I see there have been a number of threads on this over the years. Most of them have to do with water in the tail lights. I checked both of mine and no sign of water or corrosion there. I recently started getting these alerts in addition to the rear camera not working.

I hooked up forscan and see a PCM DTC U0298 Lost Communication with DC/DC convertor control module A. I also see IPC DTC's for U0232 and U0233, lost comms with side obstacle detection module a and B. I went through some of the old threads and see connector C408 pin 8 in the rear is what powers the bliss modules and rear camera. I checked for power there but do not see any on pin 8, but do on other pis. I also checked connector C275 pin 33 behind the air box. I dont see any signs of issues, but I also do not seem to be getting power there on pin 33 but again do see power on other pins. Finally I pulled the DC/DC convertor down from under the glove box and tested the white/brown cable directly on there and do not see power there either. I do get power on this module on other pins for this module, just not white/brown. All of this leads me to think the DC/DC box is bad.

Assuming I am on the right track and I am not over looking something else that may be down, Is there a way to test/attempt reset it the DC convertor with forscan? Is this replaceable at home or a dealer only thing? I see them on ebay and online but dont know if they have to be programmed vs just plug the new one in and it works. Any other tests I can run with forscan to further pin point the communication issues? Thanks in advance.

 

You're likely looking at old codes set at some time in the past.
Noticed that all are lost communication codes, not fault codes pe sey and not PCM codes (P codes).
If you have no other operating issues, your just wasting concern over it and learning as well.
Forscan should be able to test these sections.
If they come up as passed, you have no real issues.
Good luck.

 

I did not mention but I did clear the DTC's as well. They return immediately. I believed tracing down the white/brown wire not getting power would lead me to the cause of the bliss modules and rear camera not working. Just not sure how to determine why there is no power on pin 5 for that module

 

The red lead says battery from the junction box. Have you looked for the cause when the ignition is on?
.
The DC to DC converter looks at the Battery voltage value (SOC).
if ok, the DC converter supplies voltage to only key needed Modules for the Auto start function because the starter may drop the Battery voltage too low for them. Otherwise the DC converter raises the voltage to keep the Auto start function working.
If the DC system sees the voltage is too low or >>>missing, it inhibits Auto starting and sends a signal to the Dash to >>>Manually start the engine.
Are you having Auto start issues?

 

Yes, with ignition on is when I've been testing to see why my bliss modules and rear cam were not working. I started back at rear harness C408 connector then made my way forward to the connecter behind air filter, then finally to the DC converter where I discover that pin 5 on the DC converter is not putting out anything which seems to be the source for the bliss and rear camera power feed. The red lead (pin 8) on that module and a couple others have 12+ volts when I tested, just not the white/brown on pin 5.

The auto start button above the screen does work when toggled (turns yellow when pressed to turn off) and I see an accompanying message on dash telling me it is on or off, but the truck does not actually turn off when at stop lights so I do not think that system is working properly either.