Electrical trouble, codes p0606, p0500 and p0500 p this week

Hi guys, wondering if anyone has any insight. Check engine light has been coming on intermittently past few weeks. First time I checked it read p0606, ECM failure. Turned light off and 2 days later it's back on p0500 and p0500 p and the speedo isn't working. I think my battery may be on it's way out so I load tested it and it passed. Any ideas? 2006 4.0L 4WD TRD Off-road

 

Possible ground issues. Check the main ground from battery to where it lands. My buddy had a customers car having staring with issues. He thought battery too and load tested it good. Then issue went away could not replicate. It had just a little green on the ground hardly noticeable. The car came back (no charge) and he replaced the main ground cause it was a little suspect. No more problem. He made sure to have customer let him know.

 

Myself and another member had the P0500 code and it turned out to be a faulty speedometer cluster for both of us. If you decide to try a new speedometer just make sure the part numbers match and it's from the SAME exact truck(06 V6 A/T with/without vsc etc)

 

Update, odometer also isn't working and truck stalled this morning instantly after starting. Started the second try. Anyone know where the speed sensor is on a 2nd gen?

 

There are 2 on the automatic transmission.

 

There are 2 ways the speed is sent to the engine ecu. One is the speed sensor input taken from the trans straight to the engine ecu for powertrain controls. For the Speedometer & abs control, it takes inputs from the 4 abs sensors to the abs actuator/ecu then it's sent to the speedometer & back to the engine ecu.

 

The 606 is a shorted out rear o2 sensor

 

Another update, reset the abs system and speedometer came back and check engine light is gone. Still haven't figured out what is causing these electrical issues, something is going on. Stay tuned.