Corolla OBD Failure

Hello,

I have a 1997 Corolla with ~72k miles on it (7AFE engine). Went in for
emissions testing today, and it failed because the OBD system was
inoperable. The OBD system did not respond to the checks/tests. The
check-engine light does light up when the key is in the ON position,
and then turns off once the car has started. No driveability issues.

Any ideas where I should start looking for problems?

Here in IL, if the car is 1996 or newer, they don't do the actual
exhaust tests in case of OBD failure... so I have no choice but to have
this remedied before taking it in for a re-test.

Thanks in advance,

Nirav
97 Corolla, 72k

You have a data port along the bottom edge of the dash board in the area
where your left knee goes while you are driving. Some Auto Parts stores will
let you use the OBD II Code Reader for free in the parking lot of the store,
and some will let you take the reader home - they will show it as a sale on
your credit card, then give a full credit when you return the tool.

I would be using the code reader to take a look at the computer system in
the car. If the computer really is toast, you'll need to buy a new one.





"njmodi" <njmodi2@yahoo.com> wrote in message
news:1120070792.374457.319470@f14g2000cwb.googlegroups.com...[color=blue]
> Hello,
>
> I have a 1997 Corolla with ~72k miles on it (7AFE engine). Went in for
> emissions testing today, and it failed because the OBD system was
> inoperable. The OBD system did not respond to the checks/tests. The
> check-engine light does light up when the key is in the ON position,
> and then turns off once the car has started. No driveability issues.
>
> Any ideas where I should start looking for problems?
>
> Here in IL, if the car is 1996 or newer, they don't do the actual
> exhaust tests in case of OBD failure... so I have no choice but to have
> this remedied before taking it in for a re-test.
>
> Thanks in advance,
>
> Nirav
> 97 Corolla, 72k
>[/color]

"Jeff Strickland" <spamcatcher@yahoo.net> wrote in message
news:ttGdnck0oe9Ncl_fRVn-pA@ez2.net...[color=blue]
> You have a data port along the bottom edge of the dash board in the area
> where your left knee goes while you are driving. Some Auto Parts stores
> will
> let you use the OBD II Code Reader for free in the parking lot of the
> store,
> and some will let you take the reader home - they will show it as a sale
> on
> your credit card, then give a full credit when you return the tool.
>
> I would be using the code reader to take a look at the computer system in
> the car. If the computer really is toast, you'll need to buy a new one.
>[/color]

Where in IL is the OP? I'm willing to do a scan with my OBD II scan tool if
the OP is reasonably close to me.
--
Ray O
correct the return address punctuation to reply
[color=blue]
>
>
> "njmodi" <njmodi2@yahoo.com> wrote in message
> news:1120070792.374457.319470@f14g2000cwb.googlegroups.com...[color=green]
>> Hello,
>>
>> I have a 1997 Corolla with ~72k miles on it (7AFE engine). Went in for
>> emissions testing today, and it failed because the OBD system was
>> inoperable. The OBD system did not respond to the checks/tests. The
>> check-engine light does light up when the key is in the ON position,
>> and then turns off once the car has started. No driveability issues.
>>
>> Any ideas where I should start looking for problems?
>>
>> Here in IL, if the car is 1996 or newer, they don't do the actual
>> exhaust tests in case of OBD failure... so I have no choice but to have
>> this remedied before taking it in for a re-test.
>>
>> Thanks in advance,
>>
>> Nirav
>> 97 Corolla, 72k
>>[/color]
>
>[/color]

I'm in the Chicago metro area.... I'd really appreciate any/all help to
get this resolved.

Thanks,
Nirav

"Ray O" <rokigawa@tristarassociatesDOT.com> wrote in message
news:YaSdnUClHtk-ZF_fRVn-qA@comcast.com...


Ray,
I haven't ever heard of a computer shutting down like I think he is saying.
I suppose it could happen, but wouldn't there be a blown fuse or something
along those lines to be looking at first? I am a bit mystified how the Check
light can be working and the computer not be working.

