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WABCO Ignition Power Blink Code Diagnostics

This page shows how to initiate the active fault blink code display on WABCO TCS2 ABS trailer valves. It is generally applicable to trailers sold in the US market after March 2001.

It is assumed the constant power to the ABS is provided by the auxiliary (blue) wire in the harness. This circuit must be powered on and off in proper sequence.. This can be done by turning the key switch on a properly wired tractor connected to the trailer or switching the auxliary (blue) circuit using a light tester or other suitable means.

Battery chargers and many other AC converters can cause the ABS to react erratically. A 12 volt battery is the recommended source for a tester.

Initiate Blink Code Display On Trailer Warning Lamp
1. Turn on power to the blue wire for no more than five seconds.
2. Turn off the power off for a moment.
3. Turn the power back on
4. If light goes off after a few seconds there is no active fault. Otherwise continue to step 5.
5. After a short delay the warn lamp will flash several quick times followed by a longer pause.
6. Count the quick flashes to get the fault blink code. This will be repeated three times
7. See the chart below for more information about specific codes

Light Blink Code Cause Location Checks
3 Sensor BU1 Sensor or sensor cable. Follow cable from port labeled with port number (YE1, BU1, ...) to wheel end. Check cabling for short or no circuit, hub for excessive runout, exciter ring for damage, and sensor gap. Starter Control
4 Sensor YE1
5 Sensor BU2
6 Sensor YE2
7 External Modulator External modulator and/or cable Check the cable for connection and continuity. Verify valve function.
9 Internal Modulator Internal Inlet Control #2 Verify proper installation. If code continues, contact Meritor WABCO for assistance.
10 Internal Inlet Control #1
11 Internal Outlet Control
14 Power Supply Power cabling and connectors Verify proper electrical installation. Check power supply.
15 ECU Failure ECU Internal Failure Verify proper installation. If code continues, contact Meritor WABCO for assistance.
16 SAE J1708 Failure Contact Meritor WABCO for assistance.
17 SAE J2497 Failure
18 Generic IO Failure Cabling Verify proper electrical installation. Check power supply.


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