DTC P0725/86 NE COMMUNICATION LINE SYSTEM

1. Confirm that DTC P0335/12 and 13 [crank angle sensor system] and P0339/13 [crank angle sensor system (intermittent discontinuity)] of the ECD system are put out in addition to DTC P0725/85.

   Standard:

   Inspection result	Step
   Only output of DTC P0725/85	To step A
   Output of DTC P0725/85 and other diagnostic codes	To step B

   

   When a diagnostic code other than DTC P0725/85 is put out, perform trouble-shooting first for that diagnostic code.

   B To the related diagnostic code chart [refer to chapter ES (NO4C)]

   A Proceed to [2]INSPECT TRANSMISSION CONTROL COMPUTER ASSY BY ITSELF (NE)

1. Connect an oscilloscope between connector terminals C7 (NE) and B8 (GND1) of the transmission control computer ASSY. (Refer to page for the terminal layout.)
2. Inspect the waveform between the terminals of the transmission control computer ASSY.

   Standard:

   Item	Contents
   Measuring terminal	NE ↔ GND1
   Instrument setting	2V/DIV, 20ms/DIV
   Measuring condition	Running with vehicle speed of 20 km/h

   
   

   

   The waveform cycle becomes shorter with increasing vehicle speed.

   Inspect and replace the transmission control computer ASSY.

   Proceed to [3]INSPECT WIRE HARNESS AND CONNECTOR (ENGINE CONTROL COMPUTER - TRANSMISSION CONTROL COMPUTER ASSY)

1. Inspect conductivity
   1. Disconnect connector C of the transmission control computer ASSY and the connector D of the engine control computer.
   2. Check the conductivity between the connector on the wire harness side of the transmission control computer ASSY and the connector on the wire harness side of the engine control computer. (Refer to page for the terminal layout.)

      Standard:

      Terminal No. (terminal symbol) (Transmission computer↔meter)	Conductivity
      C7 (NE) ↔ D6 (TAC)	Yes

2. Inspect insulation
   1. Check the insulation between the connector on the wire harness side of the transmission control computer ASSY and body earth. (Refer to page for the terminal layout.)

      Standard:

      Terminal No. (terminal symbol) (Transmission computer)	Conductivity
      C7 (NE) ↔ Body earth	No

   Repair or replace wire harness and connector.

   Inspect and replace the engine control computer.

1. Confirm the DTC P0725/86 is inactive

   • Start the engine and let it idling condition.
   • Verify the DTC P0725/86 is inactive.

   

2. DTC Clear

   • Clear the DTC with Hino DX
   • Confirm the same DTC is not reoccurred

   

P0725/86 is reoccurF Return to first process Other DTC appearF Refer to concerned Trouble shooting

Complete