"Mark" wrote in message
>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!
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.