trip computer - battery terminals and aftermarket installation - question . . .

[tvmaster]

We all know about the trip computer, and how you can remove the OEM radio while in ACC ignition mode, and then the last trip computer function (miles remaining, for eg.) will remain visible until the next time the battery is disconnected.

But

when you are changing your radio, your supposed to disconnect the battery before proceeding, thereby killing the trip computer display.

How can we have our cake and eat it too, essentially keeping the trip computer's single function without jeopardizing the unit about to be installed? I got a suggestion from another forum, but wondered if anyone here had an idea also.

What is the point in removing the (-) battery terminal? If you connect the ground of the incoming nav units harness, will that suffice?

[sas]

The harm from such disconnection happens when the ground is disconnected earlier than supply voltages and remaining loads. Therefore you can install a second ground wire connected to the head unit. This ground wire have to be disconnected after was disconnected the head unit.In other words any manipulations with connector have to be done with connected additional ground.Or try to disconnect the stock unit with switched off ignition and then removed ROOM fuse.Seems to me it should work too . Just enable the ignition to check that trip computer does't dissapear.Installation of aftermarket unit you can do in reverse order.Install- Set the Room fuse-enable ignition.