PLEASE HELP! Dashboard backlighting issue-It's not a fuse!

[d2_mcgill]

Hello,

I have a CX 7, last month I needed to change a light bulb in the center console (the bulb for the fan speed control). After fitting the new bulb it was flickering (bad contact) so I stupidly stuck the screwdriver in to tighten it while the lights were still turned on and I shorted something out, you could smell the electrical smoke, but I couldn't see where it came from . All that happened was the screwdriver bridged the terminals for the light bulb that lights up the fan speed knob, but the result is driving me insane, please help... I've been pulling the car apart for a month now!!

The result is (when the headlights are on) all the lights for the steering wheel, HVAC controls, radio, info screen and the little blue light up in the headliner that lights up the gear shift area are out completely. Yet the gauge cluster (speedo, RPM etc.) still works perfectly, including the dimming knob!?!?!?!?

If press the dimmer control then the info screen comes on full brightness, as does the gauge cluster, but all the other lights stay off.

So the speedometer gauge cluster works normally, but all the light on the centre console and steering wheel are out.

I took it to Mazda and nothing came up using there scan tool, but they said they think it's the Body Control Module (BCM)... I replaced the BCM at a large cost and the problem is still there.

I have checked ALL the fuses (every fuse in the car) repeatedly, I have checked all the wiring and all the grounds... I can not see what has burned out/shorted out!! Has anyone seen this issue before? Does anyone have a better understanding of the wiring schematics and might be able to tell me what may have shorted??

Please help!

 

[Skyhessen]

The expensive Body Controle Module (BCM) replaced, but it still doesn't work?
Have you checked all the bulbs?
It might be possible that a small bulb has broken somewhere (indicator lights, glove compartment lighting, cigarette lighter lights etc.)

If 1-2 of these lamps are broken, the lighting control system likes to have its own life.

 

[d2_mcgill]

The expensive Body Controle Module (BCM) replaced, but it still doesn't work?
Have you checked all the bulbs?
It might be possible that a small bulb has broken somewhere (indicator lights, glove compartment lighting, cigarette lighter lights etc.)

If 1-2 of these lamps are broken, the lighting control system likes to have its own life.

I think the only bulb that is out is the RHS reverse light, but I have a new one arriving tomorrow so I will replace it.

I've disassembled the entire dash twice, the second time I had an electrician with me. I have opened up every electrical unit including the light unit-auto, HVAC switch control, info display, and the main instrument cluster (to check the dimmer switch)....I've inspected for blown or shorted capacitors and/or relays... I smelled every circuit board, but nothing! I've replaced every fues in the car....I've even taken the car to Mazda, they found no fault codes and couldn't find the cause, so they suggested replacing the BCM and that hasn't worked... Now they want to just start replacing all the electronic modules one by until the fault goes away, but I can't afford that.

A few things that would really help me:
-Does anyone know if the center console and steering wheel backlights have there own separate dimming circuit?... They appear to run independently to the speedometer/RPM cluster backlights.

- Does anyone know what wire or pin number is for backlighting on the radio, HVAC control and info screen?

-Does anyone have, or know where I can get a wiring diagram for the backlighting?

Any information or help would be incredible appreciated!

Dave

 

[Skyhessen]

Did you also check the bulb in the glove box? Mostly this one is the reason of a lot of mistakes ...

Couldn't they use and test individual modules in the garages on a trial basis? Why should you pay for all this? And if at all, could only the Mazda garage itself organize an electrical circuit diagram?

 

[d2_mcgill]

Did you also check the bulb in the glove box? Mostly this one is the reason of a lot of mistakes ...

Couldn't they use and test individual modules in the garages on a trial basis? Why should you pay for all this? And if at all, could only the Mazda garage itself organize an electrical circuit diagram?

Yes, the glove box light is good, but I still changed the bulb for a new one... I have changed every possible bulb.

To be fair to the dealer they didn't have much time to investigate, it was just before Christmas. They just plugged in there diagnostic computer and said there were no codes and everything seemed ok, so the next most likely area would be the BCM.

Last night it occured to me the only place I have not looked is the light control switch next to the steering wheel (the one for turning the headlights on)... I will check that tonight.

 

[Skyhessen]

This is typical for a trader - earning money quickly by selling, but not having time to do well in case of technical problems.
That's all I can think of right now to help you. Maybe another user is able to help with another hint?