BMW 7 SERIES 1988 E32 Cruise Control Acutator

BMW Cruise Control Actuator
1985 to 1996
Technical Data
November 26, 2005

Table of Contents
Usage Cross Reference ................................................................ 3
Theory of Operation .................................................................... 5
Actuator Failure Modes ................................................................. 6
External Description .................................................................... 7
Internal Description ..................................................................... 9
Throttle Cable Removal .............................................................. 10
Disassembly ............................................................................. 13
Actuator Removal ...................................................................... 21
Circuit Board Pictorial ................................................................. 24
Circuit Board Schematic ............................................................. 25
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BMW Cruise Control Actuator 1985 to 1996 – Technical Data page 2 of 25
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Usage Cross Reference
This actuator was used on several BMW models from October 1985
through May 1999. The chart below may be used to cross reference
the usage of the actuator.
Part #: 65711378315
Chassis Model Body Engine Zone Manufactured
from to
E31 840i Coupe M60 America Sep-93 Nov-95
E31 840Ci Coupe M62 America May-95 Jul-97
E31 840i Coupe M60 Europe Dec-92 Feb-96
E31 840Ci Coupe M62 Europe Dec-94 May-99
E32 735i Sedan M30 America Aug-86 Jun-92
E32 735iL Sedan M30 America Jan-88 Jul-92
E32 740i Sedan M60 America Jun-92 Apr-94
E32 740iL Sedan M60 America Jun-92 Mar-94
E32 735i Sedan M30 Europe Oct-85 Jul-92
E32 730i Sedan M30 Europe Jul-86 Mar-94
E32 750iL Sedan M70 Europe Nov-86 Mar-94
E32 735iL Sedan M30 Europe Jun-87 Jul-92
E32 750i Sedan M70 Europe Jul-87 Mar-94
E32 730iL Sedan M30 Europe Dec-87 Mar-94
E32 750iLS Sedan M70 Europe Sep-88 Mar-94
E32 730i Sedan M60 Europe Mar-91 Mar-94
E32 740i Sedan M60 Europe Sep-91 Mar-94
E32 740iL Sedan M60 Europe Oct-91 Mar-94
E32 730iL Sedan M60 Europe Jun-92 Mar-94
E34 525i Sedan M20 America Jan-88 Aug-90
E34 535i Sedan M30 America Jan-88 Feb-93
E34 M5 3.6 Sedan S38 America Sep-89 Mar-93
E34 525i Sedan M50 America Jun-90 Dec-95
E34 525i Touring M50 America Oct-91 Jan-96
E34 530i Sedan M60 America Nov-92 Dec-95
E34 530i Touring M60 America Nov-92 Nov-95
E34 540i Sedan M60 America Nov-92 Dec-95
E34 535i Sedan M30 Europe Mar-87 Apr-93
E34 520i Sedan M20 Europe Jun-87 Sep-90
E34 525i Sedan M20 Europe Jun-87 Aug-90
E34 530i Sedan M30 Europe Jun-87 Jul-90
E34 M5 3.6 Sedan S38 Europe Apr-88 Apr-92
E34 525i Sedan M50 Europe Jan-89 Dec-95
E34 520i Sedan M50 Europe Mar-89 Dec-95
E34 518i Sedan M43 Europe Mar-90 Dec-95
BMW Cruise Control Actuator 1985 to 1996 – Technical Data page 3 of 25
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Usage Cross Reference
E34 520i Touring M50 Europe Nov-90 Jun-96
E34 525i Touring M50 Europe Dec-90 Jun-96
E34 525ix Sedan M50 Europe Apr-91 Dec-95
E34 525ix Touring M50 Europe Jul-91 Mar-96
E34 M5 3.8 Sedan S38 Europe Jul-91 Jul-95
E34 530i Sedan M60 Europe Mar-92 Dec-95
E34 540i Sedan M60 Europe Mar-92 Dec-95
E34 M5 Touring S38 Europe Mar-92 Jul-95
E34 530i Touring M60 Europe May-92 Jun-96
E34 540i Touring M60 Europe May-93 Jun-96
E34 518i Touring M43 Europe Nov-93 Jun-96
E34 518g Touring M43 Europe May-95 Jun-96
E36 325i Sedan M50 America Oct-90 Sep-94
E36 325is Coupe M50 America Nov-90 Sep-94
E36 318i Sedan M42 America Nov-91 Sep-94
E36 318is Coupe M42 America Nov-91 Sep-94
E36 320i Sedan M50 America Sep-92 Sep-94
E36 325i Convertible M50 America Nov-92 Sep-94
E36 318i Convertible M42 America Oct-93 Sep-94
E36 M3 Coupe S50 America Nov-93 Sep-94
E36 325i Sedan M50 Europe Nov-89 Sep-94
E36 320i Sedan M50 Europe Jan-90 Sep-94
E36 325i Coupe M50 Europe Oct-90 Sep-94
E36 320i Coupe M50 Europe Feb-91 Sep-94
E36 M3 Coupe S50 Europe Mar-92 Sep-94
E36 325i Convertible M50 Europe Aug-92 Sep-94
E36 320i Convertible M50 Europe Nov-92 Sep-94
E36 316i Sedan M43 Europe Feb-93 Sep-94
E36 318i Sedan M43 Europe Feb-93 Sep-94
E36 316i Coupe M43 Europe Mar-93 Sep-94
E36 318is Sedan M42 Europe May-93 Sep-94
E36 316i 1.6 Compact M43 Europe Jun-93 Sep-94
E36 318i Convertible M43 Europe Nov-93 Sep-94
