tach guage cluster wiring - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72SWB4X4 · 01-30-2004, 07:46 PM

can someone tell or show me the wiring diagram for the connector in the back of the guage cluster ?

Low69CST · 01-30-2004, 08:26 PM

I think if you go to painlesswiring.com, they have their instruction manuals online. They use the same plug as OEM so it should have it all laid out for you. I have the manual at my dad's shop i can get you tomorrow if it isn't online.

72SWB4X4 · 01-30-2004, 08:54 PM

ok i have done some testing of the sender wire and the temp guage and the wiring harness and the voltage at the guage cluster

sender wire has no ohm drop from the pin on guage plug to the sender on the motor...

temp guage reads 54.2 ohms resitance across the two side terminals

voltage at the guage on the printed circuit reads 12.8 volts on one side and 7.4 volts on the other

Longhorn Man · 01-30-2004, 08:57 PM

You need to know the wires for the entire harness, or just the tach its self?
The tab that says 12 volt needs to go to a power source that is controlled with the key. One of the IGN UNFUSED terminals on the fuse box is good. The other one goes to the negitive post on the coil if you still have the old points set up, or to the TACH terminal on the HEI cap if you have HEI.

72c10step · 01-30-2004, 10:26 PM

Wow Longhorn Man, that's one clean back of a gauge bezel. I'm trying to clean one up myself, its got a nice layer of surface rust on it. Should I just sandblast it and leave it metal, or put some paint on it?

Longhorn Man · 01-30-2004, 10:28 PM

For the record...that is not mine.
I toss mine in the bead blaster at work, and then clear coat it on the back, and paint the inside white to get a better light with the dash lights. Then I grind down where the bolts all go in so the grounds won't be an issue.

72c10step · 01-31-2004, 06:14 PM

Thanks Longhorn Man, thanks what I figured, otherwise it'd just rust up again. Looks like I gotta bring mine into work to use the bead blaster there

billtoothaker · 02-16-2004, 07:30 PM

New here. I have a 72 K20 with 63K 350Cu. I installed a tach in the cluster with a new circuit ribbon, hooked the 12 volt to a ignition on hot wire, and the other to the HEI terminal on the cap. When the engine runs the tach reads 800 RPM and does not move, is the tach faulty or is there another explaination?

Rod · 02-16-2004, 09:57 PM

I have seen the tach needles get stuck from dirt and dust inside the tach head itself. Most can be cleaned up and made to work. I can adjust the needle also so it rests at 0 rpm when it not running also. Make sure the cluster itself has a ground to the dash so it completes the circuit. Maybe just connect some wire to the dash metal backing plates and ground it somewhere to see if that allows the needle to move also.

billtoothaker · 02-17-2004, 09:21 AM

Thanks Rod, When the ignition is off it reads 0 RPM but goes to 800 when the engine starts. As Much as I hate to I will take the cluster back out and take the tach out and clean it. If I take the 2 screws off the front of the tach itself, will there be springs and other stuff popping out?

01-30-2004, 07:46 PM	#1
72SWB4X4 Florida Key's Member Join Date: May 2003 Location: Key West Florida Posts: 143	tach guage cluster wiring can someone tell or show me the wiring diagram for the connector in the back of the guage cluster ? __________________ Craig Wood 1972 SWB Chevy Cheyenne 4X4 Restored stock except 454 (481 cu. in. now) most options Available pictures of my truck http://myoldtruck.com/gallery/browse...500&userid=528 Come to florida and visit www.Paradisewatersports.com

01-30-2004, 08:26 PM	#2
Low69CST Registered User Join Date: May 2000 Location: Frankfort, Kentucky, USA Posts: 2,163	I think if you go to painlesswiring.com, they have their instruction manuals online. They use the same plug as OEM so it should have it all laid out for you. I have the manual at my dad's shop i can get you tomorrow if it isn't online. __________________ '69 CST Short fleetside Lowered, 400 small block, 700R4, 4 wheel disc brakes, front sway bar & rear camaro sway bar (in progress) '87 V10 4x4 Short Fleetside Quad Suspension and Dual Tanks

