Suzuki 2000 Grand Vitara SQ625 Service Manual page 194

STEP
4 HO2S Heater Control Circuit check:
(1) With ignition switch OFF, install HO2S heater relay.
(2) With ignition switch ON leaving engine OFF, check
voltage between C51-3-16 and ground.
Is the voltage 10 – 14 V?
Fig. for STEP 2, 3
ACTION
ENGINE (H25 ENGINE) 6-1-83
YES
Substitute a known-
good ECM (PCM)
and recheck.
a
NO
Faulty HO2S heater
relay or "P/W" wire
shorted to ground
circuit.
If OK, substitute a
known-good ECM
(PCM) and recheck.
a. HO2S heater relay