Question about Cobra 29 WX NW ST 40-Channels Base CB Radio

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No front panel lighting

The dimmer works properly in adjusting the lighting of the channel display and signal meter. But the front panel does not light up. Is this a simple fix such as a bulb replacement?

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  • oldcars Nov 25, 2007

    The nightwatch feature worked on my cobra 29 until I had a shop replace the blown meter light with one of the multicolored rainbow lights. Now the backlight for the knobs doesn't light. The l.e.d. lights are fine.

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1 Answer

The "nightwatch" lighting uses an EL or electroluminescent material that does degrade with age. If the radio is old, then it may be lighting very dimly (check in a dark room with the dimmer at full bright). The material is connected by a ribbon to a special high voltage pulsed powersupply that runs at about 500 volt. If the power supply is working then a new face would be in order or a new radio. If the powersupply is not working it may be repairable but requires working with surface mount components. Either way, it is NOT a simple lightbulb fix. I have successfully repaired and do stock the smc components to repair but cannot get the faces through cobra ($$$). More info? Contact through www.cbshop.info

Posted on Feb 22, 2007

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2005 cavalier dash lights not working. all fuses are goood. replaced cluster, dimmer switch, multifunction switch


Back lighting or warning lights ? check engine , ABS , air bags , seat belt , oil light etc... ?
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.
• Power window switches
• HVAC control head assembly
• Radio
• The instrument panel cluster (IPC)
When the ignition switch is turned to the ON position, the vacuum fluorescent (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 IP dimmer switch. At the same time all vacuum fluorescent (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 instrument panel dimmer switch through the instrument panel dimming lamps control circuit. The setting of the instrument panel dimmer switch determines the amount of voltage that the instrument panel dimmer switch supplies to the BCM through the instrument panel dimming lamps low reference circuit. The BCM then sends a pulse width modulated (PWM) voltage to all the interior lamps. All the vacuum florescent (VF) and incandescent back lighting lamps are provided a specific voltage and are then grounded. When the headlight switch is turned to the PARK or HEADLAMP position, all incandescent back lighting turn on at the dimming level indicated by the IP dimmer switch. When the IP dimmer switch is moved from MIN to MAX, all vacuum fluorescent (VF) displays, as well as all incandescent back lighting respond from Minimum intensity to maximum brightness in response to the IP dimmer switch.

I would have it checked for DTC'S - diagnostic trouble codes stored in the BCM !
DTC B2624 Display Dimming Input Range/Performance
The body control module (BCM) supplies voltage to the instrument panel dimmer switch through the instrument panel dimmer switch signal circuit. The dimmer switch varies the voltage and returns the new voltage to the BCM through the dimmer switch signal return circuit. The BCM uses this voltage to determine the illumination level of the instrument panel lamps.

DTC B2625 Display Dimming Pulse Width Modulation (PWM) Output Circuit Range/Performance
The body control module (BCM) receives a variable voltage from the instrument panel (I/P) lamp dimmer switch. The BCM uses this signal in order to vary the illumination level of the I/P lamps. The I/P dimming lamps output from the BCM is a pulse width modulated voltage supply used to light the I/P lamps. If a malfunction occurs in the I/P dimming lamps output circuit, this DTC is set.

DTC B2662 Park Lamp Switch Circuit Malfunction
The park lamps are controlled by the turn/headlamp switch. Positive battery voltage is supplied to the switch through the EXT LP fuse. When the turn/headlamp switch is placed in the park or head position, battery voltage is supplied to the park lamps. The body control module (BCM) is also connected to the park lamp circuit to sense whether or not the park lamps turn ON when the low beam or high beam headlamps are turned ON. The BCM also uses the parklamp battery positive voltage to power the instrument panel (I/P) dimmer output circuit. If the BCM senses that the low beam or high beam headlamps are ON and the park lamp input is not active, DTC B2662 sets.
Do the park lamps work ?

