Disabling DTCs for non-existent systems on the 7.3L
 

Here we are, nearly 20 years after the release of the last 7.3L Power Stroke Diesel, and the vehicles are still running strong. The aftermarket and used vehicle market illustrates just how reliable and desirable these vehicles are. However, the are a few drawbacks to having an older vehicle, and the factory availability of certain electronics is one of those drawbacks.

Motorcraft no longer manufactures new PCMs for the 7.3L Power Stroke. The only source for these is in the remanufactured market, and even then these can be difficult to source. Given the increasing difficulty in finding PCMs to replace damaged ones, it is occasionally necessary to utilize a newer model PCM in order to get an older vehicle up and running. While this is technically valid solution, the issue that occurs when using this approach is that new PCMs may be designed to control systems that may not be present on an earlier model vehicle. In these situations, you may end up with 1 or more DTCs that pertain to the non-existent system on the vehicle, which creates a problem.

For example, if you install a DPC-422 PCM from a 2001 Federal truck into an early 1999 Federal truck which uses a DPC-402 PCM, you'll end up with a DTC for the Intake Air Heater which does not exist in the early 1999 trucks. Usually this DTC will be P0541, P0542, or P0640, which indicates a circuit issue with the Intake Air Heater. Another system that may not be present would be the Exhaust Back Pressure Control Valve, which would exhibit a DTC P0475, P0476, or P0478 which indicates a circuit issue with the non-existent solenoid.

In order to prevent the PCM from monitoring the non-existent system, it becomes necessary to disable the related DTC(s). This will allow the vehicle to function normally without any adverse effects on drivability or emissions.

To disable a specific DTC, you will need to locate the DTC in question under the Parameters List. In the above example related to the Intake Air Heater, we would look for the above listed DTCs... P0541, P0542, and P0640... and then turn them off. This would effectively disable the PCM from monitoring the system that doesn't exist on the vehicle.

To turn off the monitoring for a specific DTC, you would enter a value of 0x9999 (39321) for that DTC. If the value is already displayed as 0x9999, then that specific system is not active.

Please Note: Power Hungry Performance does not recommend or condone the disabling of any DTCs that could relate to engine performance, critical systems, or emissions systems related issues. In these situations, the only reasonable course of action is to correct issue in order to maintain the proper functionality of the system.

I hope this is helpful.

Thank you Bill. While disabling DTCs isn't something I have done, it's great to have that option.

Thanks for the hard work. These vehicles are still going strong and it's nice you still put in the work to support them!