Suzuki's 1999/2000/2001 Wiring Diagram Manual calls out
five diodes for the Grand Vitara. The 2001 Chevy service
manual only calls out three. This is why:


Suzuki gives each diode a number. Diode #1 plugs into connector E54.


The diode in E54 allows the tail light relay and the rear defogger
to share the idle-up input on pin 15 of the 1999/2000 PCM.



Apparently the PCM was upgraded in 2001. The rear defogger
remained on pin 15 but the tail light relay was moved to its own
idle-up input on pin 29. The "sharing" diodes were no longer
needed so they don't show up in the 2001 Tracker schematic.



Chevy calls Diode #2 the "DRL diode." It's an odd name because it has nothing to do with DRL module. In a similar
manner to Diode #1, it allows the coil of the headlight relay to share power from the two 15-amp headlight fuses.
If one fuse blows, the other fuse will continue to power the headlight relay so at least one headlight will continue
to operate. If the bottoms of the fuses were tied together without the intervening diodes, the headlights would still
work normally. The diode only becomes essential if one of the headlamp filaments shorts out. Instead of popping
one fuse when the current reached 15 amps both fuses would blow when the current reached 30 amps. The DRL
diodes let you drive home with one headlight on a moonless night.

Diode #5 (also shown above) does not exist on the Tracker. Fog lights were an option on the Grand Vitara but not
the Chevy. When the headlight switch is in the HEAD position, ground is passed up through the switch to the fog
light switch and up through Diode #5 to energize the headlight relay. For some reason Suzuki did not want the
ground from the Ambient Light Sensor (aka Auto Light Controller) to have any influence on the fog light switch.
Diode #5 ensures the ALS can turn on the headlights but not the fog lights. The Tracker doesn't need this diode
so it does not show up in the Chevy service manuals.


Chevy calls Diode #3 the "Shift Lock Diode" and that's appropriate.
When the shift lock solenoid is energized, battery current passing
through the coil builds up a magnetic field around the coil. A 12-volt
drop is felt across the coil, positive at pin 3 and negative at pin 6.
When current to the shift lock solenoid is interrupted, the magnetic
field collapses. This collapse induces a voltage across the coil with
a polarity opposite to it's original state in an attempt to keep the
current flowing in the same direction. This induced voltage is
positive at pin 6 and negative at pin 3. When the solenoid was
energized, the diode acted like an open and did nothing. But now
that the polarity across the coil is reversed, the diode acts like a
short circuit feeding any induced current back into the coil. The
copper wire in the coil dissipates that energy as a harmless
amount of heat. The diode is essential because the amplitude
of the induced voltage is determine by the speed at which the
field collapses (rate of change). As the time of collapse
approaches zero the induced voltage approaches a very big
number -- many times higher than battery voltage. The duration
of that voltage is very short but it produces a spike that can
destroy solid-state devices and most of the Tracker's engine
sensors are solid-state devices.


Chevy calls Diode #4 the "Dome Lamp Diode" which is again odd because it had nothing to do with dome light.


When the audible alarm module in the instrument panel sees the key in the ignition and the driver's door open, it starts
that nagging beep-beep-beep reminder. If the Dome Light Diode were not present, any of the other four doors left open
would also initiate the chime when the key was left in the ignition. If think you would like that just jumper around the diode.

Here's where diodes are located.