MCi Crusader II 1989 Maintenance Manual page 326

Date
1-1-89
Page
9-18
MC-9 MAINTENANCE MANUAL
TROUBLE
CRUISE CONTROL WILL NOT SET
CAUSE
1. Coach speed was below 20 mph or above the preset top limit
when Set switch was depressed.
2. Cruise control Power switch not ON.
3. Defective Power switch or wiring to or from Power switch.
Check for presence of 24
voe
AT SWITCH TERMINALS AS
REQUIRED. Replace switch or wiring if defective.
4. Seti Resume switch defective or grounded, or defective wiring
to or from switch. Check for presence of 24
voe
as required at
connector 1 when switch is held in SET and RESUME positions.
Replace switch or wiring if defective.
5. Defective solenoid assembly, air pressure reducing valve, or
wiring. Perform the following tests:
a. Build coach air system pressure to governor cutout and
secure in place by means other than air brakes.
b. Turn off cruise control.·
c. Disconnect wiring connector 4.
d. Apply+24
voe
tosocket1 and-24VOCtopin4whilemaking
observation in step 5.
e. Listen for audible click and .sound of air escaping from
exhaust port on exhaust solenoid. If exhaust is heard, pro-
ceed to step 7.
f. If no clicks are heard, solenoid assembly must be replaced.
g. If solenoid clicks and no air is exhausted, check for presence
of 60 psi (414 kPa) air pressure at the solenoid. If air pressure
check is satisfactory, replace exhaust solenoid. If 60 psi is not
present. the reducing valve or connecting air lines must be
repaired or replaced.
6. Defective inversion valve or air cylinder. Per1orm the following
tests:
a. Apply +24 \(DC to pins 3 and 4 and -24
voe
to sockets 1 and
2 of connector 4 while making observation in step 2.
b. Listen for audible click and observe movement of throttle
cable at air cylinder.
c. If throttle does not move. check for air pressure at fittings B
and C (solenoid assembly and air cylinder).
d. If air pressure is present at 8 but not at C, inversion valve or
connecting air lines must be repaired or replaced.
e. If no air pressure is present at B, replace solenoid assembly.
f. If air pressure is present at C, check for damage to air
cylinder and/or throttle cable. Check for cable binding and
repair as required. Check resistance between sockets of
connector 3, as shown in following chart
Socket
1 and 3
2and 3
1 and 2
Resistance
3600-4400 ohms
1080-1320 ohms
4320-5280 ohms
If these values are not obtained. replace air cylinder potentiom-
eter or repair potentiometer wiring as required.
7. Defective control module. Perform the following tests:
a. Turn cruise control system off.
b. Measure resistance between control module ground
wire
and coach ground. Measure resistance between socket 3 of
connector 3 and control module ground
wire.
In both cases
resistance should be 0. Replace control module if any resis-
tance is measured.