How to retain left side trip computer LCD display with aftermarket head unit - help

[tvmaster]

I have a 2007 MZ3 GT with auto AVAC. If I change the stereo, I know I retain the HVAC display, as it has a seperate harness now (2006 and up?).

However, there's a trick to retain at least ONE, static trip computer function, but I can't find it. If memory serves, you have to set the trip computer to the function you want (clock, for example), remove the factory radio while the ignition is hot, and then connect the new headunit (in this case, a Pioneer).

Does that sound correct? What worries me is disconnecting and connecting things while the ignition is turned on - any suggestions?

[sas]

Look at this problem with other logic. After you reconnect the battery, all these modules, connected to the low speed CAN, have no default settings and are silent.To be more correct, the HVAC settings are remaining because the HVAC control module starts to send the data after you make any changes of climate control settings.Similar picture with the trip computer. by pressing the stock HU button you make the trip computer to awake, and it will send the data until you disconnect the battery again.

[-cj-]

Unplugging a device is safe, plugging something in while the car is powered, is not safe. Because you aren't using hot swappable power adapters, the risk of you plugging the power adapter on an angle and enabling certain pins and not others means you can fry something. Besdies the aftermarket radio doesn't tie into the CAN bus, so plugging it in doesn't do anything. I think you are on the right track with setting the stock HU and unplugging it.

[tvmaster]

Unplugging a device is safe, plugging something in while the car is powered, is not safe. Because you aren't using hot swappable power adapters, the risk of you plugging the power adapter on an angle and enabling certain pins and not others means you can fry something. Besdies the aftermarket radio doesn't tie into the CAN bus, so plugging it in doesn't do anything. I think you are on the right track with setting the stock HU and unplugging it.

so, while ignition is hot, set stock HU's trip computer, remove it, and then turn off ignition BEFORE connecting the Pioneer? Worth a try - I'd like to NOT fry my new deck :)

[sas]

You have to disconnect the stock HU with enabled ignition ,to not allow to shut off the trip computer when you switching the car off. The Pioneer can be connected with disabled power. Though, not tried it , but I think, even stock unit can be disconnected with disabled ignition.