Hey guys,
I have an `87 GN with a zillion miles on the clock. Why might it be that whenever I turn on my parking lights (or just my headlights, for that matter) that the factory boost gauge and tachometer led's go out/off? Turn my lights off, and the led's come back on. What's going on here? All the running lights & headlights work fine on the outside of the car.
Is your interior light dimmer switch all the way down?
Nope... it's all the way up. I moved it all around, as a matter of fact. Doesn't seem to make a difference.
I have the same, exact problem! I hope we get this one solved. Because I am at wits end solving this one.
Do the cluster lights dim with the dimmer?
Hey Shawn... you have posed a good question. I generally only drive this car from dawn to dusk and can't really tell if the cluster lights are dimming or not. Which is to say, I never drive it when it's dark enough out to even have the headlights on! I just like having my running lights on because it's supposed to increase other driver's awareness of my being there and not to mention it looks cool.
The few times I drove this car at full-on night, I remember the cluster lights being VERY dim, (compared to other car brands I have) even with the dimmer switch set at the brightest position. I'll check tonight, though!
Okay... I have just come in from checking my cluster lights. (like I said, I rarely seem to drive this car at night) And get this: the cluster lights don't even work! I KNOW they were working a few weeks ago when I had the car out kinda' late. Which, by the way, that very evening I got in one helluva' great race with a fully hot rodded ricer! (a turbocharged Acura) My first ever with one of these clowns. I got him in the mid range and pulled a car and a half open on him, but around 90mph we leveled off and I couldn't put any more space on him. We were racing on to a freeway, so don't think we were doing this on a service road. But I digress... so do I maybe just have a blown fuse since the cluster lights don't work?
Well, I was in the car earlier today and I flipped on the running lights only to watch the tach and boost led's go out. (no surprise) But about 5 hours later I decided to hop in, cruise on Woodward Ave for a couple laps then hit the video store only to watch the led's mysteriously spring back to life! What the hey?? Loose connection somewhere I guess?
Yup, as I stated before, I have the same, exact problem! I hope we get this one solved because I am at wits end solving this one. I do not drive me car much either, and the problem was intermitting. Now it is all the time.
How about going to the junk yard and getting a new dimmer switch? Light switch to, maybe.
you have a blown fuse.check your cigarret lighter circuit it may have a short.the same thing happend to me.not to long ago.
Is there a solution to this problem? I have checked all my fuses, changed the headlight switch unit. Now I am going to put my old switch in car that I swapped switches to see if my old switch will work in it.
If anyone have an Idea, please post.
Thanks
A few words about how the Boost/Tach guage works and possible further troubleshooting may be of help if you haven't fixed the problem already. The boost/tach guage has an electronic circuit driven by two wires (Gray and Brown at the guage) that dims the LED display when the park or headlights are turned on. The Gray wire comes from the headlight switch and has a constant 12 volts (12v) on it when the park or headlights are on, 0 volts (0v) when they are off. The headlight switch also supplies 12v to the dimmer control which in turn goes to the Instrument Panel fuse. This fuse then feeds all the lights that are dimmed and also connects to the Brown wire going into the boost/tach guage. With the lights on, the voltage on the Brown wire is about 12v with the dimmer set to maximum brightness and decreases to 0v with the dimmer all the way down. The circuit in the guage works off of the difference between the voltages at the Gray and Brown wires going into the guage. When the voltage to both wires is 0v (headlights off), the LEDs are at maximum brightness. With the headlights on and the dimmer at maximum brightness, 12v is present at both wires and the LEDs are partially dimmed. As the dash lights are dimmed, the voltage going below 12v at the Brown wire causes the electronic circuit to further dim the LEDs, turning them off when the voltage reaches 0v.
Bottom line, if the dimmer control is open, the instrument panel fuse blown, the Brown wire is broken, or the guage wiring connector pin for the Brown wire is bad, there will be no voltage at the Brown wire input to the guage (as if the dimmer were turned all the way down) and the LEDs will go dark when the park or headlights are turned on. If you have a volt meter, check the voltage at the Gray and Brown wires on the guage connector (not easy to get to as it is up under the dash to the right of the steering column). If the voltages act like described above, the guage is bad.
Hope this wasn't too long and clearer than mud. If so, it may help you find your problem and fix it.
Mel Phillips
Philtronix, Inc.
mplists@bellsouth.net
Boost/Tach guage repairs and upgrades
87 GN, 123k mostly stock, rebuilt engine at 106k due to @#$% nylon cam gear
69 427 Tri-Power Vette basket case long term restoration
94 S-10 Blazer daily grocery getter
which fuse is it, in the panel.
my cluster just went out today when i put the car in reverse.
the wire connections in my b&m street stick toched the shifter and shorted the cluster and the trans indicater.
one more problem. where do the reverse light switch wires wires connect to the harness.
the owner b4 me dissconnected them for some strange reason.
Humm - when I turn on the headlights the dash lights go out, my aftermarket instruments still work but no dash. Then, sometimes when I go through wet conditions, my tach and boost light up momentarily. Checked the fuses, changed same (5a I think), soons I hit the brake, fuse blows.
Been this way for 3 years - since I had some work done with the linkage....
You may want to check in the console - the light that shows the gear position often has the wires in the socket break off and short against the shifter linkage. Pull the top plate, undo the two s/m screws holding in the plastic square hole thing, remove the shifter plastic thing that slides (pardon the technical lingo), and you'll be able to access the shifter light socket. Twist and remove. If it is broken off, it can be fixed - drop me a note if you want to fix it.