SES Light, But No Trouble Codes?

[gbmidyear66]

My SES light is comming on intemittently, with increasing regularity. I tried to check it last night in my garage with my AutoXray 60000 scanner - but wouldn't come on sitting at idle.

I drove it today with my scanner attached - wanting to catch the code that is triggering it.

The SES came on about 3 times for 20 seconds or so each time, but there are no trouble codes showing on the scanner? Any way to catch the source of these intermittent SES?

Possibly related.... I am having some idle issues, idle will hang high while driving and/or after coming to a stop (about 2,500, then will eventually come back down), can usually get it to come down to idle (driving or stopped) by blipping the throttle a few times. Checked that my PROM is seated, all my hoses (including MAP) are properly connected, secondary vacumm pump does not cycle, throttle plates are clean and don't seem to be sticking....

Any thoughts appreciated.

[Kevin]

could be 02 sensors

[GOLDCYLON]

Clean your IAC valve located on the side of the airhorn.

[gbmidyear66]

- Cleaned the IAC less than 3,000 miles ago - don't think that is it.

- TPS is reading correct voltage at idle, and ramps up smoothly with RPM

- On the O2 sensors... the voltage jumps around so much on the scanner, but Right and Left seem to be operating in same range and behaving similarly, I'll try to check them a little closer (crosscounts, etc).

[GOLDCYLON]

Trust me its a no cost look. And a dirty one will cause these idle issues. And a lot can happen in less than 3000 miles

[GOLDCYLON]

Originally Posted by Dynamite

Are you talking about the Idle Air Controller (IAC) valve on the passenger side of the Throttle Body?

The Manifold Air Temperature sensor (MAT) is located on the passenger side of the Airhorn (Throttle Body Extension).

IAC it is further back on the TB behind the Airhorn

[tomtom72]

Well, your O2 sensors seem to be okay by your description of the voltage behavior. They are supposed to change voltage so quickly as to make you dizzy.

Have you tried getting into the CCM? Sometimes if the DTC will not set the CCM picks it up & stores it as an "H" code, History code. I can't recall which pins on the ALDL to short.......I have Gordon's jumper kit, yea I cheat!

Let me ask, steady state cruise? Or hard acceleration? or moderate acceleration? Or steady high speeds like over 80 mph? Or it just has a mind of it's own?

Also, which base management program are you using? AUAH or AYBK? The 90's had a TSB on the AUAH program for the idle & coast down symptoms you're describing and the AYBK prom was issued to correct those symptoms, albeit in 1992!


Tom

[gbmidyear66]

Tom - that is very intersting. I tossed out the paper clip when I bought my AutoXray (but have a good supply in my desk...)

Do you happen to know the procedure to retrieve the "H" codes from the CCM?

I am getting the intrermittent SES under normal city/highway (mixed) driving, usually starts to appear after about 10 minutes of operation, it seems to be getting more frequent though - happened 3 times on my 20 minute drive in to the office today.

I've been runniung a "custom" prom on a Moates adapter for a year now. I have the original AUAH (with the stupid CAGS and the stupid high idle until dead stop) - I may put that back in just to see if it makes a diff - but I already pulled the adpater to make sure everything was seated well.

[GOLDCYLON]

Originally Posted by tomtom72

Have you tried getting into the CCM? Sometimes if the DTC will not set the CCM picks it up & stores it as an "H" code, History code. I can't recall which pins on the ALDL to short.......I have Gordon's jumper kit, yea I cheat!
Tom

Tom is right a CCM code could be set

[tomtom72]

You Da Man Cliff!

Terminal "A" is ground and terminal "G" is the line to the CCM. As you view the ALDL, A is top right and G is lower row left. Short those two and the speedo will dissolve into a data stream for the CCM, trouble is that I don't remember the rest as there are 4 modules of display......that stuff is in the Kit from Gordon so I never bothered to memorize it as it's always in my car.

Oh, the CSGS can be unplugged at the trans and left tapped up to keep dirt & such out of the connectors. The Prom don't care that it is unplugged, no DTC is set.

Okay, now this is an admission of stupidity on my part. I'm lost when you guys talk about MOATS stuff. Flightless birds & emulators & all that good chit I should learn.... but anyway I'll lay this on you because I have a piggy back thing plugged into my OE AYBK PROM and I lost the foam block on the door of the ECM. This is causing the PROM to loosen as I drive, and unless it gets real loose it doesn't even light the SES light, even flicker it. My issue is that the PROM cover had to be removed to plug in the piggy back thing, and now the hold down levers don't have anything to grab, they used to grab the stock prom cover ( that blue thing that the foam block used to rest on when the door is locked ) so it vibrates loose and is playing heck with the ECM.....I think it goes into retarded mode. Anyway, a loose prom is supposed to set a DTC 51 or a DTC41: 51= wrong or loose memcal; 41 = cylinder select error, which could also be a loose memcal.

Okay that's the sum of my knowledge on engine management programs and their workings!


Tom