My engine light is on but I'm not getting any codes. I had my truck diagnosed at Auto Zone many times before for other problems and they were very helpful. Is it possible that the light is malfunctioning? Or do I need to see the dealer?

If the Check Engine Light stays on, when the ignition switch is turned to ON, it may be indicating the PCM is failing.

If the Check Engine Light stays on, when the ignition switch is turned to ON, it may be indicating the PCM is failing.
Thanks. Is the pcm the main computer? Does anyone know ware its located in the Yukon?

Yes. It's likely located along the firewall (passenger's side) under the hood. Look for a large bundle of wires going to it.

Yes. It's likely located along the firewall (passenger's side) under the hood. Look for a large bundle of wires going to it.
Thank you!