MM3 issue

[hschuchard]

Hey everyone, I am new here and had a question about my 2018 Cummins 6.7L.

I recently tuned and deleted my truck with MM3 tuner.

The MM3 monitor part does not turn on when I start my truck, if I touch the screen it asks me to agree or not agree with the terms.

I hit agree and all the gauges say N/A on them.

If I unplug the OBD port and plug it back in all my gauges read fine.

Every time I start my truck back up it it does the same thing every time.

If you guys have any help thank you guys!

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[IGOTACUMMINS]

Who did you purchase the tuner from?

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[Aboshan]

I would check the OTP cable....first thing that came to mind when I read the post.

Another thing that can interfere is if you are sharing the OBDII port with AMP Research or similar electric running boards. It is not recommended

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[hschuchard]

It is from Milliken diesel performance in Texas

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[hschuchard]

And is the OTP cable the micro usb cable? If so I did replace that and it did not help.
Also I do not run AMP steps

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[watersupply189]

And is the OTP cable the micro usb cable? If so I did replace that and it did not help.
Also I do not run AMP steps

Make sure the two half’s of the “control box” is put together securely. If it has the metal screw tabs, remove them for a better connection.


2016 Ram Laramie 3500 (DRD), G56, 6.7, Rough Country Leveling, HID headlights, Morimoto LED fogs plus a whole lot more!

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[hschuchard]

I have the one piece black box not the 2 piece.

Also I tried not using the metal screws and it still didn’t help.

It’s almost as if my truck locks out the tuner when I shut off the truck and I need to reset it by undoing the obd.

Do you guys think I should try installing it back to stock then retuning it?

Let me know thanks.

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[watersupply189]

I have the one piece black box not the 2 piece.

Also I tried not using the metal screws and it still didn’t help.

It’s almost as if my truck locks out the tuner when I shut off the truck and I need to reset it by undoing the obd.

Do you guys think I should try installing it back to stock then retuning it?

Let me know thanks.

I was gonna say try returning it back to stock then retune it again. Make sure your batteries are fully charged before doing so.


2016 Ram Laramie 3500 (DRD), G56, 6.7, Rough Country Leveling, HID headlights, Morimoto LED fogs plus a whole lot more!

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[hschuchard]

This might be a dumb question but the cable that goes from the box to the connector under the hood, is that going to the ECM? Because talking with the guy I bought it from he says it appears it is losing power to the tuner.

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[CzechRooster]

I have the exact same issue, I even spent over $400 on new AGM batteries as the voltage was starting to get a little low. Truck still started fine but I've heard the MM3 is a little finicky on voltage. Surprisingly all parameters except the one from the EGT probe show N/A, till I reconnect the OBD. I did disconnect the plug to the ECM as I just run the 30hp tune. I'll reconnect and see if that helps.

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