Chevrolet Silverado / GMC Sierra. Manual - part 828
12
Perform the Line Pressure Check.
Is the line pressure within specification?
Go to Symptoms
- Automatic
Transmission
Go to Symptoms
- Automatic
Transmission
13
Inspect for the following unacceptable shift
pattern conditions:
No upshift or downshift
Only 1 or 2 forward ranges
No first range, second range, third range,
fourth range, or fifth range
Slipping
Non first range start
Did the vehicle exhibit any of these shift
pattern conditions?
Go to Symptoms
- Automatic
Transmission
Go to Step 14
14
Inspect for the following unacceptable range
performance conditions:
No PARK, REVERSE, or DRIVE
No engine braking
No gear selection
Incorrect gear selection
Did the vehicle exhibit any of these range
performance conditions?
Go to Symptoms
- Automatic
Transmission
System OK
15
Inspect for the following specific torque
converter conditions or TCC conditions:
Stuck ON or Stuck OFF
Early or late engagement
Incorrect apply or release
Soft or harsh apply
Clunk or shudder
No torque multiplication
Excessive slip
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
TRANSMISSION FLUID CHECK
COLD FLUID CHECK
The purpose of the cold check is to determine if the transmission has enough fluid to be operated
safely until a hot check can be made.
1. Bring the vehicle to a complete stop on a level surface using the service brakes.
2. Ensure that the engine is at low idle RPM (500-800 RPM).
3. With the service brakes applied, put the transmission in the P, PARK, position.
4. Engage the park pawl by slowly releasing the service brakes. The vehicle may move slightly
as the pawl engages.
5. Apply the parking brake and ensure it is properly engaged.
6. Run the engine for at least one minute. Apply the service brakes and shift to D, DRIVE,
then to N, NEUTRAL, and then shift to R, REVERSE, in order to fill the hydraulic system.
7. Ensure that the engine is at low idle RPM (500-800 RPM).
8. With the service brakes applied, put the transmission in the P, PARK, position.
9. Engage the park pawl by slowly releasing the service brakes. The vehicle may move slightly
as the pawl engages.
10. With the engine running, remove the fluid level indicator from the fill tube and wipe the
indicator clean.
Poor acceleration
Engine stalls
Did the vehicle exhibit any of these torque
converter or TCC conditions?
Go to Torque
Converter
Diagnosis
System OK
IMPORTANT: The fluid level rises as fluid temperature increases. DO NOT
fill above the COLD CHECK band if the transmission fluid is
below normal operating temperatures.
IMPORTANT:
If the fluid level is within the COLD CHECK band, the
transmission may be operated until the fluid is hot
enough to perform a HOT RUN check. If the fluid level is
not within the COLD CHECK band, add or drain as
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
11. Insert the fluid level indicator into the fill tube and remove. Check the fluid level reading.
Repeat the check procedure to verify the reading.
12. Perform a hot check at the first opportunity after the normal operating sump temperature of
71-93°C (160-200°F) is reached.
HOT FLUID CHECK
1. Operate the transmission in D, DRIVE, range until normal operating temperature is reached.
Normal operating temperature is any of the following:
Sump temperature 71-93°C (160-200°F)
Converter-out temperature 82-104°C (180-220°F)
If a transmission temperature gage is not present, check the fluid level when the engine
water temperature gage has stabilized and the transmission has been operated under
load for at least one hour.
2. Bring the vehicle to a complete stop on a level surface using the service brake.
3. Ensure that the engine is at low idle RPM, 500-800 RPM.
4. With the service brakes applied, place the transmission in the P, PARK, position.
5. Engage the park pawl by slowly releasing the service brakes. The vehicle may move slightly
as the pawl engages.
6. Apply the parking brake and ensure it is properly engaged.
7. With the engine running, remove the fluid level indicator from the fill tube and wipe the
indicator clean.
necessary to bring it to the middle of the COLD CHECK
band.
Always check the fluid level at least twice using the
procedure described above. Consistent readings are
important in order to maintaining proper fluid level. If
inconsistent readings persist, inspect the transmission
vent assembly to be sure that it is clean and unclogged.
If readings are still inconsistent, contact your nearest
Allison distribution or dealer.
IMPORTANT: The fluid must be hot to ensure an accurate check. The fluid
level rises as temperature increases.
IMPORTANT: Always check the fluid level at least twice using the
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
8. Insert the fluid level indicator into fill the tube and remove. Check fluid level reading.
Repeat the check procedure to verify the reading.
9. If the fluid level is not within the HOT RUN band, add or drain as necessary to bring the
fluid level to within the HOT RUN band.
FLUID INSPECTION
1. Examine the drained fluid for evidence of dirt.
2. Examine the drained fluid for evidence of water. Obvious water contamination of the
transmission fluid or transmission fluid in the cooling water from the heat exchanger
indicates a leak between the water and fluid areas of the cooler. Inspect and pressure test the
cooler to confirm the leak. Replace leaking coolers.
procedure described above. Consistent readings are
important to maintaining proper fluid level. If inconsistent
readings persist, inspect the transmission vent assembly to
be sure it is clean and unclogged. If readings are still
inconsistent, contact your nearest Allison distribution or
dealer.
IMPORTANT: Safe operating level is within the HOT RUN band on the fluid
level indicator. The width of the HOT RUN band represents
approximately 1.0 liter (1.06 quarts) of fluid at normal
operating sump temperature.
IMPORTANT: Transmission fluid must be changed whenever there is
evidence of dirt or a high temperature condition. High
temperature causes the transmission fluid to be discolored
or to have a strong odor. Local conditions, severity of
operation, or duty cycle may require more or less frequent
fluid or filter change intervals.
IMPORTANT: Cooler water may be contaminated by engine oil if an engine
oil cooler is present; be sure to locate the correct source of
cooler water contamination.
NOTE:
Engine coolant in the transmission hydraulic system requires
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado