MM3 Install On 2018 RAM

[BABYKLEM]

I am having a 15012 error repeatedly while trying to set up a new MM3.

Does anyone have experience with this on an 18?

Do I need a bypass cable?

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[watersupply189]

I am having a 15012 error repeatedly while trying to set up a new MM3.

Does anyone have experience with this on an 18?

Do I need a bypass cable?

Yes, I believe you do need one.


2016 Ram Laramie 3500, G56, 6.7, CC, 4x4

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[Channelbouy]

I have a 2018 as well.

All I have done so far is get the stock file, and I haven’t had any issues.

I haven’t loaded anything yet, but I am curious if I will need a bypass cable, so I am following up.

Were you able to get the stock file without the bypass cable?

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BABYKLEM Yeah it was no issue getting the stock file off. However I cannot get the custom file to download to my truck, so I ordered the bypass.

02-28-2024

[BABYKLEM]

Bypass cable in & still having 15012 “Write ECM request failed!”

I’ve checked & rechecked everything.

I am waiting for MM3 tech to get back to me at this point.

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[AK Bob]

Bypass cable in & still having 15012 “Write ECM request failed!”

I’ve checked & rechecked everything.

I am waiting for MM3 tech to get back to me at this point.

If the OTF cable is good and connected to the J1939 plug in the engine bay, you may have a bad MM3 communication module.

The MM3 tech will help you troubleshoot and provide warranty support.

Please keep us posted on the fix.

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[BABYKLEM]

Alright, after a few weeks of screwing around & waiting on various parts, I finally have a running driving truck.

The MM3 Issue: Years ago, when I leveled my truck & put bigger tires on it, I used an AEV Procal module to set my TPMS, Tire size, & Fog Lights on w/ Hi-beams.

It turns out that the MM3 didn’t like this.

So, here is some info for the next guy: my truck did NOT need a bypass cable to program custom tunes with the MM3.

I bought one and installed it, and it made no difference. I still had an error.

MM3 tech said it was rare that 2018 would need the bypass cable to utilize the MM3.

So what gave me issues was that the protocol module required two wires from the OBD2 port to the star connector; the MM3 did NOT like that.

It was inconclusive whether or not I needed to set the truck stock again w/ the protocol, but airing on the side of caution, I did it and will use only the MM3 to set my TPMS, Tire size, etc.

Based on my research, the MM3 will also NOT like trying to tune over an H&S; if you’re in that situation, I believe you need to use the H&S to go back stock & then start fresh with the MM3.

I hope this helps someone in the future.

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[Channelbouy]

Thanks for the update!!

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[watersupply189]

Thank you for the update, and I'm glad you figured it out.


2016 Ram Laramie 3500, G56, 6.7, CC, 4x4

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[Corkey]

Glad you got her fixed!

If you add the previous tuner before purchasing, they might add a recovery stock file with the tune.

This allows the MM3 to communicate with the ECM\PCM correctly.

Going over H&S with the MM3 was more less the conflict, it wasn't recognizing the commands due to the stock box tune file configured when built.

MM3 uses an actual Mopar\CRYSTLER file just from the factory, allowing the MM3 tunes to communicate perfectly.

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