Meritor TACTX HMIS Maintenance Manual page 34

Diagnostics
J1939 SPN
SPN
Description
Air Suspension
1090
Supply Pressure
Auxiliary
1387
Pressure #1
844 Pneumatic
Control Unit
(PCU)
Page 32
Table 8: Pneumatic Control Unit Faults
J1939 FMI
FMI Symptom
Description
No real time
info
Data Valid But
on tank
Above Normal
0 pressure.
Range - Most
Using
Severe Level
secondary
sensor
No SHC
Data Valid But
activity,
Below Normal
1 but CAN
Range - Most
messages
Severe Level
exist
Incorrect
supply
pressure. If
Data Erratic,
read too low,
2 Intermittent or
no raising, if
Incorrect
read too high,
possible
lowering.
Bad Intelligent
12 Device or
Component
Data Valid But
Above Normal
0
Range - Most
Severe Level
Data Valid But
Below Normal
1
No real time
Range - Most
info on air
Severe Level
spring
Data Erratic,
pressure.
2 Intermittent or
Incorrect
Bad Intelligent
12 Device or
Component
Vehicle not
Out of level at any
13
Calibration height
setting.
Meritor Maintenance Manual MM-0997 (Revised 12-09)
Cause Component
Tank pressure Tank pressure
sensor failed sensor
high or low. malfunction.
Low tank
pressure.
No supply air
due to
Compressor, air
vehicle not
tank, air lines.
running,
plumbing or
compressor
failure.
Lack of tank
pressure,
Tank pressure possible
sensor wrong. pressure
sensor
malfunction.
Loss of
communication
F
with tank
pressure sensor
Manifold
Manifold
pressure
pressure sensor
sensor failed
malfunction.
high or low.
Manifold Manifold
pressure pressure
sensor failed damaged or not
high or low. connected.
Manifold Manifold
pressure pressure sensor
sensor wrong. damaged.
Manifold Loss of
pressure communication
sensor failed with manifold
high or low. pressure sensor
Production Production
height height
calibration calibration
process failed. process failed.
Section 4
Action
Replace PCU.
Verify supply
pressure is
present.
Check air
compressor
and reservoir.
Use check
valve from
tank to P1
supply.
Replace PCU.
Replace PCU.
Replace PCU.
Replace PCU.
Recalibrate
height
sensors.