The unit functions except for a dead display. I have triied resetting the unit. The dimmer, battery, and ignition circuit fuses powering the unit are all good.

I would check the fuses first. Headlights are typically on a separate fuse then the parking lights. If the fuse is fine check and see if the Bulb is burnt out but it is rare for both lights to go out at the same time.

DTC P1682 Ignition 1 Switch Circuit 2
The ignition 1 voltage of the ignition main relay is more than 3 volts different than the ignition 1 voltage of
the powertrain relay for more than 2 seconds.

There are 2 ignition 1 voltage circuits supplied to the engine control module (ECM). The first ignition 1
voltage circuit is provided by the powertrain relay through a fuse. This ignition 1 voltage circuit supplies
power to all the internal ECM circuits associated with the throttle actuator control (TAC) operation. The
ignition main relay provides the second ignition 1 voltage circuit to the ECM through a fuse. This ignition
1 voltage provides power to other internal ECM circuits, except those associated with TAC operation.
The ECM continuously monitors the voltage level difference between the 2 circuits.

Have you checked the dash dimmer switch to see if it's on fully?

Do you know anything about automotive electronics ? Electronic control modules .
Headlamp ON/OFF control is determined by the body control module (BCM) by a signal on the headlamp switch on input circuit when the headlamp switch is in the HEAD position. When the headlamp switch is in the AUTO position, the BCM determines headlamps ON/OFF by the voltage from the ambient light sensor.
If the headlight switch is left in the ON position, the inadvertent power control feature will turn OFF the headlights approximately 10 minutes after the ignition switch is turned to the OFF position. If the driver places the headlight switch in the ON position after the ignition switch has been turned OFF, or if the ignition switch is in the ACCY position, the headlights will remain ON until turned OFF or the battery runs dead.
The high beam indicator is illuminated when the instrument cluster receives a GMLAN serial data message from the BCM that the high beams are illuminated.
High Beams
The high beam headlamps receive voltage from the headlamp high relay located in the underhood fuse block. The BCM controls the relay on the headlamp high beam relay control circuit. High beam control is determined by a signal on the headlamp dimmer switch signal circuit from the multifunction switch. When the headlamp dimmer switch signal circuit is grounded, the BCM grounds the headlamp high beam relay control circuit, illuminating the high beam headlamps. The right and left high beam circuits are independent and are fused independently in the underhood fuse block.
Low Beams - Standard
The low beam headlamps receive voltage from the headlamp low beam relay located in the underhood fuse block. The BCM controls the relay on the headlamp low beam relay control circuit. Low beam control is determined by a signal on the headlamp dimmer switch signal circuit from the multifunction switch. When the headlamp dimmer switch signal circuit is open, the BCM grounds the headlamp low beam relay control circuit, illuminating the low beam headlamps. The right and left low beam circuits are independent are fused independently in the underhood fuse block.

Hooking up a factory scan tool an checking DTC'S - diagnostic trouble codes would be the very first step in trouble shooting this problem .
DTC B257A 00: Headlamp Switch Input Signal Mismatch
DTC 2575 00: Headlamp Control Circuit

Headlamps
The headlamps are operated when the driver places the headlamp switch in the HEADLAMP position. The LT HDLP and RT HDLP fuse in the IP fuse block, supply battery positive voltage to both the left and right headlamps. The low beam and high beam circuits continue to the headlamp switch. Depending on the position of the dimmer switch, either the low or high beam circuit will now have a path to ground. Ground is provided at G204. The low beam and high beam circuits also provide the body control module (BCM) with both low and high beam inputs. The headlamp switch includes the dimmer and the flash-to-pass switch.
If the headlight switch is left in the HEADLAMP position, the headlights will remain on until turned off or the battery runs dead.
Daytime Running Lamps (DRL)
Any function that turns on the headlights will cancel the daytime running lamps operation. The LT HDLP fuse in the IP fuse block supplies battery positive voltage to the daytime running lamp (DRL) relay coil circuit. The DRL relay switch contacts are connected to the low beam circuit. When the headlamp switch is placed in the OFF position, the BCM will turn on the daytime running lamps. The BCM energizes the DRL relay, closing the switch contacts and grounding the low beam circuit at G204. The DRL illuminate the low beam headlights at a reduced intensity. The DRL will operate when the ignition switch is in the RUN position, the gear selector is not in the PARK position and the parking brake is released. When these conditions have been met the DRL will illuminate.
DRL operation in Manual Transmission equipped vehicles will occur when the ignition switch is in the RUN position, and the parking brake is released.

Probably the dimmer switch . But without testing that would be just a guess . Turnning the headlamps on Any function that turns on the headlights will cancel the daytime running lamps operation..
No ,don't think the DRL relay has anything to do with it .

