Honda 2002 Accord Manual page 875

Self-diagnosis
1. The ABS control unit is equipped w i t h a main CPU and a sub CPU, that check each other for problems.
2. The CPUs check the circuit of the system.
3. Self-diagnosis can be classifield into 2 categories:
• Initial diagnosis: Done right after the engine starts and until the ABS indicator goes off.
• Regular diagnosis: Done right after the initial diagnosis until the ignition switch is turned OFF.
4 . W h e n a problem is detected by self-diagnosis, the system:
• Turns the fail-safe relay OFF
• Turns the solenoid valve OFF
• Turn the p u m p motor OFF
• Turns the ABS indicator ON
Self-diagnosis Table
Diagnostic T r o u b l e D e t e c t i o n I t e m Detection Timing
Fail-safe Mode
Code (DTC) Initial
Diagnosis
Regular
Diagnosis
11, 13,15, 17 Wheel sensor (open/short t o b o d y g r o u n d / s h o r t t o p o w e r )
. »
A
12, 14, 16, 18 Wheel sensor {electrical noise/intermittent interruption)
S, A and L, S and L
21-24 Pulser
A and L
31-38 Solenoid (short to body ground/short to wire)
S
41-44
Wheel lock
O
A and L
51 Motor lock
c.
S and L
52
Motor stuck OFF
O
A and L
53 M o t o r stuck O N
G
C'I A and L
54
Fail-safe relay
C
S
61
Low ignition voltage
o
B
62 High ignition voltage B
71 Different diameter tire
o
S
81
• " " •
Central Processing Unit (CPU) diagnosis, and ROM/RAM diagnosis
o o
S
Operation M o d e Table
Operation Mode Description
A B S Indicator
Regular operation
Operation in n o r m a l c o n d i t i o n OFF
Fail-safe m o d e - S
The ABS control unit t u r n s t h e s y s t e m off w h e n t h e c o n t r o l unit detects a p r o b l e m . Comes O N w h e n a p r o b l e m is
detected.
Fail-safe m o d e - A If the A B S control unit detects a m a l f u n c t i o n d u r i n g an e m e r g e n c y s t o p , it w i l l t u r n off the
m a l f u n c t i o n i n g c o m p o n e n t , a n d c o n t i n u e t o m o d u l a t e t h e rest of t h e A B S system until t h e
vehicle comes t o a stop. A t that, the entire system w i l l be t u r n e d off until the p r o b l e m goes
away.
Comes O N w h e n a p r o b l e m is
detected.
Fail-safe mode-L The ABS c o n t r o l unit stores a DTC in back-up m e m o r y w h e n it detects a p r o b l e m . If a
p r o b l e m is detected w h e n the i g n i t i o n s w i t c h is t u r n e d O N (II), t h e A B S control unit w i l l t u r n
the system off. If the p r o b l e m g o e s a w a y , the ABS c o n t r o l unit w i l l t u r n the system on again.
O N
Fail-safe m o d e - B The ABS control unit w i l l t u r n t h e s y s t e m off if i g n i t i o n v o l t a g e d r o p s , and w i l l t u r n on again
w h e n ignition voltage returns t o n o r m a l .
Comes O N w h e n a p r o b l e m is
detected.
On-board Diagnosis Function
The ABS control unit is connected to the 16P Data Link Connector.
The ABS can be diagnosed w i t h the Honda PGM Tester.
The ALB Checker cannot be used with this system. For air bleeding, and checking wheel sensor signals, use the Honda
PGM Tester. See the Honda PGM Tester user's manuals for specific operating instructions.
(cont'd)
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