Inspection of FWD Switch

INSPECTION OF FWD SWITCH
DIAGNOSIS:
The LED does not come on even if FWD switch is ON. The FWD switch circuit is open or short.





WIRING DIAGRAM:


CHECK SPARE FUSE.
Is the spare fuse OK?
Yes
Go to next step

No
Replace the fuse.


CHECK FWD SWITCH.
Connect the Vehicle Diagnostic Interface to data link connector.
When the fuse is inserted to FWD switch, does the LED light up?
Yes
Go to CHECK COMBINATION METER

No
Go to CHECK HARNESS CONNECTOR BETWEEN TCM AND FWD SWITCH

CHECK COMBINATION METER.
Does the FWD indicator light illuminate?
Yes
Go to INSPECTION FOR CRUISE CONTROL SWITCH.

No
Go to CHECK HARNESS CONNECTOR BETWEEN TCM AND COMBINATION METER


CHECK HARNESS CONNECTOR BETWEEN TCM AND FWD SWITCH.
Turn the ignition switch to OFF.
Disconnect the connector from TCM.
Measure the resistance of harness between TCM and FWD switch connector.
Connector & terminal
(B56) No. 17 - (F27) No. 36:
Is the resistance less than 1 Ohms?
Yes
Go to CHECK HARNESS CONNECTOR BETWEEN FWD SWITCH AND CHASSIS GROUND

No
Repair the open circuit in harness between TCM and FWD switch connector.


CHECK HARNESS CONNECTOR BETWEEN FWD SWITCH AND CHASSIS GROUND.
Measure the resistance of harness between FWD switch and chassis ground.
Connector & terminal
(F27) No. 35 - Chassis ground:
Is the resistance less than 1 Ohms?
Yes
Go to CHECK HARNESS CONNECTOR BETWEEN TCM AND FWD SWITCH

No
Repair the open circuit in harness between FWD switch connector and chassis ground.


CHECK HARNESS CONNECTOR BETWEEN TCM AND FWD SWITCH.
Measure the resistance of harness connector between TCM and body to make sure that circuit does not short.
Connector & terminal
(B56) No. 17 - Chassis ground:
Is the resistance more than 1 MOhms?
Yes
Go to CHECK INPUT SIGNAL FOR TCM

No
Repair the short circuit in harness between TCM and FWD switch connector.


CHECK INPUT SIGNAL FOR TCM.
Turn the ignition switch to OFF.
Connect the connector to TCM.
Turn the ignition switch to ON.
Measure the signal voltage for TCM while installing the fuse to FWD switch connector.
Connector & terminal
(B56) No. 17 (+) -Chassis ground
Is the voltage less than 1 Volt?
Yes
Go to next step

No
Go to CHECK OUTPUT SIGNAL EMITTED FROM TCM

CHECK INPUT SIGNAL FOR TCM.
Measure the signal voltage for TCM while removing the fuse from FWD switch connector.
Connector & terminal
(B56) No. 17 (+) - Chassis ground
Is the voltage 6 - 9.1 Volts?
Yes
Go to CHECK HARNESS CONNECTOR BETWEEN TCM AND COMBINATION METER

No
Replace the TCM.


CHECK HARNESS CONNECTOR BETWEEN TCM AND COMBINATION METER.
Turn the ignition switch to OFF.
Disconnect the connector from TCM and combination meter.
Measure the resistance of harness between TCM and check connector.
Connector & terminal
(B56) No. 14 - (i10) No. 4:
Is the resistance less than 1 Ohms?
Yes
Go to next step

No
Repair the open circuit in harness between TCM and combination meter and poor contact in coupling connector.


CHECK HARNESS CONNECTOR BETWEEN TCM AND COMBINATION METER.
Measure the resistance of harness connector between TCM and chassis ground to make sure that circuit does not short.
Connector & terminal
(B56) No. 14 - Chassis ground:
Is the resistance more than 1 MOhms?
Yes
Go to CHECK OUTPUT SIGNAL EMITTED FROM TCM

No
Repair the short circuit in harness between TCM and combination meter connector.


CHECK OUTPUT SIGNAL EMITTED FROM TCM.
Turn the ignition switch to OFF.
Connect the connector to TCM and combination meter.
Turn the ignition switch to ON.
Measure the signal voltage for TCM while installing the fuse to FWD switch connector.
Connector & terminal
(B56) No. 14 (+) - Chassis ground
Is the voltage less than 1 Volt?
Yes
Go to next step

No
Go to CHECK FUSE

CHECK OUTPUT SIGNAL EMITTED FROM TCM.
Measure the signal voltage for TCM while removing the fuse from FWD switch connector.
Connector & terminal
(B56) No. 14 (+) - Chassis ground
Is the voltage 6 - 9.1 Volts?
Yes
Go to CHECK FUSE

No
Replace the TCM.


CHECK FUSE.
Is the fuse OK?
Yes
Go to CHECK POOR CONTACT

No
Replace the fuse.


CHECK POOR CONTACT.
Is there poor contact in FWD switch circuit?
Yes
Repair the poor contact.

No
Replace the TCM.