SB-10057673-8478
File in Section:

Service Bulletin

Bulletin No.:
Date:

PIP4869D
March, 2015

PRELIMINARY INFORMATION
Subject:

(EREV) Reduced Propulsion Power While Driving in Mountains

Models:

2011-2015 Chevrolet Volt
2014-2015 Cadillac ELR
2012-2015 Opel Ampera
This PI was superseded to update Model Years. Please discard PIP4869C.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern
A common DIC message seen by customers driving in the mountains is “Propulsion Power is Reduced.” It is
recommended that customers enter Mountain Mode on the Volt when the vehicle has a full charge if their travel plans
involve mountainous driving before the next charge event. This message may appear while severe highway grades,
even in Mountain Mode, such as driving on Interstate 70 in Colorado. This is considered normal operation.
It is possible that this message could appear in Normal or Sport mode in non-mountainous terrain, typically with
aggressive driving. When this message appears with aggressive driving, the battery reserve has been depleted.
This message may also appear on start up if the battery is at or below -15 degrees C (5 degrees F), possibly from
the vehicle sitting outside unplugged in the winter. This will be accompanied by higher engine speeds to compensate
for the low battery power
Important: This message comes on any time the battery is reporting less than 35kW of power available for any
reason. This message will NOT require service by a dealer unless the Propulsion Power Reduced message is
accompanied by a Malfunction Indicator Light (Check Engine Light)

Recommendation/Instructions
Below is an explanation of Mountain mode that goes beyond the owner’s manual

MOUNTAIN MODE
If your destination takes you over mountain passes in extended range driving, Volt engineers created
Mountain Mode.
To enter Mountain Mode, press the Drive Mode button three times after you unplug your Volt or 30 minutes before
you start climbing the grade.
Mountain Mode reserves some battery charge to use later during the climb. If you enter Mountain Mode below 4 bars
of battery charge, the engine will run at a higher speed to build the battery buffer.
If you enter Mountain Mode above 4 bars of battery charge, the estimated electric range will adjust accordingly.
If Mountain Mode is not selected in these severe conditions, you may experience reduced propulsion power and
higher engine speed.
The Volt will continue to drive, but the vehicle speed may be reduced until the engine can recover the battery state of
charge to a normal level.
Each time you power on your Volt, it will return to Normal Mode, which maintains a smaller battery buffer suitable for
normal driving.

WHEN TO USE MOUNTAIN MODE
Mountain Mode is primarily needed for prolonged grades at high vehicle speed, as found in the Western United
States. Refer to the owner’s manual for more information.

Mountain Mode should be selected at the beginning of the drive; ideally as the vehicle is unplugged from charging. If
a trip through the mountains or very hilly terrain is planned, Mountain Mode should be selected as early as possible
(at least 20-25 minutes before reaching the bottom of the mountain). This will ensure that vehicle performance will
not be affected by mountainous terrain.

WHAT TO EXPECT ONCE MOUNTAIN MODE IS SELECTED
After Mountain Mode is engaged the following vehicle operation should be expected:
When Mountain Mode
is Engaged

Battery Charge Level

Expected Engine
Operation

Vehicle Performance Characteristics

After a full charge
before shifting out
of park

Full or close to full

No engine operation
until EV range is
depleted

Vehicle performance unchanged. Estimated EV
range decrease

While driving

Half battery

No engine operation
until EV range is
depleted

Vehicle performance unchanged. Estimated EV
range decrease

While driving

Low battery (less than
4 bars)

Engine will start soon
after Mountain Mode is
engaged

Engine may run aggressively to build battery
buffer*

While driving

Zero battery charge/
range extended mode

Engine will run
aggressively to build
battery buffer

In cases when the vehicle is already climbing
grades the vehicle may slow down and a
message stating “Propulsion Power Reduced” will
be displayed to the driver*

Not selected

Zero battery charge/
range extended mode

Engine will run
aggressively to climb
grades

In cases when the vehicle is already climbing
grades the vehicle may slow down and a
message stating “Propulsion Power Reduced” will
be displayed to the driver*

Note: Driver may receive the “Propulsion Power Reduced” message in any mountainous terrain when an
appropriate battery buffer cannot be built BEFORE reaching the grade. The ideal time to select Mountain Mode is
when the vehicle is unplugged or 20-25 minutes BEFORE reaching the bottom of the mountain.

PROPULSION POWER REDUCED” MESSAGE
The message comes on any time the battery is reporting less than 35kW of power available for any reason.
The Propulsion Power Reduced message can occur when driving in mountainous terrain WITHOUT using Mountain
Mode. This is normal operation to protect the vehicle’s propulsion battery. The vehicle does NOT need to be taken to
a dealer unless the Propulsion Power Reduced message is accompanied by a Malfunction Indicator Light (Check
Engine Light).
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is
resolved without completing every step, the remaining steps do not need to be performed.