Suzuki GRAND VITARA 2005 Service Manual page 405

Step
4 Check brake fluid level switch
1) Turn ignition switch to OFF position.
2) Disconnect brake fluid level switch connector.
3) Check for proper connection at each terminal of brake
fluid level switch connector.
4) If OK, then check brake fluid level switch referring to
"Brake Fluid Level Switch Inspection: in Section 9C in
related manual".
Is check result OK?
5 Check brake fluid level switch circuit
1) Disconnect BCM connector.
2) Check for proper connection to BCM connector at "G31-
7" terminal.
3) If OK, then check resistance between "G31-7" terminal
and vehicle body ground.
Is resistance infinity?
6 Check BCM
1) Connect brake fluid level switch connector and BCM
connector.
2) Check voltage at "G31-7" terminal of BCM referring to
"Inspection of BCM and its Circuits: in Section 10B".
Is voltage in good condition?
DTC C1020: Master Cylinder Pressure Sensor Power Supply Failure
DTC Detecting Condition and Trouble Area
DTC Detecting Condition
Power supply voltage to master cylinder pressure sensor
in ESP® hydraulic unit / control module assembly is too
low.
DTC Troubleshooting
1) Turn ignition switch to OFF position.
2) Check for proper connection from harness to ESP® control module.
3) If OK, substitute an ESP® hydraulic unit / control module assembly with correct part number.
4) Recheck system.
Action
Electronic Stability Program:
Yes
Go to Step 5.
Go to Step 6.
Substitute a known-
good ESP® hydraulic
unit / control module
assembly and recheck.
Trouble Area
• ESP® control module
4F-28
No
Replace brake fluid
level switch.
"BLKL/RED" wire circuit
short to ground.
Check BCM power and
ground circuit. If circuit
is OK, substitute a
known-good BCM and
recheck.
S5JB0B4604061