Ok so I just noticed that when I turn the key on and before I start the engine, the MIL/CEL light lights up solid like normal, but then after about 10 seconds it starts blinking for about 5 seconds, then goes solid again. Once I start the engine, the MIL extinguishes like normal. Truck runs perfectly normal. Also did the cycling the key 3 times and no codes came up--it went right to 'done'. The OM just says if this happens, then it's not ready for emissions testing--which doesn't tell me much. So what gives? Anyone had this? thanks!

 

If you have no codes and the truck is running fine there is no concern. Now if your truck is acting up you could have a computer code.

How to display 'C' codes:

Press the odometer trip reset, hold it, then turn the key to the 'ON' position. Do not engage starter. Once the gauge check starts, you can release the button. Once it is done with the gauge check, it will display 'C' codes.

 

After I change my fuel filter and just bump the starter mine does the same thing. As soon as you start the engine and it goes off no worries.

 

Ok thanks. I checked and I do have 2 C-Codes, they are:

68-Driver door unlock output circuit shorted to ground or voltage
AC-ABS messages not received

Would these codes make the MIL flash? The 68 code, I'm guessing is the crappy wiring from the body to the door coming apart, like it did on my driver's rear door. I can fix that. Not sure about the AC code though. My ABS brakes are working fine from what I can tell (I did a quick panic stop to check and the ABS did engage). Ever had these codes and have any further info on what's the cause and the fix? Thanks.

 

this is normal. those codes wont make the CEL flash. flashing CEL (on gasser rigs) is a severe missfire and is yelling at you to shut it off and tow it to get repared.