4

GSBC Central ECU

1
2
3
4
5
6
7
8
9

17

3
2
1

10
11
12
13
14
15
16
17
18

X3

1
2
3
4
5

N/C
N/C
N/C
N/C
N/C

X5
X4

X5

X5 CONNECTOR PIN MATCH
PIN

DEVICE

PIN
MATCH

PIN

DEVICE

PIN
MATCH

PIN

DEVICE

PIN
MATCH

1

-

-

7

SAS

1

13

-

-

REFERENCE

DEVICE

PCV

GSBC M-50QR

2

-

-

8

SAS

3

14

-

-

3

-

-

9

SAS

4

15

-

-

4

-

-

10

-

-

16

-

-

5

-

-

11

-

-

17

-

-

6

SAS

2

12

-

-

18

-

-

DEVICE KEY

eTPCM

GSBC eTPCM-90

EPM0-3

GSBC EPM-90

FBM

GSBC FBM-40

SAS

SAS-80

Table 7 – Central ECU X5 Connector Pin Match

SD-27-5023V Rev 000 Bendix® GSBC® System and EBS-90™ (Global Scalable Brake Control System and Electronic Control Unit)

17

GSBC Central ECU

GSBC CENTRAL ECU
Central ECU

Central ECU Mud Cover

Central ECU Full Assembly

Figure 13 – Central ECU Parts and Full Assembly
This section is specifically aimed at providing information
about the Central ECU, as well as diagnosing,
troubleshooting, and addressing potential issues with the
Central ECU.
DESCRIPTION
The Bendix EBS-90 ECU (referred to as Central ECU or
GSBC Central ECU) is a 24V electronic control unit that is
the main controller for the GSBC system. This controller
provides for driver control over the braking characteristics
of air-braked heavy- and medium- duty trucks, tractors,
and buses.
The Central ECU is connected to and controls all other
components that comprise the GSBC system, in addition
to interfacing between the GSBC system and the rest of
the vehicle.
COMPONENT OVERVIEW
The Central ECU is comprised of two (2) main parts.
The first is the ECU and housing, which contains the
ECU circuitry, mounting points, electrical connectors, wire
guides, and housing. The second part is the Central ECU
Mud Cover, which is a plastic shell that snaps on to the
top of the Central ECU. The Mud Cover protects the wiring
harness and electrical connectors that are connected to
the Central ECU from dirt, debris, road spray, and impact.
The Central ECU is only available from the vehicle OEM,
as each ECU is programmed specifically to the VIN of each
vehicle. The Mud Cover is a generic part which is available
without special restrictions.

18

The Central ECU operates at a normal voltage of
approximately 24V-28V. The ECU will not operate below
18.5V or above 32V.
CONDITION

24V OPERATION
Min

Nom

Max

Operation Voltage Range

18.5V

28V

32V

Overvoltage

-

-

>36V

Undervoltage

25%).

AA

Shortcut between sensor wiring connected to
the same EPM (shorted channels) Test pulse
is provided for the WSS, and status of all
other wheel speed signals are monitored.

BB

0x500D95

20493

149

Wheel Speed Sensor 1: Incorrect
Assembly

0x500E31

20494

49

Wheel Speed Sensor 2: No
Signal

Fault is set if WSS changes or drops at
implausible rates (signal is frequently jumping
between 0 and more than 7 mph).

Y

0x500E38

20494

56

Wheel Speed Sensor 2: Signal
Frequency Incorrect

Noisy WSS signal WSS faulty.

Z

0x500E3A

20494

58

Wheel Speed Sensor 2: Signal
Has Too Many Pulses

Noisy WSS signal WSS faulty.

Z

0x500E54

20494

84

Wheel Speed Sensor 2: Missing
Calibration

The deviation between the learned wheel
circumferences and the EOL programmed
values are too large (deviation > 25%).

AA

Shortcut between sensor wiring connected to
the same EPM (shorted channels) Test pulse
is provided for the WSS, and status of all
other wheel speed signals are monitored.

BB

0x500E95

20494

149

Wheel Speed Sensor 2: Incorrect
Assembly

0x500F31

20495

49

Wheel Speed Sensor 3: No
Signal

Fault is set if WSS changes or drops at
implausible rates (signal is frequently jumping
between 0 and more than 7 mph).

Y

0x500F38

20495

56

Wheel Speed Sensor 3: Signal
Frequency Incorrect

Noisy WSS signal WSS faulty.

Z

0x500F3A

20495

58

Wheel Speed Sensor 3: Signal
Has Too Many Pulses

Noisy WSS signal WSS faulty

Z

0x500F54

20495

84

Wheel Speed Sensor 3: Missing
Calibration

The deviation between the learned wheel
circumferences and the EOL programmed
values are too large (deviation > 25%).

AA

Table 18 - GSBC System/ECU Diagnostic Trouble Codes (DTCs)

SD-27-5023V Rev 000 Bendix® GSBC® System and EBS-90™ (Global Scalable Brake Control System and Electronic Control Unit)

29

Troubleshooting

GSBC SYSTEM & ECU DTCS
DTC#

SPN

FMI

DTC NAME

DTC DESCRIPTION

ACTION

Shortcut between sensor wiring connected to
the same EPM (shorted channels) Test pulse
is provided for the WSS, and status of all
other wheel speed signals are monitored.

BB

0x500F95

20495

149

Wheel Speed Sensor 3: Incorrect
Assembly

0x501031

20496

49

Wheel Speed Sensor 4: No
Signal

Fault is set if WSS changes or drops at
implausible rates (signal is frequently jumping
between 0 and more than 7 mph).

Y

0x501038

20496

56

Wheel Speed Sensor 4: Signal
Frequency Incorrect

Noisy WSS signal WSS faulty.

Z

0x50103A

20496

58

Wheel Speed Sensor 4: Signal
Has Too Many Pulses

Noisy WSS signal WSS faulty.

Z

0x501054

20496

84

Wheel Speed Sensor 4: Missing
Calibration

The deviation between the learned wheel
circumferences and the EOL programmed
values are too large (deviation > 25%).

AA

Shortcut between sensor wiring connected to
the same EPM (shorted channels) Test pulse
is provided for the WSS, and status of all
other wheel speed signals are monitored.

BB

0x501095

20496

149

Wheel Speed Sensor 4: Incorrect
Assembly

0x501131

20497

49

Wheel Speed Sensor 5: No
Signal

Fault is set if WSS changes or drops at
implausible rates (signal is frequently jumping
between 0 and more than 7 mph).

Y

0x501138

20497

56

Wheel Speed Sensor 5: Signal
Frequency Incorrect

Noisy WSS signal WSS faulty.

Z

0x50113A

20497

58

Wheel Speed Sensor 5: Signal
Has Too Many Pulses

Noisy WSS signal WSS faulty.

Z

0x501154

20497

84