GMC 2001 Sierra 1500 Pickup Owner's Manual page 365

Checking the Fluid Level
Prepare your vehicle as follows:
D
Park your vehicle on a level place. Keep the
engine running.
D
With the parking brake applied, place the shift lever
in PARK (P).
D
With your foot on the brake pedal, move the shift
lever through each gear range, pausing for about
three seconds in each range. Then, position the
shift lever in PARK (P).
D
Let the engine run at idle for three minutes or more.
Then, without shutting off the engine, follow these steps:
1. The red transmission dipstick handle is located at the
rear of the engine compartment, on the passenger's
side. See "Engine Compartment Overview" in the
Index for further information on location. Flip the
handle up and then pull out the dipstick and wipe it
with a clean rag or paper towel.
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