I would highly doubt that the ECU would be the culprit... my guess is
there is a bad/loose wire to the OBD connector... I may dig around for
a OBD-II pinout to see if I can check for basic voltages etc.

Thanks for the help so far!

Nirav

"njmodi" <njmodi2@yahoo.com> wrote in message
news:1120074743.226505.50730@z14g2000cwz.googlegroups.com...[color=blue]
>I would highly doubt that the ECU would be the culprit... my guess is
> there is a bad/loose wire to the OBD connector... I may dig around for
> a OBD-II pinout to see if I can check for basic voltages etc.
>
> Thanks for the help so far!
>
> Nirav
>[/color]

Nirav,

ECU's have an extremely low failure rate - so low that the company that
checks ECU's returned for warranty repairs for Toyota sees only 1 or 2 bad
defective ECU's every 5 years or so. The rest of the ones they check have
either been damaged or check good.

The OBD connector is under the driver's side of the dashboard. It will be
shaped somewhat like a PC's parallel connector, only fatter.

Where in the Chicago area? Northwest suburbs?
--
Ray O
correct the return address punctuation to reply

No problem. I have this nagging suspicion that the guy at the inspection
station has been smoking his medical marajuana at lunch. I'm stuck on the
feeling that if the computer was completely out, then the car would be
running at all. I suppose it could be hard wired to a Safe Mode, but it
seems to me that if it was operating in the safe mode, the check light ought
to be on.





"njmodi" <njmodi2@yahoo.com> wrote in message
news:1120074743.226505.50730@z14g2000cwz.googlegroups.com...[color=blue]
> I would highly doubt that the ECU would be the culprit... my guess is
> there is a bad/loose wire to the OBD connector... I may dig around for
> a OBD-II pinout to see if I can check for basic voltages etc.
>
> Thanks for the help so far!
>
> Nirav
>[/color]

Jeff,

I wish I could blame the tester, but since this has happened two test
cycles in a row (on different equipment, 2 years apart), I'm sure there
is a problem at my end. The car drives fine - no issues whatsoever, so
I'm really hoping its just a bad wire. Any pointers to a pinout for
the connector where I can possibly verify some voltages/grounds to help
trace a bad wire?

Nirav


Jeff Strickland wrote:[color=blue]
> No problem. I have this nagging suspicion that the guy at the inspection
> station has been smoking his medical marajuana at lunch. I'm stuck on the
> feeling that if the computer was completely out, then the car would be
> running at all. I suppose it could be hard wired to a Safe Mode, but it
> seems to me that if it was operating in the safe mode, the check light ought
> to be on.
>[/color]

"njmodi" <njmodi2@yahoo.com> wrote in message
news:1120075535.424571.141920@o13g2000cwo.googlegroups.com...[color=blue]
> I'm right at I-355 and I-88... so I can go anywhere (if traffic is on
> my side) within 1/2 hour to 45 mins. I had the same problem during
> emission testing 2 years ago - but at that time they let me do the
> actual dyno tests because the new testing laws were not in effect yet.
> I had to get retested (2 yrs have passed) so I went over lunch, and
> they failed me because their computer wouldn't communicate with the OBD
> port (you mention). When it happened 2 years ago I just brushed it
> aside as an one-off failure with their system - but now that it
> happened again, I'm fairly certain there is something wrong with the
> vehicle.
>
> I am familiar with the OBD-II connector - in my other vehicle (a
> Nissan), I am able to follow a sequence of silly steps to have the the
> OBD system blink out the codes. No such feature on my 97 Corolla.
>
> I would think that a bad ECU would cause other issues with the car and
> (knock on wood) there have been none.
>
> Nirav
>[/color]
A Bad ECU would probably cause other issues with the car so you can probably
rule that out.

Visit a local auto parts store like Pep Boys or Auto Zone to see if they
will do a free scan for you. If you do a scan and nothing comes up, then,
if you have a multimeter:

Look at the check connecter (known as a DLC3 connector). There will be 2
rows of terminals/pins.

