post and it has power. I found a thread posted here from 2007, but no one replied to it. Please help if you can. Thanks.

 

Had the same thing happen just the other day. CEL was on and had my buddy check it with his scanner and it came up error. Had another buddy with a snap on modis scanner check it and it read the codes. Try a different scanner.

 

The first smog station tried twice and could not communicate with the vehicle. He wanted $95 to diagnose the problem on top of the $53 for the smog test.

The second smog station (a test only station) ran the test 3 times and he told me, he has the lastest software update for this system. He said my truck is a CAN vehicle and his computer should bypass the OBD interface, but it didn't and failed. Test and service were free!

The third smog station also ran the test 3 times he also used a snap-on scanner which did not established a communicate line, double check the fuses and wires, all checked out ok. Test and service were free!

I just spend 2 hours examining all of the wires and connectors under the dash and found a loose single female pin connector near the gas paddle. It looks used, but I couldn't the corresponding male pin.

 

Have you disconnected your battery recently? Sometimes that communication error may occur if the ECU haven't totally reset. (may take 50+ miles) I would drive it around and then hook a scan tool up to make sure there are no codes before taking it for re-inspection. If not, then recommend another scanner.

 

I took my truck to the dealer and it passed the smog test. The tech said there is nothing wrong with my port. My truck is a CAN vehicle, not an OBDII. Next time I'll just go to the dealer for the test and save me some trouble. Thanks to all who helped me!

 

Don't mean to hijack the thread but I'm having a similar problem, so better to kickstart this one.

06 Tacoma PreRunner, V6 Auto. Never had any problems other than gas cap lost it's seal last year. Tried to get it inspected today (96 and up require emissions testing in NC) and she failed. Reason stated was "could not establish communication." I checked every fuse in both blocks, under the hood and under the dash. Any suggestions before I by a new ECM? Thanks

 

Seems like OP was able to get smog at the toyota dealership, can you do that?

 

I've got another mechanic/inspection station who's willing to test the connection and see what happens. If it fails again I guess the dealership will be next stop

 

CAN is a protocol that is OBDII compliant along with several others. It is like a subcategory.

 

Im having the same issue with my 08' No connection when brought to the inspection station. Next step is taking it to the dealer. Any updates on this? Thanks.

 

Just had the same problem with mine. Three tries with their computer and could not connect. My scan gauge connects right away. Took it to a friend at a shop and could not get their new snap on diagnostic computer to connect. Messed with the connection for twenty min and finally connected. Took the entire obd wire harness and jammed it forward into the connector. This seemed to solve the problem at least for now.

 

Often the "no communication" error has nothing to do with the connector. It is a product of the machine finding the correct protocol and communication parameters in order to communicate with the computer. Not unlike the old baud rate issues some of us old folks fought with computer telephone modems.

 

http://www.tacomaworld.com/forum/2nd-gen-tacomas/334772-odd-obdii-port-problem.html

http://www.tacomaworld.com/forum/2nd-gen-tacomas/312661-obdii-port-problem.html

 

Brought mine to the dealer today for a second attempt at inspection; same issue (could not communicate). The tech checked all the fuses under the hood with a test light (I watched him) with no luck. He also, tried pushing all the pins into the connector to make sure everything was properly seated, this didn't help. So this makes two different shops that are unable to link up with the OBDII. At this point I have scheduled an appointment in a week to have them diagnose the problem, but at $95/hr to start, I was really hoping for some additional advise. I've read all the threads on TacomaWorld pertaining to this issue and no one seems to have a definitive solution besides the fuse (which is functional in my case). Any help would be appreciated. Thanks in advance.

 

what was the outcome?

 

Snap on and every other decent newer obd 2 scanner will work with your truck. You have a problem with your port most likely.

 

Having the same issue at the dealer
2018 tacoma
No communication
connector is getting power
They tried replacing the connecting pins
No luck so far

 

Any luck?

I'm having this exact same issue, and I found some resources that can help. If you measure the resistance between the can pins (6 and 14) you should get just over 60 ohms. If one of the two 120 ohm terminating resistors is disconnected it will read 120 ohms. If both are it'll read in much higher.

If you want to diagnose with an oscope you can, connecting to both the 6 and 14 pins. Here's a site that goes into a bit of detail: https://pmmonline.co.uk/technical/can-bus-fault-finding-tips-and-hints-part-1/

Also, another forum post on here about a mechanic solving a series can communication issue. https://www.tacomaworld.com/threads/can-communication-issue.571362/.

I've tried both of the above with no luck. Am going to reset the ecu tomorrow by disconnecting the battery and then driving around for a bit to see if it solves it.

Wondering if the dealership/shop ever figured yours out??

 

Can you talk to any module on the network?

CAN systems usually aren't terribly hard to troubleshoot if you have a scope, a DVOM, a capable scan tool, and a wiring diagram.
First step typically is to see which modules (if any) will communicate, if you can talk to some but not all you need to diagnose the part of the network that won't talk, if you can't talk to anything then you need to check network resistance and if that's good put a scope on it and look at the signals (should be 2.5v to 3.5v square waves on one line and 2.5v to 1.5v square waves on the other line) and go from there.