Truck Died...won't start. P2509 code

[guyhaz]

Truck just all of a sudden died in the middle of the road. Won't start and throwing P2509 code. This is the second time in 2 days I have seen this code. First time the truck ran fine and went away after a couple of restarts. So I tested batteries they read 12.5 v each on multimeter. Cleaned terminals and checked electrical connections and ground. All good. Any thoughts what might be the issue. Bumped starter and opened drain on fuel filter housing and have good fuel pouring out. I am at a loss. Bad ECM? How do I check that?

 

[guyhaz]

Took both batteries up to parts store to have tested and both tested good.

 

[AH64ID]

Check the fender ground. It’s above the drivers side battery.

 

[guyhaz]

K. Checked it. Looks good.
Could a faulty grid heater relay cause a code p2509? It appears mine is going bad.

 

[Ozymandias]

https://www.obd-codes.com/p2509

Here are some good hints what can throw the p2509

There is way more involved in it then the ECM itself.

 

[cerberusiam]

Disconnect the grid heater solenoids and feed wire then test again. If ti doesn't start try some starting fluid and see if it low rail pressure or lack of injector operation.

 

[CrewCabDiesel]

starting fluid in a diesel is a bad idea, try WD40.

 

[sag2]

The P2509 means that one or more of the three ECM power feeds were lost while the ignition was on. Pull the ECM connector and verify that all three B+ terminals have power.

 

[guyhaz]

Thanks for all the replies guys. I replaced the grid heater relay that was going bad as it was starting to melt the 12v fuseable link coming off the passenger's side battery. Also the terminal was really hot. My guess is the relay was pulling way too much current causing the drop in power to the ECM, thus throwing the code. I replace the relay and wire and it has been running fine for a couple of days now.