differential BMW 7 SERIES 1981 E23 Cruise Control

CRUISE CONTROL SYSTEM TESTS

(ELECTRIC ACTUATOR)

Use BMW Service Test 2013 to check function of system

as follows:

Program: Enter M (Multimeter)

Enter 13 (Frequency out)

Enter 110 (Hz)

Press

Enter 02 (U. AC.)

Press

1. Detach the differential reed switch plug and attach frequency

out (+) to brown/red wire and frequency out (-) to brown

wire.

2. Turn on ignition.

3. Speedometer should show approximately 50 mph.

4. Engage cruise control and monitor the actuator. (It should

pull the throttle open.)

5. If cruise control does not engage, check for A.C. voltage on

E.C.U. plug terminal #6. (It should be approximately 4.0

volts.)

6. Check plug connections on back of instrument cluster.

7. If system is still inactive, perform the following tests:

Test at ECU Plug
Component/Circuit

Result

1. Ignition on—check volt-

age at Terminal #1.
Power supply

12 Volts. If not, check

wiring and fuse.

2. Ignition on—check volt-

age at Terminal #2.
Control switch OFF

Move lever to OFF. Voltage

drops from 12V to 0V. If

not, check wiring and

switch.

3. Ignition on—check volt-

age at Terminal #4.
Control switch CONST.

Move lever to CONST.

Voltage jumps 0 to 12V.

If not, check wiring and

switch.

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