CRUISE CONTROL SYSTEM TESTS - 633CSi (VACUUM SERVO)
A, Vacuum - Check fit and condition of all vacuum and vent lines.
B. Electrical
TEST AT ECU PLUG
COMPONENT/CIRCUIT
RESULT
1. Measure A/C voltage
across terms. 11-12.
Car on hoist in gear
and running.
Signal Generator and
wiring.
10 mph approx. 0.7 V A/C
20 mph approx. 1.4 V A/C
30 mph approx. 2.1 V A/C
40 mph approx. 2.8V A/C
2. Ignition on. Check
voltage at term. 5.
Power supply.
Voltage - 12V. If not,
check wiring.
3. Start car. Jumper
term. 5-3 and then
12-7 momentarily.
Servo.
Servo should activate and
raise engine speed. If
not, check wiring and Servo.
4a. Ignition on (not
running). Check
voltage at term. 6.
b. Ignition off. Check
resistance terminal
6 to ground.
System disconnect
circuit.
Adaptor ground.
No voltage. Push brake pedal
then voltage = 12V, or trans.
to 'N' and voltage = 12V. If
not, check wiring, switches,
and adaptor.
Reading approx 20 to 150 .
Now reverse leads and reading
must remain between 20 and 150
If reading is at oo with either
hook up check adaptor grounding
or replace adaptor.
5. Ignition on. Check
voltage at term. 8.
Control switch OFF.
Move lever to OFF. Voltage
drops from 12 -> 0 volts. If
not, check wiring and switch.
6. Ignition on. Check
voltage at term. 9.
Control switch CONST.
Move lever to CONST. Voltage
jumps 0 to 12 volts. If not,
check wiring and switch.
7. Ignition on. Check
voltage at term. 10.
Control switch RESUME.
Move lever to RESUME. Voltage
jumps 0 to 12 volts. If not,
check wiring and switch.
If these electrical tests are OK, then change the control unit if the system does not
operate correctly.
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