Hello all! I am new to this forum and would like to thank all in advance for reading and or helping with my trouble. I have a 2003 Sierra 2500HD 6.0l. I was getting the check engine light flashing @70 mph. I read all through the forums to see what helped other people, and decided to change MAP sensor, Crankshaft sensor, and Camshaft sensor, because these are the main things that control the timing system. I also pulled the grounds and cleaned/scuffed and retightened. Now that I have done all of this it starts flashing @30 and continues to flash all through the driving range until I stop..........should've left it alone! I've decided I'm going to put the old sensors back on 1 at a time and drive it in between to see if it will even go back to just flashing @70 now or if this is the new thing.....annoying!

Did you replace Plugs and Wires? Check for spark at each coil pack. Also try tolean the Mass Airflow Sensor.

OK so here it goes..I put the old MAP sensor first and drove it..no changes. Next I put the old Cam sensor and drove it..no changes. Last I put the old Crank sensor and drove it, and now it seems to be cured! It doesn't even flash at 70 anymore! I believe the reason is the rust. This truck has an extreme amount of rust (maybe from up north?)(Road salt?). My brake lines have rusted completely through once already, and I had to replace the starter because the posts that hold the wires were so rusted they broke off when removing the nuts (to change the crank sensor). Anyhow before I put the sensor back in I took a sharp flathead screwdriver and a sharp punch and scraped as much rust off where the sensor seats and where the mounting tab bolts on. Hopefully this info will help others having the same problem.


*I'll Keep my Fingers Crossed*
(and try to return the sensors)

Welcome

Howdy