Weird dash light problem. the backlights to illuminate the dash intermittently go off and the radio light goes dim when they go off, the dimmer seems to function fine when the lights work, almost seems like a grounding issue. the pointers that move up and down in the tach and speedometer stay lit also the lights in the center console go out with the dash lights ,cant find a bad fuse dave

STOP and PARK LPS will be tail lights.

ILLUM and GAUGES will.be dash lights.



STOP
Stop/CHMSL, Stoplamps

GAUGES
IP Cluster, DRL Relay, DRL Module, HDLP Switch, Keyless Entry Illumination, Low Coolant Module, CHIME Module, DRAB Module

PARK LPS
License Plate Lamp, Parking Lamps, Taillamps, Front Sidemarkers, Glove Box Ashtray

ILLUM
LP Cluster, HVAC Controls, RR HVAC Controls, IP Switches, Radio Illumination, Door Switch Illumination

. The illumination is controlled by the BCM - body control module .
Interior Lamps Dimming
This group includes lamps which may dim. This group may use a combination of vacuum fluorescent (VF) illumination and incandescent lamps.
• HVAC control module, head assembly
• Rear HVAC control module, head assembly
• Radio
• Rear seat Audio
• The instrument panel cluster (IPC)
• The PRNDL lamp, with the exception of the current gear select position
• Power window switches
• Various switches
When the ignition switch is turned to the ON position, the VF display, radio, turns 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. When the headlamp switch is placed in the PARK position, the park lamp supply voltage circuit provides an input to the body control module (BCM). The BCM then supplies voltage to the I/P dimmer switch through the I/P dimming lamps control circuit. The setting of the I/P dimmer switch determines the amount of voltage that the I/P dimmer switch supplies to the BCM through the I/P dimming lamps low reference circuit. The BCM then sends a pulse width modulation (PWM) voltage to all the interior lamps. All the VF and incandescent back lighting lamps are provided a specific voltage and are then grounded. When the headlight switch is turned to the park lamp or headlamp position, all incandescent back lighting turn ON at the dimming level indicated by the I/P dimmer switch. 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.


Do you know what DTC'S - diagnostic trouble codes are ? Codes set in the BCM
DTC B2610 00: Passenger Compartment Dimming 1 Circuit
DTC B2615 00: Passenger Compartment Dimming 2 Circuit
DTC B2652 00: Passenger Compartment Dimming 3
Circuit/System Description
The instrument panel (I/P) lamp dimmer switch is used to increase and decrease the brightness of the interior backlighting components. The I/P dimmer switch provides a voltage signal that will increase as the brightness of the lights are increased and decrease as the brightness of the lights are decreased. The body control module (BCM) provides a low reference signal and a B+ voltage reference to the I/P dimmer switch. When the I/P dimmer switch is placed in the desired position, the dimmed voltage setting is applied from the I/P dimmer switch through the I/P dimmer switch signal circuit to the BCM. The BCM interprets the signal and applies the dimmed voltage to the I/P lamps supply voltage circuit and the interior backlighting components dim to the requested level. Ground for the I/P dimmer switch is provided at G201.

sunroof fuse 1 20amp / power windows - circuit breaker 25 amp
both of these are located in the instrument panel fuse box .

bim or DIM ? the dimmer switch ! Interior Lamps
The interior lamps consists of two groups, lamps that can not be dimmed and lamps that can be dimmed. This first group consists of lamps that may not be dimmed. This includes those lamps that may be manually turned on by placing the interior lamp switch to the DOME position, or by opening a door or a compartment:
• Door courtesy lamps
• Footwell courtesy lamps
• Instrument panel (I/P) compartment lamp
• Overhead console courtesy lamps
• Reading courtesy lamps
• Rear compartment courtesy lamp
• Roof rail courtesy lamps
• Sunshade vanity mirror lamps

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:
• 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
• IPC
• Radio
• Steering wheel controls
The following components are grounded at G201:
• Cigar lighter lamp
• DIC Switch
• HUD switch

The sensor is usually located on the top of your dashboard. You might see it if you look into your vehicle through your windshield at your dash.
I have seen( one time ) that a gps was bright enough that it caused the dash lights not to come on because the sensor thought it was light outside.
Or you could have gotten a bad sensor.

