Paging Willcox - tach issue
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Race Director
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
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Paging Willcox - tach issue
A while back you sent me some instructions on tach troubleshooting. I have a new PC board from you and I installed a new tach filter. Your advice was to run a lead from the alternator to the pos post, engine ground to the ground post, and direct off of the distributor tach lead to the input post.
Here's my dilemma. The posts aren't marked. I've attached a photo. Can you tell me which lead is which. I know only three of these are used. Thanks.
Here's my dilemma. The posts aren't marked. I've attached a photo. Can you tell me which lead is which. I know only three of these are used. Thanks.
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
This may help till Willcox arrives
http://willcoxcorvette.com/product_i...ducts_id=26762
http://willcoxcorvette.com/product_i...ducts_id=27058
http://willcoxcorvette.com/product_i...ducts_id=26286
http://willcoxcorvette.com/product_i...ducts_id=26762
http://willcoxcorvette.com/product_i...ducts_id=27058
http://willcoxcorvette.com/product_i...ducts_id=26286
Last edited by '75; Sep 23, 2011 at 07:53 PM.
Thread Starter
Race Director
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
2022 Corvette of the Year Finalist -- Modified
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Thanks. The second link will get me on the right path.
Former Vendor
Joined: Aug 2006
Posts: 76,656
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
I knew someday.. these links on my site would pay off...
let me know if you have any issues..
On a funny note.. we just learned today that with a different calibration... the tach board with some mods will also fit 1973-1986 Chevy and GMC truck.. who woulda thunk it.....
So I suppose we are not in the truck tach board business...
let me know if you have any issues..
On a funny note.. we just learned today that with a different calibration... the tach board with some mods will also fit 1973-1986 Chevy and GMC truck.. who woulda thunk it.....
So I suppose we are not in the truck tach board business...
Former Vendor
Joined: Aug 2006
Posts: 76,656
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Voltage on the board is always the highest terminal... Input signal is always the lowest.. this is the best way I know of to keep track of it.
Thread Starter
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
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OK. I just checked it by the method Willcox suggested. Here's what I have:
With the tach out of the car and hard wired, the needle drops to below zero as far as it can physically travel.
If I move the needle manually while still hard wired it jumps past 7000 to where it can't physically move.
I did not start the car while hard wired.
When I check voltage at the speedo/tach cluster where the tach snaps in, I'm only getting 6V.
What's next? Thanks for the help everyone.
With the tach out of the car and hard wired, the needle drops to below zero as far as it can physically travel.
If I move the needle manually while still hard wired it jumps past 7000 to where it can't physically move.
I did not start the car while hard wired.
When I check voltage at the speedo/tach cluster where the tach snaps in, I'm only getting 6V.
What's next? Thanks for the help everyone.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Something is wrong.. you should have 12 volts aprox. at the clip.
Did you do a zero set after you installed the board? The needle should go to zero when you power it up
If hard wired with power and ground all the needle should do is go to zero. Then you add the signal wire from the distributor with the car running and you will get a idle reading. Rev the engine up and your needle should move upward with it.
Willcox
Did you do a zero set after you installed the board? The needle should go to zero when you power it up
If hard wired with power and ground all the needle should do is go to zero. Then you add the signal wire from the distributor with the car running and you will get a idle reading. Rev the engine up and your needle should move upward with it.
Willcox
Thread Starter
Race Director
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
2022 Corvette of the Year Finalist -- Modified
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Something is wrong.. you should have 12 volts aprox. at the clip.
Did you do a zero set after you installed the board? The needle should go to zero when you power it up
If hard wired with power and ground all the needle should do is go to zero. Then you add the signal wire from the distributor with the car running and you will get a idle reading. Rev the engine up and your needle should move upward with it.
Willcox
Did you do a zero set after you installed the board? The needle should go to zero when you power it up
If hard wired with power and ground all the needle should do is go to zero. Then you add the signal wire from the distributor with the car running and you will get a idle reading. Rev the engine up and your needle should move upward with it.
Willcox
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Former Vendor
Joined: Aug 2006
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
I just bumped the video thread.. but here is the link.. it will take you from start to finish on how to install the board!
http://forums.corvetteforum.com/c3-t...78-1982-a.html
http://forums.corvetteforum.com/c3-t...78-1982-a.html
Thread Starter
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
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I just bumped the video thread.. but here is the link.. it will take you from start to finish on how to install the board!
http://forums.corvetteforum.com/c3-t...78-1982-a.html
http://forums.corvetteforum.com/c3-t...78-1982-a.html
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Thanks for the video link. I have good news and bad news. The good news is the tach works correctly once zeroed. The bad news is it only works when hard wired. When I plug it into the dash it stays at 2K. I checked the voltage at the plug ins in the dash and I still get 5V and no more. Is there something I can check without ripping the entire cluster out? Something is loading down the voltage somewhere.
Just as I posted earlier, something has to be wrong for there to be 6 volts on the power clip... Pull the center cluster.. check the printed circuit and test the power wire on the pinch connector and see if you have the same reading there.
Here... the links you'll need:
Corvette Speedometer and Tach Housing Removal Instructions 1978-1982
http://willcoxcorvette.com/repairand...lp.php?hID=146
Willcox
Thread Starter
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
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Thanks. You're a life saver.
Thread Starter
Race Director
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
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Does the steering wheel really need to come off? It looks like there would be enough room once the column was dropped to slide the cluster out. I've already had the wheel off when I repaired the horn so it's no big deal. I'd like to avoid taking it off again if at all possible. I'm not messing with it tonight. My 06 Vette needed some attention (needed detailing). Thanks.
Le Mans Master
Joined: Oct 2005
Posts: 6,247
Likes: 471
From: Glen Allen, VA
No, you can remove the tach/speedo cluster w/o taking the wheel off. I've done it many times on my 79. Of course you tilt the column to the lowest position. If you have a non tilt column, that might be a different story.
Thread Starter
Race Director
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
2022 Corvette of the Year Finalist -- Modified
2021 C6 of the Year Winner - Modified
2020 C7 of the Year Finalist -- Modified
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It's a tilt column. Thanks. I might work on it tonight.
