Honda Civic Service Manual page 921

Troubleshooting Flowchart - Vehicle Speed Sensor
(VSS)
NOTE: Record all freeze data before you troubleshoot'
Po$rible Ctuse
. D i s c o n n e c t e d v e h i c l e s p e e d
sensor (VSS) connectol
. Short or open in VSS wire
' Faulty VSS
@
. Make sure lifts, iacks, and sal€tY stands are placed properly lsoe section 1)'
. Set the parking brake securelv, and block the rear wheels'
. iacr upile rront or the vehicle, and support it with safety st'nds'
TCM CONNECTORS
Wire side of female terminals
. OBD ll Scan Tool indicates Code
P1791.
. Setf-diagno3is E indicato. light
blinks tour times.
Refer to seclion 23 for vehicle
soeed sensor IVSSI test
Check the VSS Voltage:
1 . R a i s e t h e v e h i c l e
2 . S h i f t t h e t r a n s m i s s i o n t o l E
p o s r t l o n .
3 . D i s c o n n e c t t h e A ( 2 6 P ) a n d B
( 2 2 P ) c o n n e c t o r s f r o m t h e
T C M .
4 . T u r n t h e i g n i t i o n s w i t c h O N { l l ) .
5 . R o t a t e t h e f r o n t w h e e l a n d
check for the voltage between
t h e 8 5 a n d 4 1 3 o r A 2 6 t e r m i -
n a l s . B l o c k t h e o t h e r w h e e l s o
at does not turn
Check for oP€n in the wire
between the 85 terminal and the
vehicle speed sensor {VSS}. lf
wire is OK, check the vSS (see
soction 23).
D o e s 0 V a n d a p p r o x 5 V o r m o r e
appear alternatelY?
Check for loos€ TCM connedors
lI nec€ssary, substitute a known'
good TCM and recheck.
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