MACS Service Reports - 2016 - OCT5

proved fuel economy and EV range. This system will
operate if the ECO button had been pressed, and so it
would result in the system taking much longer to cool
down the passenger cabin. Therefore, if the complaint
is that the cooldown was inadequate, that's one possibility to check, in addition to the obvious possible
issue of limited remote operation because of depleted
capacity in the battery pack.
The ECO mode sets the following limitations on
remote A/C or pre-heating operation, basically to reduce power consumption:
Inside/outside air switch: automatically switches
the air inlet to the internal air circulation when the
outside temperature is equal to or higher than a predetermined temperature.
Blower speed level: sets the blower in an AUTO
mode that's lower than normal.
PTC (Power Temperature Coefficient) heater: this is
the quick electric heater for warming up the cabin. In
remote it does not operate.
Heating restriction: it changes the heater air outlet
temperature by turning the ECO mode switch on and
off during heating, which increases the amount of engine-off heater time when the ECO mode is in the on
position.
Compressor speed restriction. Basically the same
idea as heating restriction, but during the air conditioning season. It restricts the maximum speed of the
electric A/C compressor, so there's less cooling but
also less power draw of course. ■

techinfo.toyota.com

capacity in the high voltage battery pack to run the
A/C for about 10 minutes, and still be able to subsequently start and run the engine, of course. If the
vehicle is plugged in to 120 V or 240 V household current, the system will take the charging into account,
and so the 10 minutes of remote A/C time will not be
an issue. But you (and the owner) should understand
that the use of battery pack energy vs. plug-in current
does set limits on how comfortable the car interior can
become on days with extreme temperatures - the interior may not get very cool.
If the remote feature is being run from a smartphone, there may be an inclination to think any lack of
function is with the system, particularly if the remote
works from the keyfob. However, the smartphone
app is still just an app, with limitations of its own,
and the fact that the request must go through a Toyota
server in a service center, to the vehicle's telematics
module (FIG. 9).
If the main body computer, which monitors all the
needed operating conditions, decides any one is not
met, it will not allow the remote A/C to run. Important: that includes the obvious limitation that it's been
at least 10 minutes since the remote system last run.
So if you kept trying to get it to activate and didn't allow at least 10 minutes, that part of the remote A/C algorithm would keep throwing you a diagnostic curve,
even when the system is plugged in.
A related factor is that the Prius PHV has an "ECO"
mode, which reduces A/C and heating output for im-

Figure 9: DCM telematics module is installed in the control stack on the Prius plug-in hybrid.

October 2016

MACS Service Reports

http://www.techinfo.toyota.com

Table of Contents for the Digital Edition of MACS Service Reports - 2016