Mil Circuit Troubleshooting - Honda EP3 Service Manual

MIL Circuit Troubleshooting
1. Connect an OBD ll scan tool/Honda PGM Tester
( s e e p a g e 1 1 - 3 ) .
2. Turn the ignition switch ON (ll) and read the OBD ll
scan tool/Honda PGM Tester.
Does the OBD ll scan tool/Honda PGM Tester
communicate with the ECM?
YES Go to step 3.
NO Go to troubleshooting
"
DLC Circuit
T r o u b l e s h o o t i n g " ( s e e p a g e 1 1 - 1 0 9 ) .
3. Check the OBD ll scan tool/Honda PGM Testerfor
DTCs.
Are any DTCs ind icated?
YES Go to the DTC Troubleshooting Index.
NO-Go to step 4.
4. Turn the ignition switch OFF.
5 . 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 ) a n d w a t c h t h e
l M a l f u n c t i o n I n d i c a t o r L a m p ( M l L ) .
Does the MIL come on and stay on for more than
20 seconds aftet turning the ignition switch
oN (tr)?
YES lf the MIL always comes on and stays on, go
to step 76. But if the lMlL sometimes works
normally, first check for these problems.
. An intermittent short in the wire between the
E C I M ( E 2 9 ) a n d t h e d a t a l i n k c o n n e c t o r ( D L C ) .
. An intermittent short in the wire between the
E C M ( E 3 1 ) a n d t h e g a u g e a s s e m b l y .
NO lf the MIL is always off, go to step 6. But if the
lvllL sometimes works normally, first check for
these problems.
. A l o o s e N o . 1 0 M E T E R ( 7 . 5 A ) f u s e i n t h e u n d e r
dash fuse/relay box.
. A l o o s e N o . 2 0 l G ( 4 0 A ) ( C a n a d a : 5 0 A ) I u s e i n t h e
under-hood fuse/relay box.
. A i o o s e N o . 6 E C U ( E C M ) ( 1 5 A ) f u s e i n t h e u n d e r -
hood fuse/relay box.
. A l o o s e N o . 1 7 F U E L P U M P ( 1 5 A ) f u s e i n t h e
under-dash fuse/relay box.
. A p o o r c o n n e c t i o n a t E C M t e r m i n a l E 3 1 .
. An intermittent open in the GRN/ORN wire
b e t w e e n t h e E C M ( E 3 1 ) a n d t h e g a u g e a s s e m b l y .
. An intermittent short in the wire between the
ECM (A21) and the manifold absolute pressure
( M A P ) s e n s o r .
. An intermittent short in the wire between the
ECI\4 (A20) and the throttle posilion (TPi sensor.
. An intermittent short in the wire between the
ECM (E5) and the fuel tank pressure (FTP) sensor.
6. Turn the ignition switch OFF.
7 . 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 ) .
ls the low oil pressure light on?
YES Go to step 10.
N O - G o t o s t e p 8 .
8 . I n s p e c t t h e N o . 1 0 l \ 4 E T E R ( 7 . 5 A ) f u s e i n t h e u n d e r -
dash fuse/relay box.
ls the luse OK?
YES Go to step L
N O R e p a i r s h o n i n t h e w i r e b e t w e e n N o . 1 0
M E T E R ( 7 . 5 A ) f u s e a n d t h e g a u g e a s s e m b l y . A l s o
r e p l a c e t h e N o . 1 0 M E T E R { 7 . 5 A ) f u s e . l
9. Inspect the No. 20 lG1 (40A) (Canada: 50A) fuse in
the under-hood fuse/relay box.
ls the f use OK?
YES Repair open in the wire between the No. 20
l G ( 4 0 A ) { C a n a d a r 5 0 A ) f u s e a n d t h e g a u g e
assembly. lf the wire is OK, test the ignition switch
{see page 22 53).
N O R e p a i r s h o r t i n t h e w i r e b e t w e e n N o . 2 0 l G
( 4 0 A ) l C a n a d a : 5 0 A ) f u s e a n d t h e u n d e r ' d a s h f u s e l
r e l a y b o x . A l s o r e p l a c e t h e N o . 2 0 l G ( 4 0 A i
( C a n a d a : 5 0 A ) f u s e . I
( c o n r ' d )
11-97