Suzuki Baleno Manual page 1440

6-2-92 ENGINE GENERAL INFORMATION AND DIAGNOSIS (J18 ENGINE WITH WU TWC)
TROUBLESHOOTING (DTC P1500)
STEP
1 Was ENGINE DIAG. FLOW TABLE performed?
2 Check for voltage at terminal C20-5 of ECM connector
connected, under the following condition.
While engine cranking : 6 – 14 V
After starting engine
Is voltage as specified?
ACTION
: 0 – 1 V
YES
Go to Step 2.
Poor C20-5 connection
or intermittent trouble.
Check for intermittent
referring to "Intermittent
and Poor Connection"
in section 0A.
If wire and connections
are OK, substitute a
known-good ECM and
recheck.
NO
Go to ENGINE
DIAG. FLOW
TABLE.
"B / Y" circuit open.