ELECTRICAL SYSTEM CONTINUED
Switches will provide one of the following types of inputs to the ECM:
Switches are devices that have two contact states, either open or closed.
When switch contacts are open, no signal is provided tothe corresponding input of the ECM. This "no signal"
condition is also referred to as floating.
When switch contacts are closed, either a ground signalor +battery signal is provided to the corresponding
input of the ECM.
When a switch provides two inputs to the ECM, the ECM will usually monitor the switch circuits for diagnostics. If a
switch provides only one input to the ECM, the ECM will not monitor the circuit for diagnostics.
The ignition switch sends three battery inputs to the ECM depending on the position of the ignition switch. When
the ignition switch is in the ON position, +battery power is supplied to the ECM at connector contacts J1-1 and
J1-14. When the ignition switch is in the START position, +battery power is supplied to the ECM at connector
contact J2-1. These inputs allow the ECM to monitor the state of the ignition switch.
In order for the ECM to energize the output for the start relay, the ECM must detect the correct states for the
Ignition switch in the START position
FNR position sensor inthe N position (Neutral)
Parking brake switch in the ON position
When the ECM detects that these conditions are correct, the start relay will be energized which will send battery
Figure 6. Ignition Switch.