Heater Core Replaced - Now My MM3 Is Dead?

[Gig]

Of course, they have to pull the entire dash, HVAC, and core out.

The tiny USB cable was hanging down as I figured they forgot to plug it in when I got it back.

When I got it home, it was dark, and I was not crawling around in the dark.

So, this morning I went out and plugged it back into the box under the dash, and still nothing as I figured it was dead.

The weird part is when you unplug the OBDII plug, and the dash goes out completely - analog and digital gauges as tt never did THAT before.

Headed to Myrtle Beach Friday and seems to run ok, but I don't like how it is acting.

Any thoughts?

There's no way the shop is going to own the tuner problem.

So I'm on my own here.

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[AK Bob]

So if I understand correctly, with nothing plugged into the OBD port, the analog and digital gauges on the dash are dead?

If this is the case, they must have disconnected or damaged the factory wiring when removing the dash.

They are responsible for this, and once fixed, your tuner should start working again.

I would remove the tuner and have them figure out why the dash gauges are not working.

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[Gig]

That's correct.

Unplugged, nothing works.

I've also decided that they must have some ownership in this.

The truck dash won't work.

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[AK Bob]

I would remove the tuner and take it with you when you have them fix the issue.

They need to get everything working with nothing plugged into the OBD port, then test the port for proper communication with all modules.


2014 RAM 3500 (Aisin) 3.73 4X4 Limited Crew Cab Long Bed DRW. Oil Bypass Filter, Fuel Filtration Kit, and 50 Gallon Aux Fuel Tank.

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[Gig]

So I got the truck back from them, taking another look.

They have it working now.

They said a ground wire wasn't connected, and I'm not sure where.

However, MM3 is still DOA.

I plugged it into my laptop, and I got two red lights, one green, then two red again, and a slight pause, and it starts over.

Not sure what that means exactly.

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[AK Bob]

The flashing LED can be caused by a power problem.

You should be able to measure Battery voltage between pins #16 and #4 on the OBDII port (see attached).

What did you plug into your laptop?

2B561985-ADEB-45B4-B148-8A08C999C5F6.jpeg

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[AK Bob]

So I got the truck back from them, taking another look.

They have it working now.

They said a ground wire wasn't connected, and I'm not sure where.

However, MM3 is still DOA.

I plugged it into my laptop, and I got two red lights, one green, then two red again, and a slight pause, and it starts over.

Not sure what that means exactly.

Just following up, any update?

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[Gig]

Thanks for checking up on me.

Just to be clear, the blinking only happened when I plugged into the laptop.

It doesnt even do that when plugged into the truck. It's acts dead.

Yeah, there's the power between 4 and 16 on the OBDII.

Tried formatting the card and reloading the files. Nope.

Tried a newly formatted card with reloaded files. Nope.

Checked the fuse for continuity under the hood. Good.

Triple checked the connections, which seems ok to me.

IDK pretty bummed right now.

The tuner was worth more than the heater core repair.

Grrr....

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[AK Bob]

Thanks for checking up on me.

Just to be clear, the blinking only happened when I plugged into the laptop.

It doesn't even do that when plugged into the truck. It's acts dead.

Yeah, there's the power between 4 and 16 on the OBDII.

Tried formatting the card and reloading the files. Nope.

Tried a newly formatted card with reloaded files. Nope.

Checked the fuse for continuity under the hood. Good.

Triple checked the connections, which seems ok to me.

IDK pretty bummed right now.

The tuner was worth more than the heater core repair.

Grrr...

Sorry to hear you are still having trouble.

First, I would verify that your OBDII port is working correctly by plugging in a scan tool.

If you don’t have one, stop by one of your local parts stores to make sure their scan tool will power up and communicate with your truck.

If the OBDII port tests well, then perhaps your MM3 unit was damaged when it acted as a ground after the initial heater core repair.

If you suspect this is the case, call MM3 Power tech support at (208) 346-7707 for further troubleshooting steps, possible repair, or warranty.

Please keep us posted.

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[watersupply189]

Sorry to hear this.

Did you check to ensure the “black box” halves are securely together?

Sounds like they may have unplugged something there when removing the whole dash.


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

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