is it blinking, or on solid?

 

My CEL came on a day or so ago. I had to return my serp belt from auto zone since they gave me the one for a dealer installed ac, not the factory installed ac (it was about 2 inches shorter). My old belt sounded like a stuck pig. On my way to Auto Zone, the CEL came on, but my truck felt normal. Had them check...no codes. Disconnected the battery and cleared the code. Replaced my serp belt last night, and the CEL hasn't shown up yet, but I'm watching for it.

 

It"s comes on solid and stays that way until cleared with scan tool, or I pull the neg battery cable for a bit. My IAC quit working awhile back and the CEL never came on , but I figured it was more of mechanical failure. Idle was stuck up around 1200 rpm until I replaced it. It drives me nuts to drive with it on, even with no codes.

 

That's kinda weird. If the lights on, the PCM is annoyed about something...... would be nice if it would TELL YOU what it was annoyed about..... I am just not into guessing games with my truck.

 

Update...The CEL came on couple more times at random miles driven. I did notice that it ran better for a short while after clearing the light, with no codes.
A few days ago (no light) I thought it was getting doggy so I did a quick reset, pulled the neg cable , turned the head lights on, stepped on the brake pedal, turned the key on 3 times....etc..
Ever since it's been running awesome, way more power, better throttle response, better transmission shifting, it even sounds different accelerating. I don't why, but I'm happier than a pig in mud. Didn't know what I was missing!

 

Clearing codes does exactly that. Clears codes. Disconnecting the battery resets the entire PCM. It forgets everything it ever knew about running your truck, and is forced to re-learn everything. Keep in mind, that your PCM also learns your driving STYLE. Maybe not part of the original intention of adaptive programming, but, it sure is a side benefit.

 

I've disconnected the battery around 5-6 times in the past few months. And just cleared the light with four different scan tools, that could not retrieve a code when the CEL was on, over last 6 months.
Is it possible the previous owner had used a tuner of some sort and all this resetting of the pcm finally got it back right. Because it was an immediate difference in engine performance after this last pcm reset. It was like taking 1000lbs off the truck. Feels light as a feather taking off from a dead stop. And it used to really fall on it's face going into overdrive, so much so,that I had got in the habit of hitting the OD off button.
Maybe my PCM is messed up and this is just a fluke, time will tell. I was thinking of trying a new pcm, but I'm going to wait on that. Any light you can shed on this mysterious behavior?

 

My 99 has the same deal. My code reader wont read it. The guy that had the truck before me had chrysler scan it and it came back with the computer wasnt sending a signal to the purge valve solenoid and the only way to fix it is a new pcm, it wasnt bothering anything so he just left it and i just scan the computer every few hundred miles to see if theres any stored codes.

 

Am having that same problem did you ever found out what it was ?