Help - Tacho light went out !
Thread Starter
7th Gear
Joined: Dec 2005
Posts: 7
Likes: 0
From: Perth Western Australia
Help - Tacho light went out !
Hello all...
Encountered my first problem with the 78,
While I was driving at night the tacho back light just went out, (its a pain to drive when you cant see the RPM's) and when I indicate right the green arrow does not flash. All the other lights work fine on the instrument panel and on the outside of the car. How do you change the light globe in the instrument cluster if it has blown ? Perhaps a lose wire or connection ?
Anyone else have this happen to them ?
Appreciate any suggestions as to what to check first ?
Thanks.
Ciao Giuseppe.
Encountered my first problem with the 78,
While I was driving at night the tacho back light just went out, (its a pain to drive when you cant see the RPM's) and when I indicate right the green arrow does not flash. All the other lights work fine on the instrument panel and on the outside of the car. How do you change the light globe in the instrument cluster if it has blown ? Perhaps a lose wire or connection ?
Anyone else have this happen to them ?
Appreciate any suggestions as to what to check first ?
Thanks.
Ciao Giuseppe.
Drifting
Joined: May 2003
Posts: 1,634
Likes: 2
From: Melbourne, Victoria, Australia, the World
Hey Giuseppe,
Sounds like the earth for the tach has gone missing.That's why none of the bulbs work. Means looking behind the instruments for a loose ground wire.
By the look of it the car has not been converted to RHD so at least it may easier to fix than one with a conversion.
How about reducing the size of the pic in your sig so it doesn't take all day to load?
Regards,
Sounds like the earth for the tach has gone missing.That's why none of the bulbs work. Means looking behind the instruments for a loose ground wire.
By the look of it the car has not been converted to RHD so at least it may easier to fix than one with a conversion.
How about reducing the size of the pic in your sig so it doesn't take all day to load?
Regards,
Thread Starter
7th Gear
Joined: Dec 2005
Posts: 7
Likes: 0
From: Perth Western Australia
Well i took the glass off and the tach out, to look at the 4 globes behind the tach, they dont seem to be blown.
The two bottom ones on the spedo dont light up either, only the top two.
Boy its hard to look at where the wires go behind the dash, there is just no room to look ?
The two bottom ones on the spedo dont light up either, only the top two.
Boy its hard to look at where the wires go behind the dash, there is just no room to look ?
Pro
Joined: Oct 2005
Posts: 581
Likes: 0
From: Boynton Beach Florida
to change the bulbs you have to get to the back of the cluster..remove all the screws then disconnect the speedometer cable from the cruise control on the left fender. then you will be able to get the cluster out far enough to change the bulbs ..one more thing you will have to lower the steering wheel for it to clear
Drifting
Joined: Sep 2004
Posts: 1,532
Likes: 4
From: Fairview Heights Illinois, near Saint Louis MO, STL C3 Shark
Yep, real PITA. All of my dash lites were blown when I bought my 76. About a month into owning it I got tired of it and took out the entire dash panel (left, center and right before I knew I could only take out the one I was working on). I ended up replacing the light bulbs and is working fine. now just need to get the tack to stop bouncing.
Racer
Joined: Jul 2005
Posts: 499
Likes: 1
From: Winnipeg Manitoba
Correct me if Im wrong, I'm guessing here...
Doesn't the 78 have newer dash with the flexible circuit board that runs to all the lamps? The fact that you lost half the lamps all at the same time may indicate that one of those flexible traces went open. If you lost the ground, would you lose all the lamps and the tach?
Doesn't the 78 have newer dash with the flexible circuit board that runs to all the lamps? The fact that you lost half the lamps all at the same time may indicate that one of those flexible traces went open. If you lost the ground, would you lose all the lamps and the tach?
Thread Starter
7th Gear
Joined: Dec 2005
Posts: 7
Likes: 0
From: Perth Western Australia
Update ...
Ok guys ... I took the 78 out last night for the first time with the t-tops off, cruised past the beach with my buddy, woo did we attract some attention
Anyways, I know the globs are defiantly not blown behind the tacho, I went over a bump in the road, and they came on and worked for about a minute, then disappeared again. ?
The Right indicator green light will still not flash
My car is a 4 speed by the way, so no cruise control.
However I guess its still the same process of disconnecting the Speedo cable to pull the whole instrument panel out, perhaps its something to do with the flexible circuit board ?
I wonder how much this is going to cost to fix ?
HAHA ... one can only laugh, and whip out the credit card with these muscle cars !
Ok guys ... I took the 78 out last night for the first time with the t-tops off, cruised past the beach with my buddy, woo did we attract some attention
Anyways, I know the globs are defiantly not blown behind the tacho, I went over a bump in the road, and they came on and worked for about a minute, then disappeared again. ?
The Right indicator green light will still not flash
My car is a 4 speed by the way, so no cruise control.
However I guess its still the same process of disconnecting the Speedo cable to pull the whole instrument panel out, perhaps its something to do with the flexible circuit board ?
I wonder how much this is going to cost to fix ?
HAHA ... one can only laugh, and whip out the credit card with these muscle cars !
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Advanced
Joined: Mar 2006
Posts: 76
Likes: 0
From: burlington wi
tach fixes
the bulbs are easy to find & replace behind each gage, which pull out from the front after the lense is removed, it sounds as though the circuit board on the backside of the cluster housing is broke, fractured or has been somehow disturbed. Pretty easy replace. The cause for a jumpy tach needle is usually the seperate small circuit board, directly on the back of the tach unit itself. It's either the tach board or the dampning oil in the needle mechanism has dried up or leaked. Contact a Guy by the name of John Gardner @ 610-797-4048 for help or jt&judyg@aol.com, this Guy is great, he sells a pre-calibrated tach board that is drop in perfect, he can also trouble shoot most probs and offer solutions over the phone. By the way I also have a 78 and have gone through all or most of these probs and John fixed me up GREAT.
Melting Slicks
Joined: Jul 2005
Posts: 2,545
Likes: 3
From: 406ci SB, AFR 180 Heads - 490 HP @5,600 RPM 529 lb-ft @ 4,100 RPM
Originally Posted by Corvette78
HAHA ... one can only laugh, and whip out the credit card with these muscle cars !
Friend Request Magnet
Joined: Dec 2005
Posts: 50,242
Likes: 149
From: ♫ ♪ ♫♫ ♪ ♫ ♪♪ ♫
Before You Whip Out The CC
Check all your bulbs on the exterior side markers that work with the headlights/turning indicators.
Mine does the same thing...I go push the right-front side-marker bulb back into place and ....VIOLA! all is good again.
Every month or so the bulb loosens in its socket and needs to be pushed in.
That indicator light staying on and not flashing is a sign that there is a break in the circuit.
If not there...check the indicator bulb and socket behind the dash.
Unscrew, clean and check all your bulbs and corrosponding sockets before you deem the P/C board bad and purchase a new one.
On these old cars; the "bulb and socket check" is preventative maintenance...lol
BTW--this is a "free fix".
Jim
Mine does the same thing...I go push the right-front side-marker bulb back into place and ....VIOLA! all is good again.
Every month or so the bulb loosens in its socket and needs to be pushed in.
That indicator light staying on and not flashing is a sign that there is a break in the circuit.
If not there...check the indicator bulb and socket behind the dash.
Unscrew, clean and check all your bulbs and corrosponding sockets before you deem the P/C board bad and purchase a new one.
On these old cars; the "bulb and socket check" is preventative maintenance...lol
BTW--this is a "free fix".
Jim
