The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 12-28-2005, 12:46 PM   #1
Gennoy
Registered User
 
Gennoy's Avatar
 
Join Date: Nov 2005
Location: Antelope, CA
Posts: 21
Factory Tach Install

Hey All,

I rebuilt my gauge cluster installing a factory tach. I put the gauge cluster back into the truck and plugged in the tach to my HEI and tried to start my truck. Unfortunately I get no spark with the factory tach plugged in. Once I unplug the factory tach from the HEI the truck fires up just fine. I plugged in an existing Sunpro tach I had into the HEI and had no problems. So it seems the problem is with the new factory tach.

The rest of my gauges all work fine with the exception of the "Battery" gauge where the needle just sits in the center. I know my truck is charging correctly because I get ~14 volts at the battery when the truck is on. But it seems the needle doesn't move. Is that right?

Unfortunately I am not the one who took my truck apart (I bought it in pieces). So I am slowly trying to learn how to put it back together. The only things running to the cluster are the gauge harness plug, the oil pressure line and the tach harness. Is there something that I am missing? Or is it just a bad tach?

Thanks in advance for all the help.
__________________
1969 Chevrolet C-10 SWB
Gennoy is offline   Reply With Quote
Old 12-28-2005, 01:27 PM   #2
72MARIO
Registered User
 
72MARIO's Avatar
 
Join Date: Nov 2000
Location: Huntsville Ontario Canada
Posts: 4,051
Re: Factory Tach Install

My battery gauge does not seem to move either. I have a new battery and alt. I have not seen one of theses gauges move very far mabye 1/16 " if ever. I would not worry about it.
__________________
1968 Suburban numbers matching all original truck now equipped with 6.0/4L80 on Accuair
http://67-72chevytrucks.com/vboard/s...d.php?t=625017
1967 C/20 6.0/4L80 Roofing Truck
1990 V2500 Suburban "Plow Truck"
2005 TAHOE DD
72MARIO is offline   Reply With Quote
Old 12-28-2005, 02:19 PM   #3
Gennoy
Registered User
 
Gennoy's Avatar
 
Join Date: Nov 2005
Location: Antelope, CA
Posts: 21
Re: Factory Tach Install

Thanks, I was just hoping it was something simple like a ground not hooked up or something. I was thinking that the battery gauge may be an indication to the problem with the tach.

Frustrated seeing this beautiful new gauge cluster and having the tach not work.
__________________
1969 Chevrolet C-10 SWB
Gennoy is offline   Reply With Quote
Old 12-28-2005, 02:46 PM   #4
JimKshortstep4x4
Senior Member
 
Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
Re: Factory Tach Install

Make sure that the Tach housing is getting a good ground from the gauge housing and that gauge housing is well grounded.

On the ammeter, make sure both fuses are good, (one on each side of the radiator attached to the harness inside of small football looking rubber fuse holders).

Jim
JimKshortstep4x4 is offline   Reply With Quote
Old 12-28-2005, 02:50 PM   #5
53burb
Senior Member
 
53burb's Avatar
 
Join Date: May 2004
Location: Queen Creek, AZ
Posts: 1,010
Re: Factory Tach Install

As for the amp gauge, there are two fuses on each side of the engine bay, one by the battery and one one on the drivers' side. Those are usually burnt out. I don't have a factory tach, but IIRC, somebody else had this same problem, and I believe some of the other members said the tach is not grounded correctly. They will probably respond later.
53burb is offline   Reply With Quote
Old 12-28-2005, 02:51 PM   #6
Gennoy
Registered User
 
Gennoy's Avatar
 
Join Date: Nov 2005
Location: Antelope, CA
Posts: 21
Re: Factory Tach Install

How is the gauge housing grounded to the car? Is it through the harness, or is should there be a seperate wire grounding it to the chasis?

Unfortunately I live 107 miles away from my truck so I won't get to play around with it until this weekend. I was just hoping to get some ideas of what the problem may be before I get there this weekend.

Thanks
__________________
1969 Chevrolet C-10 SWB

Last edited by Gennoy; 12-28-2005 at 02:51 PM.
Gennoy is offline   Reply With Quote
Old 12-28-2005, 09:04 PM   #7
JimKshortstep4x4
Senior Member
 
Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
Re: Factory Tach Install

Make sure the ground straps are in place from the engine to the firewall.

The gauge housing can be grounded to the metal part of the dash with a short length of black wire, (black is the standard color for ground wires). Using terminals on the wire fasten one end to the housing with one of the 1/4" headed fasteners.The other end is screwed to the metal part of the dash.

Jim
JimKshortstep4x4 is offline   Reply With Quote
Old 12-28-2005, 10:16 PM   #8
Longhorn Man
its all about the +6 inches
 
Longhorn Man's Avatar
 
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,690
Re: Factory Tach Install

There should be a clip on ground strap from the inst panel to the dash....but it is normally missing.
The inst panel should ground OK without it, however, adding a ground is a good idea.

However, i don't think that's your problem. Normally, if there is a ground problem, the fuel guage will act stupid, esp when you turn on the headlights or a turn signal.