01-30-2004, 08:54 PM	#3
72SWB4X4 Florida Key's Member Join Date: May 2003 Location: Key West Florida Posts: 143	update ok i have done some testing of the sender wire and the temp guage and the wiring harness and the voltage at the guage cluster sender wire has no ohm drop from the pin on guage plug to the sender on the motor... temp guage reads 54.2 ohms resitance across the two side terminals voltage at the guage on the printed circuit reads 12.8 volts on one side and 7.4 volts on the other __________________ Craig Wood 1972 SWB Chevy Cheyenne 4X4 Restored stock except 454 (481 cu. in. now) most options Available pictures of my truck http://myoldtruck.com/gallery/browse...500&userid=528 Come to florida and visit www.Paradisewatersports.com

01-30-2004, 08:57 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	You need to know the wires for the entire harness, or just the tach its self? The tab that says 12 volt needs to go to a power source that is controlled with the key. One of the IGN UNFUSED terminals on the fuse box is good. The other one goes to the negitive post on the coil if you still have the old points set up, or to the TACH terminal on the HEI cap if you have HEI. Attached Images

01-30-2004, 10:26 PM	#5
72c10step WHYBYNU when old will do? Join Date: Jul 2003 Location: Loudon, NH Posts: 876	Wow Longhorn Man, that's one clean back of a gauge bezel. I'm trying to clean one up myself, its got a nice layer of surface rust on it. Should I just sandblast it and leave it metal, or put some paint on it? __________________ -72 Chevy C10 Stepside -2002 Chevy Silverado 2500HD 4x4 -1984 Jeep CJ7 -1995 Polaris XCR600 Custom -2003 Honda 300ex

01-30-2004, 10:28 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	For the record...that is not mine. I toss mine in the bead blaster at work, and then clear coat it on the back, and paint the inside white to get a better light with the dash lights. Then I grind down where the bolts all go in so the grounds won't be an issue.

01-31-2004, 06:14 PM	#7
72c10step WHYBYNU when old will do? Join Date: Jul 2003 Location: Loudon, NH Posts: 876	Thanks Longhorn Man, thanks what I figured, otherwise it'd just rust up again. Looks like I gotta bring mine into work to use the bead blaster there __________________ -72 Chevy C10 Stepside -2002 Chevy Silverado 2500HD 4x4 -1984 Jeep CJ7 -1995 Polaris XCR600 Custom -2003 Honda 300ex

02-16-2004, 07:30 PM	#8
billtoothaker Junior Member Join Date: Feb 2004 Location: Rochester, NH Posts: 92	Tach not working New here. I have a 72 K20 with 63K 350Cu. I installed a tach in the cluster with a new circuit ribbon, hooked the 12 volt to a ignition on hot wire, and the other to the HEI terminal on the cap. When the engine runs the tach reads 800 RPM and does not move, is the tach faulty or is there another explaination? __________________ Bill Toothaker 72 K20 FSLB 63K FS:86 Mercedes 560SL 63 Ford F100 51 Willy's Jeep station wagon w/64 289 Studebaker 68 Honda SL90 1500 miles Chevy 6 cyl street rod 2011 Nissan Murano cross cabriolet Cabins for Rent Lake Winnipasaukee, NH

02-16-2004, 09:57 PM	#9
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	I have seen the tach needles get stuck from dirt and dust inside the tach head itself. Most can be cleaned up and made to work. I can adjust the needle also so it rests at 0 rpm when it not running also. Make sure the cluster itself has a ground to the dash so it completes the circuit. Maybe just connect some wire to the dash metal backing plates and ground it somewhere to see if that allows the needle to move also. __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

02-17-2004, 09:21 AM	#10
billtoothaker Junior Member Join Date: Feb 2004 Location: Rochester, NH Posts: 92	Tach not working Thanks Rod, When the ignition is off it reads 0 RPM but goes to 800 when the engine starts. As Much as I hate to I will take the cluster back out and take the tach out and clean it. If I take the 2 screws off the front of the tach itself, will there be springs and other stuff popping out? __________________ Bill Toothaker 72 K20 FSLB 63K FS:86 Mercedes 560SL 63 Ford F100 51 Willy's Jeep station wagon w/64 289 Studebaker 68 Honda SL90 1500 miles Chevy 6 cyl street rod 2011 Nissan Murano cross cabriolet Cabins for Rent Lake Winnipasaukee, NH



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