2004 Chevrolet Express 3500 2004 3500 Chevrolet Express Instrument light problem
2004 3500 Chevrolet Express Instrument light problem
What is your question?
Light switch on my 2004 3500 Chevrolet express has four positions, 1- Defeat, 2- Daytime Running Lamps,
3- Parking Lamps & 4 –Headlamps. The Instrument lamps go on when the Daytime Running Lamps and the
Headlamps positions are selected. The Instrument lamps will not come on when the Daytime Running Lamps
position is selected. I have checked the Instrument Panel Brightness Control & on off control and it will not
correct the problem. When in the Daytime Running Lamps position the running lights come on when the auto is in drive.
I have checked the fuses # 8 & 9 under the hood and the fuses are good. Do you have any suggestions as to what the
problem could be or what I can check to isolate and identify the instrument light problem.
Thank you,
Bill La Grassa e-mail ( blagrassa@rfrontiernet.net )
PS: The owners manual indictes instrument lights should be on with the light switch in the Daytime Running Lamps position and the truck in drive.
Do you have any suggestions??? Bill
The run lights come on
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I am not quite sure I understand your question. I think you are asking why the instrunment panel backlighting does not come on with the daytime running lights. I do not think it should. You only need the back lighting at night, when the park or headlights are on. The BCM controls the backlighting based on an imput from the headlight switch. The backlighting for the guages, radio, a/c control, window switches, etc.. should all be on at the same time. If that is the case, I would think all is OK. Here is the technicial description of the system in question -
Interior Lamps Dimming:
The second group includes lamps which may be dimmed. This group may use a combination of vacuum fluorescent (VF) illumination and incandescent lamps.
When the ignition switch is turned to the RUN position, the radio's VF displays turn on at maximum brightness. When the park lamps are on, all incandescent back lighting turn on at the dimming level indicated by the instrument panel (I/P) dimmer switch. At the same time all VF displays dim to match the indicated dimming level. The panel dimmer switch potentiometer is an input to the BCM. When the driver selects a dimming setting by moving the I/P dimming switch potentiometer, all incandescent back lighting lamps are provided with a specific voltage. When the I/P dimmer switch is moved from MIN to MAX, all VF displays, as well as all incandescent back lighting respond from minimum intensity to maximum brightness in response to the I/P dimmer switch.
The following switches and components have dimmable back lighting:
• The traction control switch
• The instrument panel cluster (IPC)
• The radio controls
• The headlamp and panel dimmer switch
• The HVAC control assemblies
• The inflatable restraint disable switch
• The tow/haul switch
• The window and door lock switches
• The rear heater switch
• The rear seat audio control
The I/P cluster illumination lamps, various switches and control assemblies receive voltage and are controlled by the BCM on the instrument panel lamps dimming control circuit and the backlight lamps control circuit.
Voltage for the LED dimming signal, instrument panel lamps dimming control, as well as the backlight lamps control circuits is from the TBC 3 fuse 16 in the underhood fuse block directly through the BCM to these circuits.
