Emissions test failure - no OBDII communication

[Mark]

I have a '97 Lexus ES300 (131K miles). My Connecticut Emissions test
failed today due to no OBDII communication. The guy said he couldn't
get a reading. He suggested it could be as simple as a blown fuse or
as complex as the computer itself.

I did some search on google and various forums. It was suggested to
check the cigarette lighter as an indicator of a blown fuse. My
cigarette lighter works fine. I use that to charge my cellphone daily.

What other fuse could I look at? Where would be the location of the
fuse? If the fuse is fine, what else do I need to look into?

I would appreciate any help I can get. Thank you in advance!

[Brent]

Could be a bent pin on his code reader too... it seems very odd that a
computer would just stop communicating. You'd probably know it if the
computer had lost power too.

You could try buying your own OBD2 reader or see if someone else's
works, like at auto repair place or parts store.

[Mufazzal Bohri]

On Mar 8, 1:40 pm, Brent <tetraethylleadREMOVET...@yahoo.com> wrote:
> Could be a bent pin on his code reader too... it seems very odd that a
> computer would just stop communicating. You'd probably know it if the
> computer had lost power too.
>
> You could try buying your own OBD2 reader or see if someone else's
> works, like at auto repair place or parts store.

I doubt it was his code reader as another guy just ahead of me
successfully passed the test. I will still borrow a OBDII reader to
see if I get any different results. Assuming I get the same
communication error, what do I need to look into? Thank you.

[Tegger]

Mark <muf...@hotmail.com> wrote in news:9aae5eea-61d6-4e21-ac62-
13ced6...@34g2000pru.googlegroups.com:

Was the tech using a CAN-compliant reader to check your non-CAN system?

--
Tegger

[Mufazzal Bohri]

On Mar 8, 2:47 pm, Tegger <inva...@example.com> wrote:
>
> Was the tech using a CAN-compliant reader to check your non-CAN system?
>
> --

I am not sure about that, but I have been going to the same place for
the past 6+ years. I have not had any issues in my previous 3 tests at
the same place. And it is the same guy I have been seeing since then.

[Bill]

"Mark" wrote in message

You will need to get the factory service manual set of books (would
include electrical diagrams and emissions [computer] book) and follow
the troubleshooting instructions. That set of books typically costs
around $150 as there can be 4 books to the set and 2000 pages total.
Order from dealer for your specific vehicle.

But if there are multiple computers on the vehicle along with computer
local area networks, then troubleshooting might also require the use
of specialized computer diagnostic equipment.

If any do-it-yourself wiring has been done, this could have tapped
into a computer network wire. Try undoing that if this was done.

Also look at the OBD electrical connector and see if there are any
bent pins.

As to fuses, here is testing instructions...
http://www.dinosaurelectronics.com/Test_Fuse.htm

Otherwise I would suggest you take it to a Lexus dealer as they would
have the service documentation and computer testing equipment.

Note: Modern vehicles can have multiple computers and multiple
computer networks. In some cases a computer network may not be working
or one computer may not be working. Not something you could test with
a "multimeter"! Rather you need to connect a computer to a network or
working computer, then with that try "talking" to the other computers
and see what is working and what is not.

If you have just one computer, that makes it easier, but you may need
to transfer a chip or have some programming done if the computer is
replaced. A dealer thing for the programming.

[Mark]

Wow.. believe it or not, it was actually his code reader that was
problematic. I had a new OBDII scanner that I got from amazon a few
months ago. Just for curiosity, I hooked it up and it was able to get
a reading. So I took it back to him and passed the emissions this
time.

I didn't think it was his code reader as I saw 2 guys, before and
after me, pass the emissions while I was there. So somehow his code
reader didn't work only on my car. But today it took just a minute for
him to get a reading and give me a Pass certificate.

Thanks all for your help.

[robdieg...@gmail.com]

I have a very similar issue with my 1997 ES300 Lexus (I'm the original owner). 3 days ago I went to get a smog done but failed because of no OBD signal communication during testing (a first). The car is a low mileage (110) and previously had passed all other smog testing(last passed 2yrs ago). Vehicle gets its routine maintenance fluids/oil/ filters, belts, wipers, brakes, transmission/radiator flush and new battery to name a few but never had any major mechanical repairs or modifications performed on the car. Aside from this current issue the car sounds and runs fine. Never experienced dashboard lights or a check engine light. I have done some online reading a common problem seems to be the cigarette lighter fuse but both of mine work since I use them to charge my cell phone and Ipad on daily basis.

When I get home, plan on doing a visual inspection of the DLC for an bent or damaged pins. I also read something about the OBD fuse that could also cause this problem. Any help is greatly appreciated before I have to visit the dreaded dealership.

Mark what brand of OBD reader did you use?

[Hank Rogers]

I probably won't be much help, but I do remember that some cars had the
OBD fused on the same fuse for the cig lighter or power sockets.