Trailer Guide Schematics Software

EB+ ISO 7638 socket to plug

Find here extended description, connector views, and help for diagnostic as well !

Description

  • 24V key slot
  • Conforms to IP67 when mated with ISO7638 connections
  • Cable insulation material : PVC

ISO7638 socket - ISO7638 plug

ISO7638 Socket and plug 7 pin.png

Pin Description Color Section (mm2)
1 B+ Permanent Red 4
2 B+ Ignition Black 1.5
3 B- Ignition Yellow 1.5
4 B- Permanent Brown 4
5 Lamp return White 1.5
6 CAN High White-green 1.5
7 CAN Low White-brown 1.5

Diagnostic

ISO7638 connection is the mandatory power supply for ABS/EBS systems. If the system is showing a wrong function, the power supply must be the first step of the diagnostic!

Before to use the table below, first check the reaction of the system at power ON, either with service brake applied (Brake pedal) or with the red coupling head disconnected (Emergency braking mode) or with the yellow line supplied (At 6.5 bar air pressure).

When switching power ON

  • Each modulator exhausts one time (the number of exhausts must be the same as the number of modulators).
  • ABS warning lamp on dashboard indicates a specific sequence (ON/OFF) or (ON/OFF/ON)

If not, check power supply :

Test points

(with 21W lamp)

 Condition Required value Measured value Comments

Power-A plug

1 - 4

ISO7638 connected

Switch power OFF

 B+  

If permanent power is missing (0V), solenoids are not powered.

If measured value is below B+ (voltage drop), it can indicate a resistance in the wiring.

Next steps :

  • check for oxidation marks in the connectors
  • check truck power supply
  • check the continuity of the wires with ohmmeter between ISO7638 socket/plug and ECU plug. (R<5Ω for correct operation)

Power-A plug

2 - 3

ISO7638 connected

Switch power OFF

0V

  

A permanent power indicates a wrong wiring or short circuit.

Next steps :

  • check for oxidation marks in the connectors
  • check truck power supply
  • check the wire position in ISO7638 socket/plug
  • check isolation between wires with ohmmeter

 

Power-A plug

2 - 3

ISO7638 connected

Switch power ON

B+

  

If switch power is missing, ECU is not powered.

If measured value is below B+ (voltage drop), it can indicate a resistance in the wiring.

Next steps :

  • check for oxidation mark in the connectors
  • check truck power supply
  • check the continuity of the wires with ohmmeter between ISO7638 socket/plug and ECU plug. (R<5Ω for correct operation)

Diagnostic

ISO11992 - EBS only

The ISO11992 is a mandatory connection between trucks and trailers. Several messages are sended from both side to the other.

This communication is also used for diagnostic purpose. In the ISO7638 connection, Pin 6 and 7 are used for this communication bus (CAN High and CAN Low).

Test points Condition Required value Mesured value Comments
6 - 4 Power ON

CAN High is around 2/3 of B+

Usually between 12V and 18V

  

The required value depend of the load on the CAN bus (amount of message, internal resistance of ECU)

Next step :

  • check for oxidation marks in the connectors
  • check the continuity of the wires with ohmmeter (R<5Ω for correct operation)
7 - 4 Power ON

CAN low is around 1/3 of B+

Usually between 6V and 10V

  

The required value depend of the load on the CAN bus (amount of message, internal resistance of ECU)

Next step :

  • check for oxidation marks in the connectors
  • check the continuity of the wires with ohmmeter (R<5Ω for correct operation)
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