1993 GMC SIERRA Owners Manual

Fender Marker Lights
I
1. Remove the screws and take the lens assembly out of the fender.
2. Turn the bulb socket counterclockwise and remove it from the lens
3. Pull the bulb straight out of the socket.
4. Put a new bulb into the socket and push it in until it is tight.
5. Put the socket back into the lens assembly and turn it clockwise to
6. Replace the lens and tighten the screws.
assembly.
tighten it.
PO248
6-59
ProCarManuals.com

Service & Appearance Cam
Tailgate Marker Lights
PO249
1. Use a screwdriver to gently pry the lenslbulb assembly from the lens
2. Unplug the the lenslbulb assembly at the connecter wire.
3. Plug in a new lendbulb assembly and push the connecter wire i\
nto the
4. Snap the lenslbulb assembly into the lens holder.
holder.
hole in the tailgate.
Roof Marker Lights
6-60
ProCarManuals.com

1. Remove the screws and lift off the lens.
2. Pull the bulb straight out of the socket
3. Put a new bulb into the socket and push it in until it is tight.
4. Replace the lens and tighten the screws.
Cargo Light
, .. .....
PO250
1. Remove the screws and lift off the lens.
2. Pull the old bulb straight out of the socket
3. Put a new bulb into the socket and push it in until it is tight.
4. Replace the lens and tighten the screws.
6-61
ProCarManuals.com

Service & Appearance Care
Rear Lights, Pickup Models
I
i
1. Open the tailgate.
2. Remove the two rear light assembly screws near the tailgate la\
tch and
pull out the light assembly.
u PO496
3. Remove the screws from the bulb retainer and take it off the light
4. Pull the old bulb straight out of the socket
assembly.
5. Put
in a new bulb and push it in until it is tight.
6-62
ProCarManuals.com

6. Replace the bulb retainer.
7. Replace the rear light assembly and tighten the screws.
8. Close the tailgate.
Sear Lights, Chassis Cab Models
U
1. Using your hands, peel the rubber seal away from the lens.
I
PO497
2. Lift the lens off the light assembly.
3. Slide the socket out of the light assembly
6-63
ProCarManuals.com

Service & Appearance Care
4. Push in gently on the bulb, turn it counterclockwise and remove it from
the socket.
5. Put in a new bulb and, pushing in gently, turn it clockwise until it is
tight.
6. Put the socket back in the light assembly and replace the lens and lens
seal.
Fuses and Circuit Breakers
The wiring circuits in your vehicle are protected from short circuits by a
combination of fuses, circuit breakers, and fusible thermal links in the wiring
itself. This greatly reduces the chance of fires caused by electrical problems.
See “Fuses and Circuit Breakers’’ in the Index for more information.
Headlights
The headlight wiring is protected by a circuit breaker in the light switch. An
electrical overload will cause the lights to go on and
off, or in some cases to
remain
off. If this happens, have your headlight wiring checked right away.
Windshield Wipers
The windshield wiper motor is protected by a circuit breaker a\
nd a fuse. If
the motor overheats due
to heavy snow, etc., the wiper will stop until the
motor cools.
If the overload is caused by some electrical problem and not
snow, etc., be sure to get it fixed.
Power Windows and Other Power Options
Circuit breakers in the fuse panel protect the power windows and other power
accessories. When the current load is too heavy, the circuit breaker opens
and closes, protecting the circuit until the problem is fixed or goes away.
Trailer Wiring Harness
The optional seven-wire trailer wiring harness is protected by an in-line fuse
in the battery feed wire. This fuse is near the junction block. See “Trailer
Wiring Harness” in the Index for more information.
6-64
ProCarManuals.com

Fuse Block
K2644
The fuse block is in the instrument panel on the driver’s side.
You can remove fuses with a fuse extractor,
if you have one. To remove
fuses
if you don’t have one, hold the end of the fuse between your thumb
and index finger and pull straight out.
Be sure
to use the correct fuse. If you ever have a problem on the road and
don’t have a spare fuse, you can “borrow’’ one of the correct value. Just pick
some feature
of your vehicle that you can get along without-like the radio or
cigarette lighter-and use its fuse,
if it is of the value you need. Replace it
as soon as you can. See “Fuses and Circuit Breakers” in the Index for more
information.
Exhaust System
To help prevent damage to your exhaust system, do not continue to drive
your vehicle
if you notice:
Engine misfiring
Loss of performance
Other unusual operating conditions
Have your engine and exhaust system serviced regularly.
Three- Way Cataiytic Converter
Your vehicle’s three-way catalytic converter is designed to reduce the
pollutants in your vehicle’s exhaust. Use only unleaded fuel in your vehicle.
If
6-65
ProCarManuals.com

you use leaded fuel, you could damage your three-way catalytic converter,
and other engine components.
Computer Command Control System (All TBI equipped
vehicles and diesel engine vehicles below
8,500 lbs. GVWR)
Gasoline Engines
This system has an oxygen (OS) sensor that helps keep your engine’s air-fuel
mixture at a proper level. Use only unleaded fuel in your veh\
icle.
If you use
leaded fuel, you could damage your oxygen
(OS) sensor and three-way
catalytic converter.
Diesel Vehicles Below 8,500 LBS. GVWR
This system monitors engine speed and throttle position. It adj\
usts exhaust gas recirculation to limit emissions.
The Malfunction Indicator Lamp
(SERVICE ENGINE SOON) on your
instrument panel lets you know when your emission control syste\
m needs
service. The light will come on briefly when you start your e\
ngine to let you
know that the system is working. If
it does not come on when you start your
engine, or
if it comes on and stays on while you’re driving your system may \
need service. Your vehicle should still be driveable, but you should have your
system serviced right away.
Secondary Air Injection (AIR) System
You may have this system. It lets you know if your engine control module,
wiring harness or solenoid need service.
If the Malfunction Indicator Lamp
(Service Engine Soon) comes on, you need service.
6-66
ProCarManuals.com