Had all 5 of these codes pop up at once after changing all of my better connections while trying to figure out my electrical issues. I’ve been dealing with a p0121 off and on for 3-4 months, replaced my APPS, dead pedal came back 3 wks later. Coincidentally my trans (auto) started not going into gear in drive or reverse until I rev up to about 1k rpm’s. I did the BD diesel noise isolator and for a few days it drove perfectly with zero shifting issues or dead pedal. Then started having overboost codes and then the truck randomly died twice. Replaced batteries and redid connections and triple checked the connections, and now I have those 5 codes. Thinking ECM going out due to alternator? Thoughts?

And how would I test my ecm to find out?

On 9/18/2023 at 5:25 PM, whuhta71 said:

I did the BD diesel noise isolator and for a few days it drove perfectly with zero shifting issues or dead pedal.

 

First thing rip that BD noise filter off the truck and toss it in the trash. That is going to burn up your VP44 and ECM.

 

Second off you need to test and replace your current alternator if it's weak or excessive AC noise. Then do the W-T ground wire mod. Takes about 25 dollars and about 1 to 2 hours time. 

 

 

On 9/18/2023 at 5:25 PM, whuhta71 said:

Thinking ECM going out due to alternator?

No its going out because of the AC noise filter you installed. You trying to cover up a AC noise issue that is affecting transmission, ECM, PCM and the VP44. Pull the noise filter off and replace the alternator and do the W-T ground wire mod. 

Interesting, disconnected and threw out bd noise filter, disconnected tuner and what not. Code went back to just p0236 and the APPS code, tested my alternator I think correctly and got .146 ac volts. That’s a bad alternator, so the question is, how likely is it that my ecm is bad from it?

I would do the W-T ground wiring mod first and then recheck the alternator for stray AC voltage.   Also, I think the test should be done after the grid heaters stop their post cycling, otherwise you can have higher than normal readings.

 

I am still running my original alternator (replaced brushes and bearings at 216,000 miles)  Currently at 380,000 miles with no AC voltage issues.

 

- John

I must’ve done something wrong with the ground wire mod…? I hooked everything back up after doing the ground wire mod and replacing alternator and it fired up no check engine lights but the battery gauge kept climbing wayy high so I shut the truck off.

3 hours ago, whuhta71 said:

but the battery gauge kept climbing wayy high so I shut the truck off.

 

Double-check that your positive cross-over cable is connected.  Verify that you didn't miss any other wiring connections.

 

I would start the engine and quickly check voltage at each battery individually to see if it agrees with what dash voltmeter is showing.  Both batteries should read the same voltage.  Report back what you find.

 

- John

Hey sorry for not updating this post last night, wrapped up around 4 am too tired to think straight. I did end up going back through everything and redid my connections and hooked it up again,  don’t know what was the culprit but it doesn’t do that now. Also checked the ac voltage at the alternator, went from .146v to .021 and no check engine this morning.

Glad to hearing everything is working properly and no codes.  Would have been interesting to know if the W-T ground wiring mod would have corrected the old alternator high AC voltage.

 

- John

Yeah I was going to do that but I was pretty sure my alternator was on the way out anyways as it was. Voltage was pretty inconsistent and sometimes weak over the last couple weeks.

now the only problem I have to fix is a bad torque converter/trans it doesn’t go into gear until you give it a bit of throttle at idle and sometimes randomly disengages/slips while driving.

🤣😂🤣😂🤣😂🤣😂

Here ya go.....😂🤣😂🤣😂🤣😂🤣

 

 

 

 

https://www.cumminsforum.com/threads/auto-trans-erratic-shift-solved-with-engine-oil-change.2585351/#post-29836667

1 hour ago, Max Tune said:

Here ya go.....

 

Wow!  Same thing happened to me, and I have a manual transmission!  What are the odds?!

 

- John

Well, APPS code came back and I get occasional dead pedal again… don’t know if that means my alternator fried the new Apps too? I have done the Apps reset twice now.

Test it. Either pull the alternator and have it spun tested. Or find a shop that can do the test on the charging system. The bare minimum would be grab a DVM and measure the AC volts should not be above 0.05 Volts.