38C -5V3 MR-413-X44-38C050$010.mif
ANTI-LOCK BRAKING SYSTEM
Fault finding – Introduction
Bosch 8.1 ESP
Vdiag No.: 05
38C
4. FAULT FINDING PROCEDURE (CONTINUED)
4.1 Wiring check
Fault finding problems
Disconnecting the connectors and/or manipulating the wiring may temporarily clear the cause of a fault.
Visual inspection
Look for damage under the bonnet and in the passenger compartment.
Carefully check the protectors, insulation, and routing of the wiring, as well as the mountings.
Physical inspection
When manipulating the wiring, either use the diagnostic tool to detect a change in status, from "stored" to "present",
or the multimeter to view the status changes.
Make sure that the connectors are firmly secured.
Apply light pressure to the connectors.
Twist the wiring harness.
Checking earth insulation
This check is carried out by measuring the voltage (multimeter in voltmeter mode) between the suspect connection
and the 12 V or 5 V. The correct measured value is 0 V.
Checking insulation against + 12 V or + 5 V
This check is carried out by measuring the voltage (multimeter in voltmeter mode) between the suspect connection
and the earth. In the first instance, the earth may be taken on the chassis. The correct measured value should be 0 V
Continuity check
A continuity check is carried out by measuring the resistance (multimeter in ohmmeter mode), with the connectors
disconnected at both ends. The expected result is 1
± 1 for every connection. The line must be fully checked, and the
intermediate connections are only included in the method if this saves time during the fault finding procedure. The
continuity check on the multiplex lines must be carried out on both wires. The measured value should be 1 ± 1.
Checking the supply
This check may be carried out using a test light (21 W or 5 W depending on the maximum authorised load).
