Vehicle Speed Cannot Be Set - Mazda MX-5 1990 Workshop Manual

CRUISE CONTROL SYSTEM
T
TROUBLESHOOTING
Symptom: Vehicle speed cannot be set. (Cruise control unit will not hold vehicle speed.)
Note
• Before troubleshooting of the system, verify the following items:
1. Is system being correctly used by customer?
2. Is fuse OK?
Check the fuse. If the fuse is burned, replace it. Check the wire harness for a short circuit.
05UOTX-330
05UOTX-211
C
h f d b
05UOTX-212
05UOTX·213
Step 1
1. Turn the ignition switch ON.
2. Turn the cruise control main switch ON.
3. Check that the main switch indicator lamp comes ON.
4. If the lamp does not come ON, go to Step 2.
5. If the lamp comes ON, go to Step 3.
Step 2
1. Check continuity between terminals of the cruise control
main switch.
Position
Terminals
a
b d
f
g
h
Neutral
0- iD 0-
~
Off
0-
ro
0 0-
f-O
0-
f-O
On
0 -0
0--0:
Indicates continuity
2. If not as specified, replace the switch.
3. If the switch is OK, repair the wire harness.
(METER 10A fuse - Cruise control main switch - Ground)
Step 3
1. Measure the voltage at the following terminal-wires of the
cruise control unit connector.
2. If all terminal voltage are OK, replace the cruise control unit.
Terminal Wire color
Connected to Test condition Specification Action
a
(G/Y)
Actuator
M ai n switch off
OV
Main switch on
9V
b (G/B)
Actuator
Main switch off
OV
Go to Step 8
-
Main switch on
9V
c
(GIG)
Actuator
M ai n switch off
OV
M ai n switch on
9V
e
(R)
Main switch
Main switch off
12V
Repair wire (R)
M ai n switch off OV
(Main switch-Cruise control unit)
f
(Y/8) Main switch
Main switch off
OV
Repair wire (Y/8)
Main switch on 12V
(Main switch-Cruise control unit)
T-99