Check engine light flashes

[Ryan99ram]

I have my 1999 dodge ram with the 5.2. At highway speeds over 3000 rpm the check engine light will flash and there will be a terrible vibration. It only happens over 3000 rpm and there is no code to check because the light goes off and there is no history codes. Just looking for some imput. Thanks

 

[WhiteExpress]

I find it very stange that you get a 'fatal engine error' (blinking CEL) and it doesn't store any codes.

You mention it's only at highway speeds. If you manually shift the transmission and let the RPMs get above 3k RPM (say in first) do you still have the issue?

My initial though leans towards the transmission.

 

[jbmobbs]

i think it might be a few misfires cause if its shaking badly

 

[Ocelot]

I know on many OBDII systems cylinder misfires can cause a flashing check light. On my old Chevy Colorado, I had that same symptoms except it was after a load like going up a hill. The CEL would flash for a bit and go away with no stored code (I have a code reader)
I left the Scan Gauge set to trouble code display while driving and It took a couple times display the code for "random misfire"

It took a few more days to go to a steady CEL and I was able to pull the code for "cylinder 3 misfire" Changed the #3 coil pack and all was good.

Ray

 

[Ryan99ram]

Thank you guys for the input. Il have to make the truck have this problem with a code reader plugged in and see what I get