View wiring diagrams an testing the electrical circuits at the dimmer switch would be the proper way to diagnose .

The Bike Technicians Tactic

Phase1

An electrical inspection on the bike should produce results. First, the bike battery powers the entire lightening systems mentionable as ignition, meter readings, head lamps, signal indicators. However, the battery provides the power supply to several entities though also significant is the fuse box containing circuit protection coils. Inserting the bike key into the ignition to perform start mode displays the capacity power circuits. A charged battery should display an indication in the meter reading area also known as bike dashboard grading. A malfunctioning start mode on inserting key in ignition may be traceable several locations on the electrical circuits. Attempting to repair the electrical power of the bike usually requires batter power power test kit. The test kit ascertains the battery power making possible progress to the remaining electrical circuits. Test kit also ascertains the fuse box circuit functionality either with fuses still intact or extracted allowing for the next progress level. An observation tour of the bikes electrical wiring kits from battery hold through fuse box compartments to each lightening display area either headlamps, indicators, and meter reading should produce results of any visible damages that may require repairs after the electrical inspection has been performed. Once any faults were observed on the electrical channels, repair mode is the next level. A dull battery either may have been depleted completely of durational capacity requiring another for replacement. Alternately, a depleted power supply due to prolonged storage may require charge functionalities. Usually, a device capacapble of restoring a battery of electrolytes is resorted for charger ability. The type of battery may require constuents either liquid cathode replenishment in the battery entrapment area prior to charging feature is assumed with electrolyte machine. Once the battery has regained full functionality makes way the next repair task. The fuse box may have simply required replacement fuses either as missing or burnt out. A fuse box usually contains additional spare for replacement functionalities. An alternate arrangement at acquiring fuses on the auto mart may replace the burnt devices. The next electrical task is wiring fixtures achievable by mending broken cords with appropriate electrician's tapes else malfunctions may remain. Alternately, a worn-out electrical wire is replaceable by acquiring the entire extension lengthwise between significant areas. The last remaining electrical units are lightening indicators consisting of bulbs or luminescent displays reflectors. Observe the blub areas either by loosening covers to inspect for observable burnouts else the entire electrical circuitry is ready for functionality observations with separate entities.

Engine Technicians Tactic

PHASE 2

A bike engine inspection includes observation for indications of malfunction. Any fluid residue is indication of problem areas. Where oil leaks usually requires engine block inspections. A bike engine consists of an entrapment compartment where mechanical combustion takes place. First, the entire observable block consists of an external coating known as engine bloc housing internal component of pistons, rings, and fastens known as cylinder heads. A bike engine has every component embedded within requiring technical expertise to achieve an inspection. Once deciding on the engine task requirements, acquire a tool box with the appropriate componements as first requirement before engine works is commence able. Second, the bike may require an area environment as workshop requirement to attain engine inspections. Third, bike engine are least bulky compared with vehicle engines however assistance would complement the inspection phase. Prior to inspecting the bike engine, a strap mechanism has to be assumed to achieve expert maneuverability also as safe precaution. Unless parts hinder maneuverability at engine locations, the only removable components should be the engine. First, start with disjointing the spark plug cables to acquire accessibility to plugs imbedded on the cylinder heads. The plugs require tools to loosen thereby exposing the combustible area. Once the spark plugs are exposed, two alternatives are likely. First, a spark plug may have gathered rust residue only requiring cleaning to attain regular capacity. The pin area of the spark plug may have been twisted due to overheating and slight melting dislocation. Usually cleaning the residue from old plugs may simply expose the ignitable capacities. However, an observation of twisted plug pin may require twisting back in place to achieve full ignitability once bike engine starts. A bike engine bloc has the pistons as combustibles or blasters of fuel gasoline. The rings perform as strap fasteners whenever the pistons move about combustibility. Usually, the engine entrapment components would have collected residue requiring clearing. Also, pistons together with rings may require replacements either as worn-out due to prolongs tasks or overexerted biker features.

Hi.

This is a common problem with this model.

The LCD has a dimmer circuit that can be responsible, in some case it is not the dimmer regulation, but the LCD control circuit itself. In that case you have no LCD backlight and the display is almost unreadable. If that is the problem, changing dimmer settings with procedure below will not help.

Most of the time the problem is dimmer regulation.

About dimmer regulation:

Try disconnecting the unit power cord for ten minutes and connect back.
Try holding down CD or CLOCK button and pressing at the same time the volume buttons. This procedures regulates Bose dimmers setting in a scale from one to 9. The dimmer has separate settings for medium and low brightness. Set both to 5 if you want to disable dimmer settings.

Reset process should be listed in the owners manual.

Should be something like turn car to on(not running) press trip button twice, turn to off and hold trip button till it resets.