The ammeter is probably the fuses like mentioned. With the key on, engine off, turn on your headlights with the hight beams on, the needle should make obviouse movement to the left. If it doesn't move at all, then move on to the fuses.

Your tach is acting like it is wired wrong internally, or on your connections. One terminal is 12 volt input, the other is for the tach wire. It grounds through the frame of the inst panel. if you were to take that wire from the tach terminal on the dist, and ground it when the engine is running, the engine would shut off instantly. It sounds to me like that is what's happening here. Double check your 2 connections, the 12 volt in, should be on a keyed source on the fuse box. The ignition switch unfused is where you'd want to go with the power lead.
Attached Images
 
Longhorn Man is offline   Reply With Quote
Old 12-28-2005, 10:39 PM   #9
Gennoy
Registered User
 
Gennoy's Avatar
 
Join Date: Nov 2005
Location: Antelope, CA
Posts: 21
Re: Factory Tach Install

The kit I received came with a v-shaped plug for the back. I assumed it was wired correctly with the brown wire going to the HEI and the red wire going to the keyed source on the fuse box, but I did not look on the back of the gauge itself to see if that is correct. I will double check to make sure it is wired correctly. I will also put a ground wire from the cluster to the chassis to ensure it is grounded properly. There is a ground strap going from the engine to the firewall.

Thanks for all the help. What would I do without this message board?
__________________
1969 Chevrolet C-10 SWB
Gennoy is offline   Reply With Quote
Old 01-03-2006, 05:28 PM   #10
Gennoy
Registered User
 
Gennoy's Avatar
 
Join Date: Nov 2005
Location: Antelope, CA
Posts: 21
Re: Factory Tach Install

Well, I thought I should give an update now that I figure out the problem. It is always the simplest thing. Thank you Longhorn Man for posting that picture of the back of the tach. I noticed on your picture that the tabs were pointed up and on mine they were pointed down. Which meant I had the wires backwards. After I rotated the tabs to look like yours I put on the V-connector and the truck fired right up. I guess I should have spent a little more time looking at the back of the gauge before I installed it. Owell, you live and you learn.

I also fixed the "Battery" gauge by replacing the two fuses as you guys suggested.

Thanks for everything.
__________________
1969 Chevrolet C-10 SWB
Gennoy is offline   Reply With Quote
Old 06-20-2007, 04:46 PM   #11
ChevyDude
Senior Member
 
Join Date: Jun 2003
Location: Westminster, CO
Posts: 3,071
Re: Factory Tach Install

I just had this INDENTICAL problem!!! Rotated the clips on the back of the tach and...it fixed everything! Gots a tach now!!!

Did a search on the board...found this thread...and the answer!!!
__________________
Alex


1971 Lil' Red 350 SBC 700R4

Last edited by ChevyDude; 06-20-2007 at 04:47 PM.
ChevyDude is offline   Reply With Quote
Old 06-20-2007, 06:04 PM   #12
Longhorn Man
its all about the +6 inches
 
Longhorn Man's Avatar
 
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,690
Re: Factory Tach Install

Wow, I can put the name of a thread in the search, and come up with a bunch of crap totally unrelated, you do it, and it gets you a 2 year old post on the exact subject.
Longhorn Man is offline   Reply With Quote
Old 06-20-2007, 06:07 PM   #13
BACKYARD88
On the fast track to nowhere..
 
BACKYARD88's Avatar
 
Join Date: May 2006
Location: Splendora, Texas
Posts: 5,316
Re: Factory Tach Install

Quote:
Originally Posted by Longhorn Man View Post
Wow, I can put the name of a thread in the search, and come up with a bunch of crap totally unrelated, you do it, and it gets you a 2 year old post on the exact subject.
Wurd
__________________
-Mike Owen-

Norwood, Houston, Cecilia, Jackson, Monroe and counting
BACKYARD88 is offline   Reply With Quote
Old 06-20-2007, 06:55 PM   #14
ChevyDude
Senior Member
 
Join Date: Jun 2003
Location: Westminster, CO
Posts: 3,071
Re: Factory Tach Install

I think I searched "brown tach wire" and found this Andy. Funny thing is ...it was exactly to the T what was wrong with my tach.
__________________
Alex


1971 Lil' Red 350 SBC 700R4
ChevyDude is offline   Reply With Quote
Old 06-20-2007, 07:14 PM   #15
WorkinLonghorn
Senior Member
 
WorkinLonghorn's Avatar
 
Join Date: Dec 2006
Location: Studio City, Calif.
Posts: 2,883
Re: Factory Tach Install

Gennoy said;
Quote:
So it seems the problem is with the new factory tach.
What I want to know is where do you find "new factory tachs" ? Unless he meant; "new cheap Korean-made tachs that are designed to look like factory ones". He hasn't posted in over a year so I quess I won't find out.
__________________
'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme.

Last edited by WorkinLonghorn; 06-20-2007 at 07:14 PM.
WorkinLonghorn is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 08:58 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com