New Holland WorkMaster 50 Service Manual page 941

DTC 426-03-Level 2 Monitoring : Reported Overvoltage of Supply
Control Module : ECU
Context:
The Engine Control Unit (ECU) A-9000 monitors the ECU A-9000 internal 5 V supply. If the 5 V supply exceeds the
maximal limit, this fault will occur.
Cause:
The ECU A-9000 has determined that the 5 V internal voltage supply is too high.
Possible failure modes:
1. Faulty voltage supply.
2. Faulty ECU A-9000, software.
Solution:
1. Verify fault is 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 3.
2. Check the ECU A-9000 supply voltage.
Disconnect the vehicle (VE) harness from the ECU A-9000 at connector X-9102.
To energize the Main relay K-9102, place a jumper wire between the vehicle harness (VE) side of connector X-9102
pin K28 and chassis ground.
Use a multimeter to check for voltage on the vehicle (VE) harness side:
From
X-9102 pin K01
X-9102 pin K03
X-9102 pin K05
A. If the voltage is not present for one or more of the checks, use the appropriate service manual, if necessary,
to repair the faulty conductor.
B. If the voltage is present on all of the checks, check the ECU A-9000 for the appropriate service manual and
re-flash, if necessary.
3. Visually inspect the relevant harnesses and connectors for damage, bent or dislocated pins, corroded terminals,
or broken wires. Verify that the connectors are fully installed. Flex the harnesses involved to reveal intermittent
breaks or shorts in the wiring concerned. Operate the machine while you monitor the display.
A. If you find damage or the display indicates other than normal display readings, then repair the damage discov-
ered during the inspection or locate and repair the other than normal display condition and verify that the error
has been resolved.
B. If you do not find damage and the display indicates only normal readings, then erase the fault code and continue
operation.
Wiring harnesses - Electrical schematic sheet 02 – Engine Control Unit (ECU) power and after treatment
system (engine schematics) (55.100.DP-C.20.E.02)
Electrical systems - FAULT CODES
To
X-9102 pin K02
X-9102 pin K04
X-9102 pin K06
47866583_ 02/12/2015
55.12 [55.DTC] / 220
Value
There should be approximately
12.0 V.
There should be approximately
12.0 V.
There should be approximately
12.0 V.