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Copyright 2017 Cummins Inc.
TABLE 4-30B. TROUBLESHOOTING ANALOG SIGNALS BETWEEN ANALOG AND
DIGITAL BOARDS
WARNING
Many troubleshooting procedures present hazards that can result in severe personal inju-
ry or death. Only qualified service personnel with knowledge of fuels, electricity, and machinery haz-
ards should perform service procedures. Review Important Safety Instructions page.
NOTE: Perform this procedure after you have isolated the problem to either the analog
board (A33) or to the digital board (A32). You must have schematics and wiring
diagrams to identify the various inputs and outputs.
2b. This step is for multiplexed signals. Is more than one multiplexed signal reading bad?
No. If the input to the analog board is correct and only one multiplexed signal is reading bad, replace
the analog board.
Yes. If more than one multiplexed signal reading is bad, remove the ribbon cable connector at
A32 J3 and check the front panel digital display of the bad inputs. It should read 0 for all inputs ex-
cept the temperature inputs (which should read less than 32 F or less than 0 C) and power factor
(which should read “NA”).
If any values read incorrectly, replace the digital board.
If they all read correctly, measure voltages on the multiplexer control lines (with A32-J3 discon-
nected, measure from Digital board connector J3). Voltages should be:
A32-J3-23: 3.0 0.25 VDC
A32-J3-24: 2.4 0.25 VDC
A32-J3-27: 1.4 0.25 VDC
A32-J3-33: 3.0 0.25 VDC
A32-J3-34: 3.0 0.25 VDC
If these control (select) line voltages are not correct, replace the digital board.
If these control (select) line voltages are correct (and the input to the analog board is correct),
reconnect the ribbon cable connector (through harness tool) at A32 J3 and check the 5 VDC
reference at A32 J3-12 and the 12 VDC supply at A32 J3-20.
If the 5 VDC and the 12 VDC voltages are OK, replace the analog board.
If the 5 VDC and the 12 VDC voltages are not OK, disconnect A32 J3 and check the
voltages again (measured from Digital board side).
If the 5 VDC and the 12 VDC voltages are OK with A32 J3 disconnected, replace the
analog board.
If the 5 VDC and the 12 VDC voltages are not OK with A32 J3 disconnected, replace
the digital board.
*CAUTION: Wearing a wrist strap, set S12 to Off and A32 S5 to Standby before connecting/disconnecting harness plugs.
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