E36 M3 Convertible S50 Europe Nov-93 Sep-94
E36 318ti Compact M42 Europe Mar-94 Sep-94
BMW Cruise Control Actuator 1985 to 1996 – Technical Data page 4 of 25
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Theory of Operation
The throttle is simultaneously linked by cable to the cruise control
actuator and by a second cable to the accelerator pedal. The core of
the cruise control actuator is a small motorized drum which winds or
unwinds a belt of rubberized fabric. This control belt is affixed to the
cable connected to the throttle. Thus, by winding the belt the throttle
cable can be retracted, or by unwinding it can be extended.
When the cruise control is not in use, the motor drive is disengaged
from the drum. This allows the drum to turn easily and the throttle
cable to move freely in response to accelerator pedal action. A
clockwork style spring supplies mild tension to keep the belt wrapped
around the drum and also takes up slack from the throttle cable.
A solenoid is used to engage the motor drive with the drum. When the
solenoid is energized a small armature is moved which pushes a
sprocket into contact with the integrated gear on the drum. At this
point, if current is supplied to the drive motor, the drum will wind. If
the polarity of the current is reversed, the drum will unwind.
The control unit (“brain”) is located in the electronics bay. The control
unit can thus command the actuator to engage or disengage, to reel in
the throttle cable or extend it. This provides the necessary control
capabilities.
To maintain a set vehicle speed, the control unit needs to know the
rotational position of the drum. A potentiometer (variable resistor)
integrated into the drum supplies this information to the control unit.
A resistance proportional to the position of the drum is constantly
presented to the control unit. This feedback allows the control unit to
determine how the actuator has responded to its commands.
By using the current vehicle speed (supplied by another sensor) along
with the feedback from the actuator, the control unit can adjust the
actuator as necessary to maintain vehicle speed.
BMW Cruise Control Actuator 1985 to 1996 – Technical Data page 5 of 25
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Actuator Failure Modes
The cruise control actuator will seem to work only intermittently or
partially when a tooth is broken in the gear driving the control belt
drum. This is because the control unit will attempt to operate the
actuator, but gets inconsistent feedback from the potentiometer when
the drive encounters the broken tooth.
Figure 1 - Control belt drum with broken tooth
When the inconsistent feedback is received the control unit will
eventually give up and disengage. A similar effect is noticed when the
potentiometer resistance surface or wipers become pitted or burned.
When the control belt breaks or the motor or solenoid burns out a
complete failure of the actuator is observed.
BMW Cruise Control Actuator 1985 to 1996 – Technical Data page 6 of 25
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External Description
The cruise control actuator is enclosed in a two part plastic housing.
The throttle control cable protrudes through a fixture on the top half.
A round male electrical connector for the control cable is also located
on the top half.
Figure 2 - Actuator top view
Figure 3 - Actuator side view
BMW Cruise Control Actuator 1985 to 1996 – Technical Data page 7 of 25
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External Description
Figure 4 - Actuator side view
Figure 5 - Actuator bottom view (mounting plate and cable removed)
BMW Cruise Control Actuator 1985 to 1996 – Technical Data page 8 of 25
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Internal Description
When the actuator is disassembled, the following components are
revealed.
Figure 6 - Internal components
Figure 7 - Internal components (alt. view)
BMW Cruise Control Actuator 1985 to 1996 – Technical Data page 9 of 25
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Internal Description
Throttle Cable Removal
The throttle cable may be separated from the cruise control actuator.
This may be accomplished while the cruise control actuator is in the
automobile.
Figure 8 - Throttle cable release tab
Figure 9 - Depress tab and pull cable
BMW Cruise Control Actuator 1985 to 1996 – Technical Data page 10 of 25
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