So I've had this issue for a long time, and I'm going to give the online world one more chance at trying to figure out what it is.

I have a problem where all my dash and HVAC lights flicker when my headlight switch is off. If I switch in reverse, the flickering stops, but it resumes when I shift out of it.

I'll try and get some new videos tomorrow, but this video shows the same thing:

http://www.youtube.com/watch?v=Sb30d7AXY7s

Any Ideas?

 

m/t???, hmmmm....

 

Auto

 

have you had your console, and shift assembly disassembled yet??...if not, do that, and look for a bare wire somewhere, anywhere between there and your ecu, sounds like you are grounding out somwhere...sorry so vague, bu this issue doesnt indicate a clear concise cause.

 

I'll check it out! I'll keep ya posted

 

is this an 07 tC? they have a known problem with the hvac circuit board.

edit: just saw the video.. um.. wow. it's not just the hvac controls but everything. do the headlights do this too?

 

The headlights do not do this. I'm wondering if it's because my shifter and cubby light are out. I'll find out in 20 days when the lights arrive from China.

 

well i'll take a look at the wiring diagram later and let ya know what is on the same circuit as the speedometer and hvac, that would cause that.

 

Awesome man, thanks a bunch!

 

no problem.. Ok, I've been looking at the wiring diagrams between the instrument panel, auto shift indicator switch, and the headlights. I see that the headlights aren't that involved in the circuit but the shifter indicator and instrument panel definitely are.

Okay so between all three the power source they share goes through three sources, the IG fuse which is a 10amp fuse. The location is the fuse panel under the dash on the driver's side. The 10A MET IG2 fuse, also in the same location but the last one involved is the 10A ECU-B fuse located in the left side of the engine bay.


Here's this is better
HVAC Controls = 10A GAUGE IG + 10A ECU-B
Shifter = 10A GAUGE IG
Combination Meter (speedometer etc) = 10A MET IG2 + 10A ECU-B

But as I'm looking at this, the combination meter continues to be the source in common among all these since the power is shared between the HVAC controls and the combination meter. The shifter hooks up to the combination meter to tell you what gear you're in. When you go into reverse it looks like the signal is then split between the combination meter and the engine control module (ECM). That split might reduce the voltage to the combination meter when you shift into reverse stabilizing the voltage short, removing that flicker. Now this big question is this. If you're in Park do the lights on the shifter flicker too? Or just the HVAC and Combination meter? If they don't, my money is on the 10A ECU-B fuse. But please check all these and see what condition they're in.


one other thing, the headlight switch does go through the combination meter, and when it's off, there is no voltage flowing through the combination meter from the headlight switch, only when the headlight switch is turned on is the combination meter involved. Makes me think the combo meter is the problem here.

Okay keep us posted.

saga continues...

 

Sounds like a intermittent ground! Install/Un-install anything lately? I would pull apart the waterfall and shifter area and look for a loose wire or bare wire. Check all connections in that area as well as they may be loose. We get alot of this happening from the vibrations and wave action on the boats.

 

I'll check it out! I didn't see any loose wires when I took some unused wires out a few days ago. I'll check again though!

 

^^ had to update my post for more details, take another read thanks

also just checked the diagrams, and yep, both the combo meter and the hvac controls share the same ground! i'm looking now to find where it is.

 

When I do shift into reverse it does stop the flicker.

 

okay well here's some more info, the locations of the grounding points that control both HVAC and the instrument panel (combination meter)
Location : "Front Left Side of the Cylinder Head" which as you look at the engine is on your right (driver's side) as you look when standing in front of engine bay.

Separate ground points (not in common, but exist for each)
Combination meter = passenger front fender
HVAC = drivers front fender

 

yes i figured that out, the signal splits from the combination meter and the ECM, it's in my post up there ^^

 

I'll check the fuses and ground points tomorrow an get back to you!

 

Ok, so I checked the fuses, and they were all intact. With respect to the grounding points, do you have pictures of them? My grounding points might not be there due to modifications, which is what I'm worried about.

Thanks,
Michael

 

PM'd you.

 

Everyone!

I have excellent news! After over a year, I have found the solution, and it's sadly very simple.

It turns out it was because the bulbs were dead in the cubbyhole and shifter. When I replaced just the cubbyhole light, the problem was solved.

Thank you guys so much for all your help, and I'm so glad this saga is over!