Differential Lock Indicator Light; Reduced Engine Power Light; Daytime Running Lamps Indicator Light - GMC 2003 GMT560 T-Series Owner's Manual

Differential Lock Indicator Light

The light will come on momentarily during starting. If the
light fails to come on, have it repaired as soon as
possible so you will be aware when the lock system is
in use.

Reduced Engine Power Light

3-36
If your vehicle has this
feature, this light is located
in the center of the
instrument panel. The light
is on when the inter-axle
differential lock system
is in use.
If the check engine and
reduced engine power
lights are on, the throttle
may be disabled, and
a noticeable reduction in
the vehicle's performance
may occur.
If the reduced engine power light is on, but there is no
reduction in performance, proceed to your destination.
The performance may be reduced the next time
the vehicle is driven. The vehicle may be driven at a
reduced speed while the reduced engine power light is
on, but acceleration and speed may be reduced.
Anytime the check engine light stays on, the vehicle
should be taken to an authorized GM dealer as soon as
possible for service.
Daytime Running Lamps
Indicator Light
See Daytime Running Lamps under Exterior Lamps on
page 3-12 for further information.
When it begins to get dark, the DRL indicator light is a
reminder to turn on your headlamps.
This light is located on the
instrument panel cluster. It
goes on whenever the
Daytime Running Lamps
are on.