Page 3
TG0040A
Section 2: CAN/J1939 Diagnostics
CAN/J1939 Interface
DESCRIPTION AND OPERATION
The CEN N3218 digital regulator is compatible with
SAE J1939 communications standard for vehicle
networking.
CEN uses MIL-STD connector MS3112E12-10P to
interface between the N3218 and the vehicle J1939
databus and battery box sensors. Mating connector is
MS3116E12-10S or equivalent. If this connection is
not used, it must be sealed with connector cover
MS3181-12CA or equivalent. Connector pinout is
shown in Table 1. Message content is shown in Table 2.
Battery box sensing inputs connect to battery pack
positive terminal (pin J) and battery box thermistor
(pin H). Thermistor is 10K NTC with 32650
Ω
at 0ºC,
10000
Ω
at 25ºC, 3601
Ω
at 50ºC and 1% inter-
changeability. Thermistor location should be chosen
so that it closely represents battery case tempera-
ture. Thermistor connects between pin H and vehicle
chassis, battery pack negative terminal, or negative
bus bar. If either sensing input (pin H or J) is not
used, regulator will default to internal temperature
and alternator voltage.
Pin
Identification
TABLE 1 – J1939 Connector
Circuit Identification
A
B
C
D
E
F
G
H
J
K
J1939+
J1939–
J1939/SHLD
B–/GND
Mfr use only
Mfr use only
Mfr use only
Ext. Temp. Sense
Ext. Voltage Sense
unused
Figure 3 – J1939
Connector Pins
Regulator Readout
Expected Reading
TABLE 2 – N3218 Regulator/J1939 Readout Diagnostics (see Table 3)
Action If Expected Reading Not Present
Alternator Speed
Alternator Voltage
Battery Voltage
Regulator Temp.
Alternator Current
Alternator Load
Battery Temp.
Stator Voltages
1500 to 8000 RPM
26 to 30 V (when charging)
26 to 30 V (when charging)
–40 to 125ºC
0 to 300 A
0 to 100%
–40 to 80ºC
10 to 18 V (when charging)
Check belts and pulley.
Check alternator drive and regulator IGN signal.
Check battery box voltage sense signal.
Check regulator.
Check alternator output cabling.
Check alternator output cabling.
Check battery box thermistor.
Check alternator belts and output.
Notes:
(1) Byte 1 broadcast closest to CAN frame ID.
(2) Contact C. E. Niehoff & Co. for definition of custom proprietary message content.
Table 3 — Message Data
PGN
Name
1
(1)
2
3
4
5
6
7
8
FED5
Alt. Speed
Alt. Speed
FEF7
Alt. Voltage
Alt. Voltage
Batt. Voltage
FEA7
Alt. Temp.
Reg. Temp.
FFC8
Proprietary #1
Alt. Current
(2)
(2)
Alt. Hrs.
Load
Batt. Temp.
FFC9
Proprietary #2
(2)
(2)
OVCO Count
(2)
(2)
(2)
(2)
(2)
FFCA
Proprietary #3 Stator 1 Voltage
Stator 2 Voltage
R
Section 2: CAN/J1939 Diagnostics
Page 3
TG40B
