The 1998 GMC 1500, more commonly known as the GMC Sierra, is part of a family of light-duty trucks and was actually released in 1999. The trucks have either a Vortec 4300 or LU3 6 cylinder engine. In either case, the windshield-washer pump is the same. The windshield-washer pump forces the windshield-washer solvent through the windshield-washer system. The solvent sprays onto the windshield, and cleans the glass in conjunction with the windshield-washer blades. The windshield-washer pump is attached to the windshield-washer reservoir, which sits in front of the fender of the passenger-side tire. If the pump is damaged, perhaps in an auto accident, it should be replaced. Fortunately, replacing the pump is a straightforward process and can be finished within an hour.
Remove part of the front passenger-side fender by taking off two of the bolts attaching the fender to the vehicle. Use your socket wrench to remove these bolts, which sit horizontally in the wheel well.
Pull the fender in toward the wheel and tuck it out of the way when the bolts are removed. This reveals the windshield-washer reservoir and the washer pump attached to it.
Pull off the windshield-washer pump connector by gripping it and pulling firmly upward. The connector brings electrical power to the pump; a small black cylinder crouched against the white body of the reservoir. Pull firmly, but do not jerk the connector off or you may break it.
Pull the washer hose off the nipple of the washer pump. The hose and nipple are located opposite the connector on the washer pump.
Pull the pump off of the washer reservoir. The shape of the washer reservoir itself holds the pump in place. Use some force to pull the pump straight out of the reservoir.
Use your pick to pry off the plastic washer-pump grommet mounted where the pump was attached to the washer reservoir. Stick the head of the pick under the flange, or lip, of the grommet, and pry the grommet off in one swift motion.
Compare the old windshield washer pump to the new one, checking that the height and girth, the number of pins in the socket for the connector, and the location of the nipple are all the same.
Insert the grommet from the new pump into the washer reservoir. Spray some WD40 onto the grommet and insert the washer pump over the grommet, snapping the pump underneath the tabs of the washer reservoir.
Reattach the hose to the nipple of the pump and the connector to the socket of the pump. Unfold the fender and replace the two bolts you removed earlier.