The bottom row (wide part of the DLC3) has terminals 1 through 8, counting
from the lower right to the lower left.
The top row (narrow part of the DLC3) has terminals 9 through 16, counter
from upper right to upper left.

Terminal #7 is the pulse generator during signal transmission - voltage will
be on-off.

Terminal #4 and #5 should always have less than 1 ohm of resistance between
the terminal and body ground.
Terminal #16 should always have between 9 and 14 volts between the terminal
and body ground.

There are standard values for the ECU as well although I do not have that
info handy. You can go to Toyota's web site and purchase info or try
AllData for info.

I live in the Schaumburg area. If you want to travel that far, send me an
e-mail.

Good luck!
--
Ray O
correct the return address punctuation to reply

Ray - that is great information. My initial plan of attack was to go
to Autozone and see if they had the same troubles. If they did, I was
going to try to jiggle the harness/connector and see if I could get it
to work.

If that fails, I'll pull out the multimeter at home and go through the
checks you posted. I will post back later this evening with my
findings.

For Terminal #7, should I check for voltages pulses between #7 and body
ground or do I need to check relative to one of the other terminals?

I do appreciate your offer of additional help, and all the responses so
far!

Nirav

"njmodi" <njmodi2@yahoo.com> wrote in message
news:1120078393.799752.270350@g14g2000cwa.googlegroups.com...[color=blue]
> Ray - that is great information. My initial plan of attack was to go
> to Autozone and see if they had the same troubles. If they did, I was
> going to try to jiggle the harness/connector and see if I could get it
> to work.[/color]

While you're at it, if you have any aftermarket accessories like a security
system, remote starter, or stereo, make sure that nobody tapped into a wire
leading to the DLC3 connector.
[color=blue]
>
> If that fails, I'll pull out the multimeter at home and go through the
> checks you posted. I will post back later this evening with my
> findings.
>
> For Terminal #7, should I check for voltages pulses between #7 and body
> ground or do I need to check relative to one of the other terminals?[/color]

Body ground.
[color=blue]
>
> I do appreciate your offer of additional help, and all the responses so
> far!
>
> Nirav
>[/color]

You're welcome!
--
Ray O
correct the return address punctuation to reply

"Jeff Strickland" <spamcatcher@yahoo.net> wrote:
[color=blue]
>
>I would be using the code reader to take a look at the computer system in
>the car. If the computer really is toast, you'll need to buy a new one.
>
>[/color]
Jeff, wouldn't you know it if the computer were toast?...I
wouldn't think it'd run at all would it?...
--


-Gord.

"I'm trying to get as old as I can,
and it must be working 'cause I'm
the oldest now that I've ever been"

"Gord Beaman" <gord@islandtelecom.com> wrote in message
news:qd56c15r2kmcdj86pgp7n870e518evrp22@4ax.com...[color=blue]
> "Jeff Strickland" <spamcatcher@yahoo.net> wrote:
>[color=green]
> >
> >I would be using the code reader to take a look at the computer system in
> >the car. If the computer really is toast, you'll need to buy a new one.
> >
> >[/color]
> Jeff, wouldn't you know it if the computer were toast?...I
> wouldn't think it'd run at all would it?...[/color]


That's what I was thinkin'.

I can't imagine how the OP could drive the car to the inspection station if
the inspector was going to tell him that the computer doesn't work.

"njmodi" <njmodi2@yahoo.com> wrote in message
news:1120078393.799752.270350@g14g2000cwa.googlegroups.com...[color=blue]
> Ray - that is great information. My initial plan of attack was to go
> to Autozone and see if they had the same troubles. If they did, I was
> going to try to jiggle the harness/connector and see if I could get it
> to work.
>
> If that fails, I'll pull out the multimeter at home and go through the
> checks you posted. I will post back later this evening with my
> findings.
>
> For Terminal #7, should I check for voltages pulses between #7 and body
> ground or do I need to check relative to one of the other terminals?
>[/color]

Terminal 7 is body ground. It would be good to confirm that it really is
ground.




[color=blue]
> I do appreciate your offer of additional help, and all the responses so
> far!
>
> Nirav
>[/color]