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TM-9-2320-334-13&P LHST Operator, Field and Parts Manual M1147A1 Trailer Download

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TM 9-2330-334-13&P THEORY OF OPERATION – Continued 0003 00 Change 1 0003 00-8 ABS ECU The ABS ECU is mounted towards the rear of the trailer right behind the rear air tank. The ABS ECU monitors and regulates release of air to the service brake air chambers using two relay valves that are triggered when speed sensors (one on each wheel) detect trailer wheel lock-up. The relay valves modulate the air supply by sending pulses of air. In between air pulses, the service brakes release, thereby preventing wheel lock-up. ABS ECU Valve Assembly The ABS ECU valve assembly contains the two relay valves.