New Holland WorkMaster 50 Service Manual page 815

DTC 18F-04-Lambda sensor heater power stage short circuit to
ground
Control Module : ECU
NOTE: If the Lambda sensor B-9123 is replaced, it is necessary to perform the Replacement of the Lambda Sensor
- Reset ECU Data with the Electronic Service Tool (EST) before you return the machine to service. See Lambda
sensor - Configure - Reset ECU data (Lambda sensor) (55.989), if necessary.
Context:
The Lambda sensor B-9123 has a heating element encased in ceramic that heats the sensor tip. Whenever the
heater is operating, the heater low side driver power stage contained in the Engine Control Unit (ECU) A-9000 is
monitored for a short circuit to ground condition. If a short to ground condition exists in the heater control circuit, this
fault will occur. For information regarding the functional operation of the Lambda sensor B-9123 see Lambda sensor
- Overview (55.989). For more information regarding the technical specifications of the lambda sensor B-9123, see
Lambda sensor - Technical Data (55.989).
Cause:
The Lambda sensor B-9123 low side driver heater control circuit is shorted to ground.
Possible failure modes:
1. Faulty Lambda sensor B-9123 heater control circuit wiring, short to ground condition.
2. Faulty Lambda sensor B-9123, internal failure.
3. Faulty ECU A-9000, software.
Solution:
1. Verify that the fault present and active.
Use the Electronic Service Tool (EST) to check the status of this fault.
A. If the fault is present and active, continue with Step 2.
B. If the fault is no longer present or in an inactive state, the fault may be intermittent and not currently active.
Continue with Step 4.
2. Check the Lambda sensor B-9123 heater control circuit wiring for a short to ground condition.
Disconnect the vehicle harness (VE) from the Lambda sensor B-9123 at connector X-9123.
Disconnect the vehicle harness (VE) from the ECU A-9000 at connector X-9102.
Use a multimeter to perform the following continuity check on the vehicle harness (VE) side :
From
X-9123 pin 3
X-9102 pin K07
A. If there is continuity, there is a short circuit in the lambda sensor B-9123 vehicle harness (VE) wiring. Use the
appropriate service manual, if necessary, to locate and repair the shorted conductor.
B. If there is no continuity, leave connector X-9123 disconnected and continue to Step 3.
3. Replace the Lambda sensor B-9123.
Use the EST, see Lambda sensor - Configure - Reset ECU data (Lambda sensor) (55.989) if necessary, to
perform the Replacement of the Lambda Sensor - Reset ECU Data.
Use EST to check to see that this fault has been resolved.
A. If the fault has been resolved, return the machine to service.
Electrical systems - FAULT CODES
To
chassis ground
All pins in connector X-9102
47866583_ 02/12/2015
55.12 [55.DTC] / 94
Value
There should be no continuity.
There should be no continuity.