1999 GMC SONOMA turn signal

6-39
4. Turn the bulb assembly counterclockwise to
remove it.
5. Put the new bulb assembly into the headlamp
assembly and turn it clockwise until it is tight.
6. Plug in the electrical connector.
7. Put the headlamp lens assembly back into the
vehicle. Install the two retaining clips.
One-Piece Front Turn Signal
Lamp Assembly
1. Remove the headlamp assembly as shown under
ªOne
-Piece Composite Headlamp Systemº earlier in
this section.
2. Twist the bulb socket
counterclockwise to
remove it from the
headlamp assembly.
3. Pull the bulb straight out to remove it from
the socket.
4. Push the new bulb into the socket until it snaps
into place.
5. Put the bulb socket into the lamp assembly and twist
it clockwise until it is tight.
6. Put the headlamp assembly back into the vehicle.
Install the two retaining clips.

6-40 Two-Piece Front Turn Signal
Lamp Assembly
1. Remove the headlamp assembly as shown under
ªTwo
-Piece Composite Headlamp Systemº earlier in
this section.
2. Locate the locking tabs
on the assembly.
Squeeze the tabs
together and push that
end of the assembly out
while holding the tabs.
The assembly will
swing out.
3. Unplug the electrical connector.
4. Turn the harness bulb socket counterclockwise to
remove it. Pull the bulb straight out to remove it
from the socket.
5. Push the new bulb into the socket until it snaps
into place.
6. Put the socket into the lamp assembly and turn it
clockwise until it is tight.
7. To replace the assembly, snap the outboard end of
the lamp assembly back into the vehicle. Then swing
the assembly in and snap it into place.
8. Replace the headlamp assembly. Install the two
retaining clips.

6-64
Fuse/Circuit
Breaker Usage
3 Cruise Control, Body Controls
TBC, Cruise Module,
Cruise Switch
4 Gages, Body Controls TBC,
Instrument Panel Cluster,
B+ Power
5 Parking Lamps, Power Window
Switch, TBC, Ashtray Lamp
6 Not Used
7 Headlamp Switch, Body Controls
TBC, Headlamp Relay
8 Courtesy Lamps, Inadvertent
Power Relay
9 HVAC Control Head
10 Turn Signal
11 Instrument Panel Cluster,
Engine Controls
12 Interior IlluminationFuse/Circuit
Breaker Usage
13 Auxiliary Power
14 Power Locks
15 4WD Switch, Engine Control
(VCM, PCM, Transmission)
16 Supplemental Inflatable Restraint
17 Front Wiper
18 Not Used
19 Radio Battery
20 Not Used
21 HVAC I, HVAC Control Head,
HVAC Devices
22 Anti
-Lock Brakes
23 Rear Wiper
24 Radio, Ignition

6-65 Engine Compartment Fuse Block
The fuse block is under the hood on the driver's side of
the engine compartment.
Remove the cover by turning the fastener
counterclockwise. To reinstall the fuse panel cover, push
in and turn the fastener clockwise.Name Usage
TRL TRN Not Used
TRR TRN Not Used
TRL B/U Not Used
VEH B/U Vehicle Back
-Up Lamps
RT TURN Right Turn Signal Front
LT TURN Left Turn Signal Front
HDLP W/W Not Used
(Continued)

6-66
Name Usage
LT TRN Left Turn Signal Rear
RT TRN Right Turn Signal Rear
RR PRK Right Rear Parking Lamps
TRL PRK Not Used
LT HDLP Left Headlamp
RT HDLP Right Headlamp
FR PRK Front Parking Lamps
INT BAT I/P Fuse Block Feed
ENG I Engine Sensors/Solenoids, MAF,
CAM, PURGE, VENT
ECM B Engine Control Module, Fuel Pump
Module, Oil Pressure
ABS Anti
-Lock Brake System
ECM I Engine Control Module Injectors
BTSI Automatic Transmission Shift Lock
Control System
B/U LP Back
-Up Lamps
A/C Air Conditioning
W/W PMP Not Used
HORN Horn
IGN B Column Feed, IGN 2, 3, 4
RAP Retained Accessory Power
LD LEV Not UsedName Usage
OXYSEN Oxygen Sensor
IGN E Engine
MIR/LKS Mirrors, Door Locks
FOG LP Fog Lamps
IGN A Starting and Charging IGN 1
STUD #2 Accessory Feeds, Electric Brake
PARKLP Parking Lamps
LR PRK Left Rear Parking Lamps
IGN C Starter Solenoid, Fuel Pump,
PRNDL
HTDSEAT Not Used
HVAC HVAC System
TRCHMSL Not Used
RRDFOG Not Used
TBC Truck Body Computer
CRANK Clutch Switch, NSBU Switch
HAZLP Hazard Lamps
VECHMSL Vehicle Center High
-Mounted
Stoplamp
HTDMIR Heated Outside Mirrors
ATC Transfer Case (Four
-Wheel Drive)
STOPLP Stoplamps
RR W/W Not Used

6-67
Replacement Bulbs
Lamps Quantity Number
Halogen Headlamps, Composite Low
-Beam2 9006 HB4
Halogen Headlamps, Composite High
-Beam2 9005 HB3
Tail and Stoplamps 2 3057
Front Sidemarker Lamps 2 194
Front Turn Signal Lamps 2 3157NA
Center High
-Mounted Stoplamp2 577
Capacities and Specifications
Please refer to ªRecommended Fluids and Lubricantsº in the index for more information. See refrigerant change label
under the hood for charge capacity information and requirements.
Engine 2200 L4 ªVORTECº 4300 V6 ªVORTECº 4300 V6
Type L4 V6 V6
VIN Code 4,5 X W
Firing Order
1
-3-4-21-6-5-4-3-21-6-5-4-3-2
Horsepower (T Series) N/A 180 at 4,400 rpm 190 at 4,400 rpm
Horsepower (S Series) 120 at 5,000 rpm 175 at 4,400 rpm 180 at 4,400 rpm
Thermostat Specification
195
F (91
C) 195
F (91
C) 195
F (91
C)
Spark Plug Gap 0.040 inches
(1.01 mm)0.060 inches
(1.52 mm)0.060 inches
(1.52 mm)