The circuit board is broken.
I was trying to find out about setting the display dimmer option. I found someone that had a manual and was told to set/reset the "dimmer on/off" by pressing the function button repeatedly while the unit is powered off. When dimmer showed on the faceplate press up or down to set or reset the dimmer option. This was done in a dark closet as the display was so dim. Anyway, setting dimmer to on/off made no difference in the brightness of the display. Oh well. . . BTW, I found that the manual is not a free download and can cost between $18 - $40 on the internet - geeeeee whiz, Pioneer is not a user friendly company.

Are all of these not working ?
• Air temperature switch
• Cigar lighter lamp
• Door switches
• Driver information center (DIC) switch
• Headlamp switch
• Head-up display (HUD) switch
• Heated seat switches
• HVAC control assembly
• Instrument panel cluster (IPC)
• Memory function switch
• Radio
• Steering wheel controls
• Window switches

Interior Lamps Dimming
This group of interior lighting includes lamps which may be dimmed. This group uses a combination of class 2 controlled illumination and incandescent lamps:
• Air temperature switch
• Cigar lighter lamp
• Door switches
• Driver information center (DIC) switch
• Headlamp switch
• Head-up display (HUD) switch
• Heated seat switches
• HVAC control assembly
• Instrument panel cluster (IPC)
• Memory function switch
• Radio
• Steering wheel controls
• Window switches
For the interior lighting to be dimmed the following conditions must be met:

Here is a discription of how they work ,factory service info.
• A low light level has been detected by the dash integration module (DIM)
• Headlamp switch is placed in to the PARK or HEAD position
• Ignition switch is placed in the ON position
Then all class 2 displays and all incandescent back lighting will be illuminated to the level set by the instrument panel (I/P) dimmer switch. When the I/P dimmer switch is moved from MIN to MAX, all class 2 displays and all incandescent back lighting respond from minimum intensity to maximum brightness.
The DIM supplies battery positive voltage to the coil side of the PRK LP relay in the rear fuse block.
When the I/P dimmer switch is moved from MIN to MAX, then the instrument panel module (IPM), W/CJ2, or climate control panel (CCP), W/C67, applies a message to the class 2 communication circuit to the DIM. The DIM then applies a ground to the park lamp relay control circuit. This energizes the PRK LAMP relay and allows battery positive voltage to be applied through the DIMR fuse to the DIM. The DIM then illuminates the following incandescent lamps through the incandescent dimming output circuit:
• Cigar lighter lamp
• DIC Switch
• Headlamp switch
• HUD switch
• HVAC control assembly
• IPC
• Radio
• Steering wheel controls
The DIM also applies a message to the following class 2 controlled illumination components:
• Drivers door module (DDM)
• HVAC control assembly
• IPC
• Radio
The DDM will then send a message through the simple bus interface (SBI) to the RH front door module (RFDM). The door modules will then illuminate the following components through the incandescent dimming output circuit:
• Air temperature switch
• Heated seat switches (W/KA1)
• Memory function switch (W/A45)
• Power door lock switches
• Power window switches
The ground for these components are provided from the DDM and RFDM.
The following components are grounded at G200:
• Headlamp switch
• HVAC control assembly
• Radio
• Steering wheel controls
The following components are grounded at G201:
• Cigar lighter lamp
• DIC Switch
• HUD switch

Having the vehicle checked for DTC'S - diagnostic trouble code's would probably be your best course of action .
DTC B2556 (1)
The I/P dimmer switch is a potentiometer. The instrument panel module (IPM) determines the control setting based on the voltage from the I/P dimmer switch. The IPM sends out a class 2 message to the dash integration module (DIM). The intensity of the interior backlighting shall be adjustable when ever the park lamps are on. The intensity of the vacuum florescent displays shall only be adjustable when it is night and the park lamps are active.
DTC B2627
DTC B2628
Circuit Description
The I/P dimmer switch is a potentiometer. It is powered by the HVAC control module. The HVAC control module determines the level of dimming desired based on the voltage from the I/P dimmer switch. The HVAC control module converts the I/P dimmer switch feed back voltage to a digital signal and puts it on the Class II communication bus.

Dash Integration Module (DIM)
The DIM is wired to the class 2 serial data line. The various DIM input and output circuits are described in the corresponding functional areas as indicated on the DIM electrical schematics.
The DIM functions include the following:
• Control of headlights and exterior lamps
• Horn relay control
• Interior lamps incandescent dimming
• Lamps On signal with wiper/washer
• Power moding control over Class 2 serial data line
• Steering wheel controls
• Storage of the clock settings and, sending a message out on the class 2 serial data circuit in response to requests from other modules

Your best bet ,take your vehicle to a qualified repair shop.