Automatic Lift Axle Troubleshooting - WABCO iABS 2S/1M Standard Maintenance Manual

Troubleshooting
9 Troubleshooting
Hazard Alert Messages
Read and observe all Warning and Caution hazard alert messages in this publication. They provide
information that can help prevent serious personal injury, damage to components, or both.
DANGER
Release all pressure from the air system before you disconnect any components. Pressurized air can
cause serious personal injury.
WARNING
To prevent serious eye injury, always wear safe eye protection when you perform vehicle maintenance or
service.
WARNING
Park the vehicle on a level surface. Block the wheels to prevent the vehicle from moving. Support the
vehicle with safety stands. Do not work under a vehicle supported only by jacks. Jacks can slip and fall
over. Serious personal injury and damage to components can result.
WARNING
Ensure the trailer has correct electrical grounding; refer to SAE Specifi cation J1908.
WARNING
When you work on an electrical system, the possibility of electrical shock exists, and sparks can ignite
fl ammable substances. You must always disconnect the battery ground cable before you work on an
electrical system to prevent serious personal injury and damage to components.
WARNING
It is also recommended to disable or lower any lift axle or tag axle system on the trailer before working
on it. Otherwise, the user has to be aware of possible sudden motion of trailer vehicle body that can lead
to injuries.

9.1 Automatic Lift Axle Troubleshooting

ECUs 400 500 350 and 400 500 430 0 (Premium iABS units) are the only trailer ABS ECU/valve
assemblies that have the capability of the automatic lift axle feature being able to be activated and turned
on.
The fi rst step that should be taken when troubleshooting the Automatic Lift Axle system is to ensure that the
system is pneumatically plumbed correct and electric connections are also correct. Refer to Figures 9.9,
9.10, and 9.11 in this section for the correct schematic, depending upon the override switch confi guration.
For additional information, refer to TP19039, Automatic Lift Axle Installation Manual, available at
www.wabco-na.com.
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