Checking the Brake Light Switch Operation

Checking Brake Light Switch Operation, Steps 1 & 3:

1 Connect an ISAT scan tool, contact the SFI system and enter command code EE62.

The status of the system is displayed on the ISAT:

^ Brake pedal depressed PAE62-ON. If not, go to point 2.

^ Brake pedal not depressed~ PAE62-OFF. If not, go to point 5.

2 Check whether fuse FA24 is intact. Also check whether the brake lights work. Change the fuse if it has blown. Take remedial action if the brake lights do not work.

If the fuse is OK, continue as described below.

3 With the ignition switched off, connect a break-out box to the ECM wiring harness (ECM disconnected).

With the ignition switch in the Drive position, check whether battery positive voltage is present on pin 15 of the ECM when the brake pedal is depressed.

If it is, the ECM may be faulty. Review "Before Replacing ECM."

Checking Brake Light Switch Operation, Steps 4, 5, 6:

4 Check whether voltage is present on pin 1 of the brake light switch when the switch is activated. If it is not, replace the brake light switch.


If the switch is OK. check the lead to pin 15 of the ECM (ignition switched off) for continuity/shorting to ground.


Take remedial action if the wiring/connectors are faulty.

5 Check whether voltage is present on pin 1 of the brake light switch when the switch is not activated. If voltage is present, replace the brake light switch.

If the switch is OK, continue as described below.

6 With the ignition switched off, connect the break-out box to the ECM wiring harness (ECM disconnected).


Turn the ignition switch to the Drive position and check the lead to pin 15 of the ECM for shorting to battery positive voltage.

Take remedial action in the event of faulty wiring/connectors or any component connected to grounding point J32 which might be the cause of voltage being applied to the circuit.

7 If the wiring is OK, the ECM may be faulty. Review "Before Replacing ECM."