Good morning gang. My uncles 99 has no wait to start light however the grids cycle after it starts. With a test light there is no trigger from the ecm when you cycle the key. No codes and it runs great. It also has a new IAT sensor. Thanks in advance for any guidance 

If youre lucky, it's the bulb... You can do a cluster test for the bulb here 

 

 

If that doesnt work, id start watching for a used ecm.

3 hours ago, CSM said:

If youre lucky, it's the bulb... You can do a cluster test for the bulb here 

 

 

If that doesnt work, id start watching for a used ecm.

Another way is to see if the P0381 code is present...

 

No codes.  I ran the instrument cluster test and it didn't illuminate so we'll check the bulb. I'm Hoping that's it but it's definitely not firing the grids. We're going to check in the morning when it's cold

I didnt see that there was no ecm signal... Sounds like ecm.

On 3/6/2016 at 11:46 AM, BBHD said:

No codes.  I ran the instrument cluster test and it didn't illuminate so we'll check the bulb. I'm Hoping that's it but it's definitely not firing the grids. We're going to check in the morning when it's cold

Any chance you have the MPG fooler and the switch is set for MPG improvement?  That tends to eliminate the need for grid heaters and a Wait To Start function.

No mpg/high idle switch on my uncles truck.  He has been thinking it was the ecm for a while. Going to call module masters and talk to them and see what they say.