Jun 11, 2017 | Cars & Trucks

1 Answer

My front panel display is not working.


check to make sure you don't have the dimmer down too low. you can adjust this option to make the room darker if the front panel is distracting while watching a movie etc.

Mar 14, 2014 | Yamaha RX-V530 Receiver

1 Answer

Instrument Panel Lights


Daytime headlight issue ? No , no sensor behind the front bumper . No Daytime time head lamp issue , doesn't turn on the instrument panel light's . This is more then likely a remote dimmer module problem .
Interior Lights Dimming Circuit Description (Pontiac)
When the park lights are on, battery positive voltage (B+) is applied via CKT 32 (YEL) to the remote dimmer module. The interior dimming switch in the lamp dimmer switch is a variable resistor which applies the dimming input via CKT 44 (DK GRN) to the remote dimmer module. The potentiometer in the lamp dimmer switch cannot provide enough current in order to operate the incandescent lights. The remote dimmer module amplifies the current, applying a variable voltage to the incandescent lights. As the amount of current increases, the lamps become brighter. As the amount of current decreases, the lamps become dimmer.
The radio, heater and A/C control assembly, instrument cluster, and passenger climate control each has a vacuum fluorescent (VF) display. When each module receives an input that the ignition switch is turned to the RUN position, each module activates the VF display at the full intensity. When the park lights are on, the radio receives the dimming level from an input on CKT 8 (GRY). The radio then relays this information to any other modules with VF displays. All modules with VF displays then adjust the dimming level of their VF display in order to match the level of the incandescent lamps.

May 16, 2017 | 1998 Pontiac Bonneville

1 Answer

I have a 2004 Saturn Ion 2. I have several random problems with the car. First the Coolant light always come on when I first start the car, there is coolant in with no leaks. The Coolant warning does not...


Could have connection issues at the BCM - body control module , lose ground . The BCM controls all the thing's your have problems with .
Turn Signal Lamps
When the turn signal switch is place in either the right or left turn position, the turn/hazard request circuit is pulled low, through a resistor. The body control module (BCM) uses the resistors to determine if the left or right turn signals have been requested. The BCM then supplies an ON-OFF voltage to the turn signal lamps and turn signal indicator on the selected side of the vehicle. The turn signals receive a ground at G101, G401, or G403.

When the ignition switch is turned to the ON position, the vacuum fluorescent (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 IP dimmer switch. At the same time all vacuum fluorescent (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 instrument panel dimmer switch through the instrument panel dimming lamps control circuit. The setting of the instrument panel dimmer switch determines the amount of voltage that the instrument panel dimmer switch supplies to the BCM through the instrument panel dimming lamps low reference circuit. The BCM then sends a pulse width modulated (PWM) voltage to all the interior lamps. All the vacuum florescent (VF) and incandescent back lighting lamps are provided a specific voltage and are then grounded. When the headlight switch is turned to the PARK or HEADLAMP position, all incandescent back lighting turn on at the dimming level indicated by the IP dimmer switch. When the IP dimmer switch is moved from MIN to MAX, all vacuum fluorescent (VF) displays, as well as all incandescent back lighting respond from Minimum intensity to maximum brightness in response to the IP dimmer switch.

Engine Coolant Indicator(s)
LOW COOLANT LEVEL
The IPC illuminates the low coolant warning indicator when any of the following occur:
• The BCM detects a low coolant level condition for at least 30 seconds. The IPC receives a class 2 message from the BCM requesting illumination.
• The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds .

The thing to do first would be to hook up a factory or professional type scan tool an check for Instrument cluster or BCM DTC'S - diagnostic trouble codes . Then checking connection 's at the BCM , testing power an grounds .


ECM Inputs and Outputs Diagnosis

Open Circuit Detection Wiring Diagram 1

Mar 28, 2017 | 2003 Saturn ION

1 Answer

Cobra cb radio backlight inoperable


look inside at meter--two wire bulb with rubber boot slides at a angle into the meter and is easy to replace.

