GMC 4000 Series Service Manual page 36

Figure 16— Separating Pum p from Motor
3. Remove washer pump attaching screw s, then
lift pump off wiper motor.
PUMP INSTALLATION (Figs. 15 and 16)
1. Place washer pump in position on wiper
motor making sure lever arm pin properly engages
four-lobe cam.
2. Secure pump to motor with two mounting
screw s.
3. Reconnect electric wiring.
4. Reconnect water hoses.
TROUBLESHOOTING WASHER PUMP
(Refer to Fig. 17)
On-Vehicle Check
1. If washer pumps continuously when wiper is
on, disconnect wiring from washer pump.
a. If pump shuts off, trouble is located in wir­
ing harness or dash switch.
b. If pump fails to shut off in Step a, remove
pump assembly from vehicle for further checking.
2. Check the following items if pump is in­
operative:
a. Reservoir contains water solution.
b. Hoses are not damaged and hose connec­
tions are tight.
c . Screen at end of jar cover hose is not plugged.
d. Electrical connections to washer pump and
dash switch are secure.
e. Nozzles are not plugged.
G M C S E R V I C E M A N U A L
motor only, then push washer button and listen for
"click" as washer solenoid pulls in. If no "click"
is heard, check for 12 volts at terminal No. 2 (fig.
17). No voltage indicates defective wiring. If "click"
is heard, proceed to Step 5.
connect a jumper wire from washer terminal No.
1 to ground (fig. 17) and operate wiper. If washer
relay "click" is heard and pump functions correctly,
a defective dash switch or an open circuit between
washer pump and dash switch is indicated - "No
Click" indicates an open pump solenoid.
for the soft clicking as the pump ratchet wheel is
rotated.
anism is faulty and should be removed from the
wiper motor and checked.
tion occurs, replace the valve assembly and re­
check pump.
INTAKE V A L V E
EXHAUST VALVE
GENERAL MAINTENANCE
3. If all items in Step 2 check out, start wiper
4. If correct voltage was found in Step No. 3,
5. If relay "click" is heard in Step 3, listen
a. If soft clicking is not heard, the pump mech­
b. If soft clicking is heard but no pumping ac­
PISTON
SP R IN G
AC TU ATO R PLATE
Figure 1 8 — W a sh e r Pum p Piston a n d V a lve Assem bly
Sec. 1
Page 29
ACTUATOR
PLATE T A N G
T-5881