WABCO 400 500 320 0, Maintenance Manual

Page: 65 / 188

65
Diagnostics
Blink
Code
SPN FMI
Suspect
Component
and Location
ITP
Function
Fault
Description
(FMI)
Cause Repair Information
7 7 4 External
Modulator
Valve
N/A ABS Relay
Valve/
Solenoid
Control -
EV Under-
voltage/
Short Circuit
to Ground
Cable to ABS relay
valve probably has
a short circuit to
ground.
- Verify an external modulator
is installed by checking to see
if a cable is plugged in to the
external modulator port of the
ABS ECU.
- Verify if no cable is attached,
that the external modulator
cap is sealed and there are no
signs of moisture or corrosion
on the pins of the ABS ECU.
- If no external modulator
valve is used and all previous
checks pass, recon
fi gure
the system to a 2S/2M or
4S/2M system depending
on how many sensors are
used through the WABCO
TOOLBOX PLUS™ Software.
- If equipped with an external
modulator verify resistance
from the exhaust and inlet
valve to ground is between 4
to 8 ohms through the whole
circuit.
- Verify there is no continuity
on any of the pins of the
external modulator valve cable
to chassis ground.