How to Solve Allison 3000 & 4000 Gen5 Engine Trouble Code P0703

This instruction show you guide on how to solve Allison 3000 & 4000 Gen5 engine fault code P0703 break switch circuit.

 

 

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DIAGNOSTIC RESPONSE:

No Neutral to Drive shifts for refuse packer. TCM inhibits retarder operation if a TPS code is also active.

 

CIRCUIT DESCRIPTION:

This test monitors whether vehicle service brake switch status is in a stuck “ON” or “OFF” state.

ACTION TAKEN WHEN THE DTC SETS:

1 The TCM does not illuminate the CHECK TRANS light.

2 DTC is stored in TCM history.

3 Some feature ranges may be inhibited when a valid Service Brake Status(SBS) state is not detected by the TCM. The range inhibit light will illuminate when range is inhibited.

 

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:

Use the diagnostic tool to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.

 

DIAGNOSTIC AIDS:

1 Open or short in wire 103 or wire 162.

2 Malfunctioning brake system control components such as:

– Miswired or defective brake system wiring.

This DTC may be caused by:

– Defective brake pressure switches.

3 Defective TCM.

More Allison repair case,please refer to Allison Trouble Repair