Medallion gauges-

[Kelley1]

Trying to trouble shoot my gauge issues, I have emailed and have a call into Medallion tech support but haven't heard back from them yet. Hoping someone here has knowledge on the can bus system.  I have a 2005 lsv23. with the 3 5" gauges. This is a can bus system. The 4 in 1 gauge has the oil, volt, temp and fuel. The speedo has the needle and lcd readout. The tach has the needle and perfect pass made into it. I can perform the gauge sweep and every gauge  works. The fuel gauge does work with key on. The volt, temp and oil psi will not work with key on. I can read rpm and speed through the perfect pass. The speedo. needle will sweep during test, but will not move when turning the paddle wheel. The wiring to the gauges are blue, yellow, gray/black, red white. I have 7 volts on the red/white, gray/black is ground, blue is lights, yellow is can bus. I have 12 volts key on loaded at the MMDC out connector and good grounds, back probing into the connector. Can the speedo. and 4/1 gauge pass the sweep test and still be bad? Also the lcd will flash ecu. I have replaced the MMDC, same result.

[Eagleboy99]

https://cdn.bakesonline.com/media/resourcelibrary/MedallionII_Troubleshoot.pdf  Some is sure to correc tme if I am wrong, but IIRC Medallion is not a pure Canbus end-to-end system. The ECM sends data over a CAN bus to the MMDC which converts it to a different signal that the gauges use.  And you should almost always start by cleaning and resetting every connector you can find.
 

[justgary]

The tach, temperature, and oil pressure data comes through the cannon plug on the side of the engine.  Remove it and inspect it for pushed pins, etc. and make sure it is making good contact.

[jgates237]

On 10/16/2020 at 11:57 AM, Kelley1 said:

Trying to trouble shoot my gauge issues, I have emailed and have a call into Medallion tech support but haven't heard back from them yet. Hoping someone here has knowledge on the can bus system.  I have a 2005 lsv23. with the 3 5" gauges. This is a can bus system. The 4 in 1 gauge has the oil, volt, temp and fuel. The speedo has the needle and lcd readout. The tach has the needle and perfect pass made into it. I can perform the gauge sweep and every gauge  works. The fuel gauge does work with key on. The volt, temp and oil psi will not work with key on. I can read rpm and speed through the perfect pass. The speedo. needle will sweep during test, but will not move when turning the paddle wheel. The wiring to the gauges are blue, yellow, gray/black, red white. I have 7 volts on the red/white, gray/black is ground, blue is lights, yellow is can bus. I have 12 volts key on loaded at the MMDC out connector and good grounds, back probing into the connector. Can the speedo. and 4/1 gauge pass the sweep test and still be bad? Also the lcd will flash ecu. I have replaced the MMDC, same result.

Good luck with Medallion. I tried endlessly for a few years to rectify delamination (bubbles) with our touch screens. They never answered once. Ended up getting a replacement from a Bu dealership in the southwest. Fairly cheap item that cost us in need over $800.