Em Bee Lover

Live in upper Midwest US where temps in winter are nasty. Rest function is nice, as the heat from the engine etc. is funneled through to the interior after the engine is shut down and you leave the vehicle. Keeps inside toasty for many minutes. Hit the tab, when ignition off and a red led would come on indicating it's working.

The function has quit working. No red indicator when tab is pushed up or down. Also don't feel warmth upon return. What could go wrong out of the blue?

Nothing should have tripped a fuse? The cabin filter was replaced about the time, as I recall, the Rest quit working. There should be no tie-in between the two, would you think?

Tracking the fuse is a pain. Not anxious to drive 40 miles each way and spend God knows how much at the dlrshp., if I can help it.

Any advice?

Thanks.

konigstiger

If the on-board power supply voltage is too low, the residual heat function is switched off automatically.

Em Bee Lover

I am not informed enough to know if the voltage is low. Does the power/voltage for Rest come from the main battery in engine compartment or the battery in the trunk area? Both?

Mine is a 2007 Launch. The engine compartment battery was replaced 11 months ago w/ an OEM MB labeled one, from my MB dlr. That should still be solid. If the constant voltage comes from the rear one, after ignition is off, then that may be the culprit. If it is, what others functions may be affected that are maintained by the rear battery when the ignition is off?

Thanks for your first reply.

konigstiger

Starter battery is located in engine compartment, onboard electrical system located in rear managed by control module to stabilize if necessary (e.g. consumer shutoff). Engine compartment battery provides the power for starting and supplies onboard electrical system when the rear battery is discharged (voltage < 9 V). Both batteries should have at least 12.2V. See attachment to check voltage.

konigstiger

Engine on - if voltage is less than 12.2 V for longer than 2 sec shutoff function activates (if voltage stabilizes at 12.2V consumers are reactivated in the reverse order).
Engine off - if the voltage is < 11.5 V for longer than 60 sec shutoff function activates (voltage stabilizes all the consumers are reactivated simultaneously).