1999 GMC SONOMA automatic transmission

7-44
Automatic Transmission Check
Check the transmission fluid level; add if needed. See
ªAutomatic Transmission Fluidº in the Index. A fluid
loss may indicate a problem. Check the system and
repair if needed.
Hydraulic Clutch System Check
Check the fluid level in the clutch reservoir. See
ªHydraulic Clutch Fluidº in the Index. A fluid loss in
this system could indicate a problem. Have the system
inspected and repaired at once.
At Least Four Times a Year
Tailgate Lubrication Service
Lubricate tailgate latch bolt, handle assembly pivot points,
and hinges with lubricant recommended in Part D.
At Least Once a Year
Key Lock Cylinders Service
Lubricate the key lock cylinders with the lubricant
specified in Part D.
Body Lubrication Service
Lubricate all body door and fuel door hinges, latches
and locks including the glove box, console doors, the
body hood, secondary latch, pivots, spring anchor,
release pawl, and any moving seat hardware. Lubricate
the hood safety lever pivot and prop rod pivot. Part D
tells you what to use. More frequent lubrication may be
required when exposed to a corrosive environment.

7-45
Starter Switch Check
CAUTION:
When you are doing this check, the vehicle could
move suddenly. If it does, you or others could be
injured. Follow the steps below.
1. Before you start, be sure you have enough room
around the vehicle.
2. Firmly apply both the parking brake (see ªParking
Brakeº in the Index if necessary) and the regular brake.
NOTE: Do not use the accelerator pedal, and be
ready to turn off the engine immediately if it starts.
3. On automatic transmission vehicles, try to start the
engine in each gear. The starter should work only in
PARK (P) or NEUTRAL (N). If the starter works in
any other position, your vehicle needs service.
On manual transmission vehicles, put the shift lever
in NEUTRAL (N), push the clutch down halfway
and try to start the engine. The starter should work
only when the clutch is pushed down all the way to
the floor. If the starter works when the clutch isn't
pushed all the way down, your vehicle needs service.Automatic Transmission Shift Lock Control
System Check
CAUTION:
When you are doing this check, the vehicle could
move suddenly. If it does, you or others could be
injured. Follow the steps below.
1. Before you start, be sure you have enough
room around the vehicle. It should be parked on a
level surface.
2. Firmly apply the parking brake (see ªParking Brakeº
in the Index if necessary).
NOTE: Be ready to apply the regular brake
immediately if the vehicle begins to move.
3. With the engine off, turn the key to the RUN
position, but don't start the engine. Without applying
the regular brake, try to move the shift lever out of
PARK (P) with normal effort. If the shift lever
moves out of PARK (P), your vehicle needs service.

7-46
Ignition Transmission Lock Check
While parked, and with the parking brake set, try to turn
the ignition key to LOCK in each shift lever position.

With an automatic transmission, the key should turn
to LOCK only when the shift lever is in PARK (P).

With a manual transmission, the key should turn to
LOCK only when you press the key release button.
On all vehicles, the key should come out only in LOCK.
Parking Brake and Automatic Transmission
PARK (P) Mechanism Check
CAUTION:
When you are doing this check, your vehicle
could begin to move. You or others could be
injured and property could be damaged. Make
sure there is room in front of your vehicle in case
it begins to roll. Be ready to apply the regular
brake at once should the vehicle begin to move.
Park on a fairly steep hill, with the vehicle facing
downhill. Keeping your foot on the regular brake, set the
parking brake.

To check the parking brake's holding ability:
With the engine running and transmission in
NEUTRAL (N), slowly remove foot pressure from
the regular brake pedal. Do this until the vehicle is
held by the parking brake only.

To check the PARK (P) mechanism's holding ability:
With the engine running, shift to PARK (P).
Then release the parking brake followed by the
regular brake.
Underbody Flushing Service
At least every spring, use plain water to flush any
corrosive materials from the underbody. Take care to
clean thoroughly any areas where mud and other debris
can collect.

7-50
USAGEFLUID/LUBRICANT
Manual
Transmission
with L4 EngineFriction Modified Synchromesh
Transmission Fluid (GM Part
No. 12377916).
Automatic
TransmissionDEXRON
-III Automatic
Transmission Fluid.
Key Lock
CylindersMulti-Purpose Lubricant,
Superlube
(GM Part
No. 12346241 or equivalent).
Chassis
LubricationChassis Lubricant (GM Part
No. 12377985 or equivalent) or
lubricant meeting requirements of
NLGI # 2, Category LB or GC
-LB.
Front
Wheel BearingsWheel Bearing Lubricant meeting
requirements of NLGI # 2,
Category GC or GC
-LB (GM Part
No. 1051344 or equivalent).
USAGEFLUID/LUBRICANT
Front and Rear
Axle (Standard
Differential)SAE 80W-90 Axle Lubricant
(GM Part No. 1052271
or equivalent).
Rear Axle
(Locking
Differential)Axle Lubricant; use only GM
Part No. 1052271. Do not add
friction modifier.
Automatic
Transfer CaseAUTO-TRAK II Fluid
(GM Part No. 12378508).
Transfer Case
Shift LeverChassis Lubricant (GM Part
No. 12377985 or equivalent) or
lubricant meeting requirements of
NLGI #2, Category LB or GC
-LB.
Rear Driveline
Center Spline
and Universal
JointsChassis Lubricant (GM Part
No. 12377985 or equivalent) or
lubricant meeting requirements of
NLGI # 2, Category LB or GC
-LB.