P2121 & p2127

[Aussie]

Can someone please help, I have a 2012 3500 Dodge Ram I am in Australia so have limited expertise in these vehicles here. I have the lightning bolt (ETC) & engine light coming on & it will then go into limp mode. I have had on the scanner and it shows P2121 & P2127 once cleared it can run for a while without coming back on but then all of a sudden will do it again. I've checked out some forums and people have changed the APPS but still hasn't fixed the problem so I was reluctant to do this. Can someone please give me some advice? I'm desperately needing this fixed, thanks in advance

 

[Wayne M.]

Hey Mate! Welcome to the TDR. I'm not a 4th gen guy, but a 3rd gen owner, but I do watch all the forums, and I'm a Mechanic by trade. I do believe your post is the first time I'm seeing an APPS issue with a 4gen.
This happens with 3 gen trucks quite often, and sometimes it winds up being the APPS itself, but more often (I believe) it's some other noise in the engine harness, like possibly a short.
I personally had the P2121 and almost at the same time fan clutch issues causing low Air conditioning output (high condenser temp) and upon changing the clutch, found a rubbed through harness. Once I changed the clutch, my A/C came back, and I never had a P2121 again. And yes, I went for a expensive APPS in the process, since I do not own an oscilloscope to professionally diagnose the issue.
There are a couple of active dealer Techs on the TDR. Perhaps someone will know of a TSB or other pattern failure pertaining to the newer trucks. Good luck!

 

[Aussie]

G'day Wayne,
Thanks for the reply. Funny you should say that, the air conditioner stopped working a couple of months ago (no fan) so I replaced the fan, it only lasted a few weeks & it went again. The guys thought it must've been faulty so just put a new one in. Then this started happening about 4 weeks later.
Think I will get someone to check the engine harness out before replacing the APPS. Thanks again.

Hey Mate! Welcome to the TDR. I'm not a 4th gen guy, but a 3rd gen owner, but I do watch all the forums, and I'm a Mechanic by trade. I do believe your post is the first time I'm seeing an APPS issue with a 4gen.
This happens with 3 gen trucks quite often, and sometimes it winds up being the APPS itself, but more often (I believe) it's some other noise in the engine harness, like possibly a short.
I personally had the P2121 and almost at the same time fan clutch issues causing low Air conditioning output (high condenser temp) and upon changing the clutch, found a rubbed through harness. Once I changed the clutch, my A/C came back, and I never had a P2121 again. And yes, I went for a expensive APPS in the process, since I do not own an oscilloscope to professionally diagnose the issue.
There are a couple of active dealer Techs on the TDR. Perhaps someone will know of a TSB or other pattern failure pertaining to the newer trucks. Good luck!

 

[TCDiesel]

Wayne is correct on Fan Issue's I see it all the time form 2006-16, is it OEM fan or aftermarket?

 

[Wayne M.]

G'day Wayne,
Thanks for the reply. Funny you should say that, the air conditioner stopped working a couple of months ago (no fan) so I replaced the fan, it only lasted a few weeks & it went again. The guys thought it must've been faulty so just put a new one in. Then this started happening about 4 weeks later.
Think I will get someone to check the engine harness out before replacing the APPS. Thanks again.

Which fan did you replace? The Blower motor fan in the cab, or the engine cooling fan under the hood?

 

[Aussie]

Was the fan in the cab under the glove compartment

Which fan did you replace? The Blower motor fan in the cab, or the engine cooling fan under the hood?

 

[Aussie]

I think it would've been OEM the guys that converted it from left to right hand drive replaced it, I will check with them on Monday

 

[Wayne M.]

I think it would've been OEM the guys that converted it from left to right hand drive replaced it, I will check with them on Monday

Oh hey wow! I don't think I've ever seen a RHD RAM! Can you take some pictures for us? This is especially interesting since I don't think the Ram dash and firewall is symmetrical. I have questions like how was the steering and brake pedal linkage reworked?
And this opens up a whole can of worms in terms of potential electrical issues! You definetly need to get the blower issue nailed down.

 

[Aussie]

I have actually just driven it 8 hours up to Brisbane to have it hooked up for Air Brakes for the Trailer I'm going to haul. When it comes back I can take some photos for you. It costs about $35,000 to have them converted, I wish we just drove on the same side as you guys lol. It has been 4 years now since it has been on the road here, but will definitely start looking into the electrical side. Thank you

Oh hey wow! I don't think I've ever seen a RHD RAM! Can you take some pictures for us? This is especially interesting since I don't think the Ram dash and firewall is symmetrical. I have questions like how was the steering and brake pedal linkage reworked?
And this opens up a whole can of worms in terms of potential electrical issues! You definetly need to get the blower issue nailed down.