DTC B1956

Precautions: Precautions for Headlight Auto Leveling System Service · Precautions for Body, Cab and Accessories · General safety (00)

DTC Detecting Condition and Trouble Area

DTC detecting condition	Trouble area
B1956: Rear Height Sensor Error Any of the following conditions is met. •Rear vehicle height sensor signal circuit voltage is higher than 4.75 V for 10 sec. •Rear vehicle height sensor signal circuit voltage is lower than 0.25 V for 10 sec. •Rear vehicle height sensor power supply voltage is higher than 6.25 V for 10 sec. •Rear vehicle height sensor power supply voltage is lower than 4.45 V for 10 sec.	•Rear vehicle height sensor and/or its circuit •Headlight auto leveling control module

DTC detecting condition

Trouble area

B1956: Rear Height Sensor Error
Any of the following conditions is met.

•Rear vehicle height sensor signal circuit voltage is higher than 4.75 V for 10 sec.
•Rear vehicle height sensor signal circuit voltage is lower than 0.25 V for 10 sec.
•Rear vehicle height sensor power supply voltage is higher than 6.25 V for 10 sec.
•Rear vehicle height sensor power supply voltage is lower than 4.45 V for 10 sec.

•Rear vehicle height sensor and/or its circuit
•Headlight auto leveling control module

Circuit Diagram

[A]:	Headlight auto leveling control module connector (View: [a])	A3:	Rear vehicle height sensor power supply circuit
[B]:	Rear vehicle height sensor connector (View: [b])	1.	Headlight auto leveling control module
A1:	Rear vehicle height sensor ground circuit	2.	Rear vehicle height sensor
A2:	Rear vehicle height sensor signal circuit

DTC Confirmation Procedure

1)Park vehicle on level surface and set ignition “OFF”.

2)Run engine at idle speed for 10 sec. or more.

DTC Troubleshooting

Step	Action	Yes	No
1	DTC check 1)Clear DTC. 2)Set ignition “OFF”. 3)Perform “DTC Confirmation Procedure” and recheck DTC. Is DTC B1956 still detected?	Go to Step 2.	Intermittent trouble.
2	Rear vehicle height sensor circuit check 1)Set ignition “OFF”. 2)Disconnect “E18” and “L37” connectors. 3)Check for proper terminal connections to “E18” and “L37” connectors. 4)If connections are OK, check “A1”, “A2” and “A3” circuits between “E18” connector and “L37” connector for open circuit, short to ground or short to power supply. Is check result OK?	Go to Step 3	Repair or replace defective harness and recheck DTC.
3	Rear vehicle height sensor check 1)Check rear vehicle height sensor. Is check result OK?	Replace headlight auto leveling control module and recheck DTC.	Replace rear vehicle height sensor and recheck DTC.