Isuzu 2000 Trooper Workshop Manual page 417

Check flow Trouble code
6
If the reference wire (15) is short-circuited to GND, the
speed signal is not generated. If the wire is short-circuited
to the battery voltage, the signal level becomes faulty.
Phenomenon
13 The reference is short-circuited to
15 The reference Vb is short-circuited.
DRIVE LINE CONTROL SYSTEM (TOD)
GND.
4B2–39
Standard
Reference ] 5 V
D04RY00004