SMOG Readiness-Catalyst Monitor

[freshspecbluegt]

I had my 95 apart to rebuild the steering (steering box, pump, lines, etc.) and as a result I had the battery out for about a month. I got everything put back together and the truck is running great. I just spent 4 days in the eastern sierras with it and it performed great even above 10,000ft.

My problem is I need to SMOG it and it won't go to "ready" state even with ~ 1,000 miles and 20+ start stop cycles on it since the battery was hooked up. The check engine light is not on and there are no codes.

I checked the readiness monitors with my scangauge and the Catalyst Monitor is not ready.

Full tune up was done a couple of years ago, timing is set right at factory spec, new intake tube so no cracks or leaks. The only thing I haven't done is replace the O2 sensors.

Could the O2 sensors be borderline? Still performing well enough to not throw a code but not allowing the readiness monitor to be set?

Also can some post the required drive cycle to get the ECM to ready mode in case I need to unhook the battery again. SMOG is already past due!

 

[george_tlc]

Readiness for a '96 (from the manual) shows the recommended drive cycle.

I've attached just the readiness page. Hopefully that helps.

cheers,
george.

 

[jcardona1]

Readiness for a '96 (from the manual) shows the recommended drive cycle.

I've attached just the readiness page. Hopefully that helps.

cheers,
george.

That's the wrong one. The FSM only shows the drive cycle for the EGR monitor.

Here's the service bulletin that shows the drive cycles for each monitor. Catalyst monitor for a LC is shown on page 12. The bulletin says it's for '96-02 vehicles but if you're '95 is fully OBDII compliant then it should be the same.

http://www.watrd.com/work/TSB_EG003-02_(revised).pdf

And FWIW, our trucks have separate monitors for the Catalyst and O2 Sensors. Here's a screenshot showing the monitors we have available

 

[jcardona1]

Another thing to note is that the monitor may never switch to ready if it the computer reads a potential problem. That was my issue. I had a check engine light come on for a bad O2 sensor so I cleared the codes and ordered a new sensor. Even with several hundred miles of driving the monitors never switched to Ready. Once I swapped in the new sensor all was well again and they showed as Ready.

You'll see this footnote at the bottom of each page.

 

[george_tlc]

Jose, great document, just saved it for a rainy day.

cheers,
george.

 

[freshspecbluegt]

Jose,

Thanks for the doc.

I finally got the truck into ready state. I tried to get it ready using the drive cycles in the doc. but it just wouldn't go. I swapped out the 02 sensors and even after unhooking the battery again it only took about 75 miles of normal driving for it to go into ready mode.

The O2 sensors must have been about ready to fail. I thought both had been changed by the PO but it turned out only the front had been changed after I rechecked their receipts.

I also checked the smog results from 2 years ago and compared them to the results from when I smogged it 4 years ago. The HC were creeping up and the truck passed but the HC's had doubled. We'll see what it looks like when it is smogged later this week.

Thanks for the help.

 

[alaskacruiser]

freshspecbluegt- thread resurrection, as I'm in the same boat with cat not ready, even after following the recommended drive cycle many times. Since it seems your O2 sensors may have been the problem, I'm just wondering if your O2's also showed as not ready?