Spicer CTIS (Central Tire Inflation System) Troubleshooting Guide - Manual (Page 54)

51
Service Codes
Solid Warning Lamp or Solid OVER SPEED (Codes 18, 76, 77)
Type: Speed Signal
Code Description
A “Speed Signal” code indicates a faulty speed sensor signal.
In general, the system is configured to accept speed signals
from any one of several sources (analog, digital, J1708/1587
or J1939). In this standard configuration, a loss of speed sig-
nal fault is indicated by code 18. In some specific instances, a
vehicle may be configured to only accept speed from a spe-
cific data link. In these cases, codes 76 (SAE J1708/1587) and
code 77 (SAE J1939) may be used to indicate a speed signal
fault.
• A wiring or sensor connection.
• A misadjusted or faulty sensor.
• A missing data link speed signal. (J1708/1587 or
J1939)
Note: These codes will occur if Electronic Control Unit (ECU)
power has been cycled 50 times and no speed signal is
received. Fifty power cycles can occur after 25 engine
starts without moving the vehicle, however the code
will clear as soon as a speed signal is received.
See “Troubleshooting Tips” for general guidelines on system
diagnostics.
System Mode Condition Possible Causes (listed in order of likely occurrence)
Normal Operation No speed signal • ECU power cycled 50 times without vehicle being moved.
• Sensor disconnected or loose plug.
• Either speed sensor wire is open (broken wire).
• Either speed sensor wire is shorted to ground (bare wire is touching the frame).
• Faulty speed sensor.
• Sensor actuation failure.
• Tang drive broken/disconnected on mechanical sensor.
• Gap not adjusted correctly on pole sensor.
• Sensor wires shorted together.
• Expected data link message not received
A B
Speed Sensor
Harness Connector
T S
A B
C
U
R
P
a
b
c
V
D
E
F
G
W
H
X
J
K
Y L
M Z
N
ECU Harness Connector
A B C D E
A B C D E
A B C D E
F G H J K 3
2
1
F G H J K
F G H J K
– or –