Apr 06, 2012 | Cobra 29 WX NW ST 40-Channels Base CB...

1 Answer

D4dmx-md5 stop working. No schematic. Problem came slowly then it stop working. Get a bit of light on the led display Maybe a power supply problem


You did not post enough information on symptoms to get a good answer. However, the most common problem with these dimmer packs is a failure of the sermiconductor that controls the amount of power going out to the attached light. In the D4DMX, there are 4 such, of a type class of semiconductors known as "triac", part industry part BT16A (the "A" is important, as it indicates an internally insulated mounting/heatsink tab). When this part fails, the output channel stops working, but the other 3 channels continue to work. Altho rarer, it is possible for multiple channel triacs to fail. The failure of a triac is typically due to (1) attached bulb filament failure (in a manner where a filament fragment shorts across the mounting posts), (2) channel overload (eg, plugging in a greater load (significantly greater wattage) than the D4DMX channel is rated for), (3) AC power line surge. You need to be a trained & experienced ELECTRONICS (ie, NOT electrician) to accomplish this repair safely & satisfactorily, and it involves soldering & specialized test equipment.
The D4DMX series is also known for failures of its control cable interface circuitry, both for Microplex and DMX. Microplex failures is more common, as that type of interface is more sensitive to induced noise from nearby AC wiring, radio signals, and standing wave reflections from varying lengths of control cabling. DMX uses a differential control signal interface, which makes it much more immune to induced noise, but it operates at a lower signal voltage which makes it more sensitive to accidental application of improper voltages on the control cable...which often happens when someone connects the DMX ports on the dimmer pack to a Microplex connector on another pack or the control console. One clue is to look at the single tiny LED right next to the control cable connectors; if it's lit green, then the Microplex signal is detected, if it's lit red the DMX signal is detected, if it's not lit at all (off) then no signal is detected which just may be an interface circuit failure. Such problems are a bit more challenging to troubleshoot internally, and requires a proper oscilloscope or logic analyzer.
In both of the above cases, you will see what may look normal on the LED display, but the dimmer pack will not function properly.
You should describe more symptoms of your problem, such as: Are all light output channels not working, or just 1 or 2? Which control interface are your using (Microplex or DMX)? What is your LED display saying? What are the present settings programmed into your D4DMX? Are any other working channels responding to the control console normally? What is the total length your control cables, including those between serial connected ("daisy-chained") multiple D4DMX dimmer packs? Do you have any non-D4DMX dimmers in the control chain, and are they all connected using the same type of control interface (Microplex or DMX)?

May 23, 2011 | Leviton D4DMX-MD5 4-Channel Programmable...

2 Answers

83 CJ7 head lights, parking lights and turn signals problems.


TRY REPLACEING THE DIMMER SWITCH,THEY CAN CAUSE WIERD THINGS TO HAPPEN.

Oct 02, 2009 | 1983 Jeep CJ7

1 Answer

Lazy signal needle


Probably NOT the potentiometer that assists the meter. I would suspect a abad needle in the meter. I'd see if you can get to the adjuster screw on the meters front. Many times it's hard or impossible to adjust due to the way it's mounted.

Jan 12, 2009 | Midland 4001 40-Channels Base CB Radio

2 Answers

Dim Display


On newer stereos, you might have to experiment with the "panel" wire.

I just installed a VR3, and discovered that the more voltage on the "panel" wire, the dimmer the display.

With no connection, you get full (daytime) brightness. With full voltage, you blank the display.

I wired mine up to the car's instrument lights through a 10Kohm trim resistor so I could adjust the "night" intensity. But if I dim the car's instrument lights, the stereo gets brighter. Oops.

Older car -- I can't just flip a software bit. ;)

But I gather a lot of new stereos are like this. The display on my (factory) stereo in the Mitsu dims a fixed amount when the lights come on, but doesn't adjust with the car's instrument dimmer.

Sep 23, 2007 | Car Audio & Video

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