The lights on the radio are dimmed with the instrument panel dimmer control so usually they are fed with a separate 12 volt signal that is separate from the main radio power. It may have a separate fuse but may not. If it's not a fuse it could be a loose connector going to the radio, assuming the rest of the instrument panel lights are working correctly. I suppose it is also possible that the dimmer control has two sections, one for the radio and one for the panel lights, and the section for the radio is bad. Run the dimmer control back and forth stop to stop a few times, push on it etc. to see if that effects it. I suspect it is somewhere in the dimmer circuit.

It's not high and low beam, it's the dash lights that are dim. I've hooked up many aftermarket radios but never knew it was a no no to hook up the dimmer/illumination orange wires in a '01 civic. I googled it and seen many others with similar issues like mine but nothing exactly like the issue I have.

All the dash lights work, they are dim though. The radio lights work but they are even more dim than the rest of the dash lights. I have check every single fuse under the dash and in the engine bay. The dim controller does not work at all now. I'm guessing that's the issue and from what I read, the dimmers circuit board is in the instrument cluster. Some can fix it, others can't.


I will probably end up buying a used instrument cluster off of ebay, they are not expensive. Hopefully that fixes it since everything else works.


Oh, yes, the brake lights work.


Ted, I think you answered the wrong question...I mentioned nothing about the battery or the low/hi beams

Check the dimmer switch to your dash light. If there turned down, your dash and radio illumination light will be dime or not working at all. Keep me posted, be glad to know if it is the dimmer switch turned down or you dimmer switch has gone bad. Good luck

Check that your tailights/parking lights are working (not the headlights) as this fuse and relay feeds all the instument lights too.... Fuse 15amp TAIL & Tailight Relay

If not then check:
The rheostat (also known as the dimmer switch) may be faulty
as it controls all the illumination of all the backlight bulbs and other dimable switches/indicators.

In general bulbs all together draw a fair amount of current so it is possible that the wiring or ground at the major supply junction feeders has failed but that is a less common problem.

So check the rheostat dimmer wiring area first as all illumination power goes through it.

There is further simple testing we can do with the three wires at the rheostat you can check the entire illumination system.
If you jumper the white/blk to the white/blk all the illumination lights should come on (that means the rheostat is bad).

Or use a voltmeter and measure the green rehostat wire to ground it should be 12volts (if not time to check the fuse, relay and wiring)

If not then finally declare the instrument panel faulty (like burned up circuit board trace).

Note of interest: the rheostat also controls (dims) other switches not associated with the instrument cluster such as the cigarette lighter bulb and hazard switch and radio player and A/C control switch. So if those are dimming but not the instrument panel backlights then yes the instrument cluster needs fixing or a very close wiring inspection.

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.

I had intermittent instrument light problem that went dark for months, until today. :o) I read somewhere that it could be the dimmer switch and didn't think that was my problem as the dimmer worked (dimmed the radio and transmission indicator light) and playing with it never seemed to help with the problem. I did find it odd that dimmer was not completely linear, as it would get brighter up to a certain point and get slightly dimmer with the last little bit of travel.

Today, I took the instrument cluster apart to fix a broken clock, sticking gas & voltage gauges, and to explore the instrument light problem. I took apart the dimmer switch, and to my surprise (was expecting a simple POT), it was a very complicated PCB with some IC's, resistors, transistors, etc. I thought, "all this just to dim the light???" Anyway, I found the POT (potentiometer) and gave a few squirts of WD-40 and found it turning smoother. After putting it back together, the instrument light came back and the dimmer is now perfectly linear. Apparently, less than perfect POT causes some sort of funny logic through the network of IC's and transistors and can cause the instrument light to go on or off randomly at certain intervals.

Anyway, I'm so happy to have the light back along with a working clock and not having to punch the instrument cluster to see how much fuel I have. Not really a posting type, but wanted to help someone else out there with a similar problem with same cause.

1989 740 Turbo