ehc BMW X5 2001 E53 Workshop Manual

TABLE OF CONTENTS
Subject Page
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Hood/Front Grille . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Doors/Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Interior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Climate Control Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Cargo Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Tailgate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Drivetrain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Front Suspension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Rear Suspension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
EHC Control System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Steering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
Wheels & Tires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
Fuel Supply System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
Exhaust System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
Power Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
Component Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
STO36 X5

24
Cargo Area
The full size spare tire is mounted
below the load floor with the LVA air
supply system for the air springs
located beneath the spare.
The battery is mounted below the LVA
in a molded plastic battery box, along
with the EHC control module and the
PDC control module. If the optional
trailer towing package is installed, the
trailer module is also installed in the
module carrier.
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Rear Suspension
The rear suspension is the “intragal” multi-link design taken from the E38/E39 vehicles.
Several components AER made from aluminum to erduce the unsprung weight. The X5
with the M62TU engine uses the EHC (air spring) suspension system. The EHC functions
the same as the E39 Sport Wagon with only minor differences to the components and lay-
out of the system. The X5 with the M54 engine will use standard springs in the rear with the
EHC system as an option. The rear struts on the X5 are mounted to the body instead of
the sub-frame.
The rear axle sub-frame is mounted to the body through four bushings (larger than E38) for
increased load and comfort. The rear differential is mounted through three rubber bushings
two in the front and one hydromount in the rear. The wheel bearings are similar to the E39
but incorporate different seals - designed for off-road use.
New special tools are available for adjusting the rear suspension due to the limited space.
Rear Axle Technical Data
Track: 1576mm
Toe In: 18 Feet
Camber 1 Degree 50 Feet

35
Overview of EHC Control System
The control philosophy of EHC is to "Initiate a control sequence only when necessary". The
system offers the following advantages:
• The control system operates independently from the vehicle’s engine (no engine driven
hydraulic pump system as per previous self leveling systems).
• Individual control of the rear wheels is possible
• An uneven load is identified and compensated for
• Uneven road surfaces are identified and not compensated for
• Automatic control is interrupted when cornering
• The system is diagnosable using the DIS or MoDiC
The air suspension system consists of the following components:
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EHC System Components
Control Module
The Control Module is mounted in the module carrier box in the luggage compartment on
the right side. It contains the processing electronics and final stages for operation of the
EHC system.
The control module receives the follow-
ing inputs for its processing functions:
• KL 30 & 31 (Power/Ground)
• KL 15
• Left & Right Ride Height Sensors
• K Bus for;
- Vehicle speed
- Engine running
- Door/tailgate - open/closed
The control module incorporates two filters (slow/rapid) for processing the input signals
from the ride height sensors. Depending on the operating mode, either the slow or rapid fil-
ter is used to check the need for a regulating sequence.
The slow filter is used during the normal operation mode to prevent normal suspension trav-
el from causing the system to make adjustments.
The rapid filter is used during the pre-run and tailgate (LID) modes to ensure that the sus-
pension is adjusted quickly while the vehicle is being loaded or checked prior to operation.
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EHC System Operation
A fully functional EHC system is controlled by one of three different modes of operation.
The operation mode is selected by the control module based on current conditions provid-
ed by the monitored input signals. The main modes of operation are:
• Pre-Run/Post-Run Mode
 Normal Mode
 Tailgate Mode
Two special operating modes are also included in the control module programming.
 New/replacement mode(pre ZCS encoded). This mode provides basic operation.
 Transport Mode - Transport mode is set at the factory and raises the vehicle 30mm to
prevent vehicle damage during transportation. It must be deactivated with the DIS/
MoDiC prior to customer delivery.
Pre-Run/Post-Run Mode
The Pre-Run mode is activated when the vehicle is parked and the control module is in the
sleep mode. Opening a door or the tailgate initiates a system wake up and the control mod-
ule comes on-line.
The control module performs a self-check of the control electronics and sensors. If no fault
is found, the system will check the ride height and institute a rapid regulation if the height
varies by more than 40mm.

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EHC Service Information
Diagnosis / Coding
• The EHC control module is connected to the diagnostic link. The EHC control module
activates the fault display in the instrument cluster to alert the operator of the off-line sta-
tus of the system. The EHC control module stores up to three electrical/electronic
faults.
• Diagnosis/troubleshooting of EHC is carried out using the fault symptom troubleshoot-
ing program of the MoDiC or DIS. The EHC system has an extensive diagnosis program.
• Replacement control modules are shipped in the factory mode. The control modules
must be ZCS encoded using the DIS or MoDiC to activate the operating parameters.

51
Power Distribution
The maintenance free 90 AH battery
in the X5 is mounted in the rear below
the spare tire and EHC compressor
unit. The battery box is formed of
molded plastic and the positioning of
the battery aids in weight distribution.
As with all BMW vehicles, the battery
is equipped with the BST on the pos-
itive battery cable.
Power distribution for the vehicle and
systems is through two fuse carriers
mounted in the right storage com-
partment in the rear and above the
glove box in the front.
The battery jump/charge point is
located in the engine compartment on
the left side of the fire wall.
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