factory tach - The 1947 - Present Chevrolet & GMC Truck Message Board Network

sox8145 · 11-18-2011, 07:13 PM

whats up guys! I just bought a gauge cluster with the factory tach off an 80 model chevy for my 85 chevy swb. I looks to be in working condition but it didnt come with the wireing harness for the tach. I no how to hook it up with out the harness but i would like to have one. Does anyone know where i could get one? Do they even make them anymore? Or am i just gonna have to hook it up with out one.

rocking chevy · 11-18-2011, 08:01 PM

Im guessing you'll have to hook it up without one, no one makes a aftermarket tach so I'm guessing no one makes the wiring harness.

GM72K10 · 11-18-2011, 09:46 PM

Try these guys:
http://www.ebay.com/itm/1979-82-Chev...item45feb15303

ozark · 11-19-2011, 10:03 AM

I bought my tach harness from the guy in the link. It is good quality.

motornut · 11-20-2011, 09:09 AM

make sure to check/move the wires on the main plug
all 3 types of clusters are wired differently

Jonboy · 11-20-2011, 11:23 PM

I just ran my own wires. The tach should be labeled. All you need is tach signal (from the distributor or coil), switched 12V+ and ground.

motornut · 11-20-2011, 11:59 PM

I's the cluster wires that's different,
The plug with 18 holes , those wires need to move, the wires for the turn markers, gas gauge, they all move around into different spots
Only the 1 and 2 spots I think stay the same, Even if you had gauges before
Posted via Mobile Device

motornut · 11-21-2011, 01:19 PM

actually most are the same if gauges
i just did mine, i made this for ez reference,should work for you too,let me know

75gmck25 · 11-26-2011, 11:24 AM

On my '75 the wiring for the factory tach is a separate 3-wire plug. As someone else said, you just need switched power, ground and tach signal. I have the factory pigtail on mine and it just a simple 3 wire plug (looks a little like a 5 wire relay plug with some terminals cut off).

You should also know that these tachs are relatively unreliable because they get bad circuit traces that cause intermittant operation. A replacement tach board will fix it, but the only ones I've found have been for Corvettes. I took my tach apart to verify that the tach board in the truck is not the same shape as a Corvette one.

A factory tach also had a tach filter where you connect it to the HEI. It will work without one, but may get some ignition interference. A factory replacement tach filter is fairly expensive, but I've seen several circuit diagrams and its a very simple device to make yourself with Radio Shack parts. However, I don't have one on my truck and it seems to work fine.

Bruce

motornut · 11-26-2011, 12:46 PM

mine is right on with the other one
ran it off the cluster feed pink for me
not sure if i'm gona leave the other one but for now it's all good
only the speedo in this is mine from before
I too was lucky to get the tach plug

11-18-2011, 07:13 PM	#1
sox8145 Registered User Join Date: Sep 2011 Location: Levelland Tx Posts: 62	factory tach whats up guys! I just bought a gauge cluster with the factory tach off an 80 model chevy for my 85 chevy swb. I looks to be in working condition but it didnt come with the wireing harness for the tach. I no how to hook it up with out the harness but i would like to have one. Does anyone know where i could get one? Do they even make them anymore? Or am i just gonna have to hook it up with out one.

11-18-2011, 08:01 PM	#2
rocking chevy Registered User Join Date: Apr 2011 Location: Nebraska Posts: 262	Re: factory tach Im guessing you'll have to hook it up without one, no one makes a aftermarket tach so I'm guessing no one makes the wiring harness.

11-18-2011, 09:46 PM	#3
GM72K10 Next! Join Date: Jan 2003 Location: Eastern Pa. Posts: 2,483	Re: factory tach Try these guys: http://www.ebay.com/itm/1979-82-Chev...item45feb15303 __________________ 86 K30 CUCV M1028A1 86 K30 CUCV M1028a2 dually 86 K30 C&C 6.2 4:56s, 4M, 11,000 gvw, ex fire truck, now lowboy dump More square bodies and CUCVs than I care to admit to 2020 Silverado K3500HD Work truck

11-19-2011, 10:03 AM	#4
ozark Registered User Join Date: Jan 2008 Location: Eureka Springs AR Posts: 179	Re: factory tach I bought my tach harness from the guy in the link. It is good quality.

11-20-2011, 09:09 AM	#5
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: factory tach make sure to check/move the wires on the main plug all 3 types of clusters are wired differently __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350

11-20-2011, 11:23 PM	#6
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	Re: factory tach I just ran my own wires. The tach should be labeled. All you need is tach signal (from the distributor or coil), switched 12V+ and ground. __________________ 1974 Jimmy- 5.3/4L80e/NP241

11-20-2011, 11:59 PM	#7
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: factory tach I's the cluster wires that's different, The plug with 18 holes , those wires need to move, the wires for the turn markers, gas gauge, they all move around into different spots Only the 1 and 2 spots I think stay the same, Even if you had gauges before Posted via Mobile Device __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350

11-21-2011, 01:19 PM	#8
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: factory tach actually most are the same if gauges i just did mine, i made this for ez reference,should work for you too,let me know Attached Images __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350 Last edited by motornut; 11-21-2011 at 01:36 PM.

11-26-2011, 11:24 AM	#9
75gmck25 Registered User Join Date: Nov 2007 Location: San Antonio, TX Posts: 28	Re: factory tach On my '75 the wiring for the factory tach is a separate 3-wire plug. As someone else said, you just need switched power, ground and tach signal. I have the factory pigtail on mine and it just a simple 3 wire plug (looks a little like a 5 wire relay plug with some terminals cut off). You should also know that these tachs are relatively unreliable because they get bad circuit traces that cause intermittant operation. A replacement tach board will fix it, but the only ones I've found have been for Corvettes. I took my tach apart to verify that the tach board in the truck is not the same shape as a Corvette one. A factory tach also had a tach filter where you connect it to the HEI. It will work without one, but may get some ignition interference. A factory replacement tach filter is fairly expensive, but I've seen several circuit diagrams and its a very simple device to make yourself with Radio Shack parts. However, I don't have one on my truck and it seems to work fine. Bruce

11-26-2011, 12:46 PM	#10
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: factory tach mine is right on with the other one ran it off the cluster feed pink for me not sure if i'm gona leave the other one but for now it's all good only the speedo in this is mine from before I too was lucky to get the tach plug Attached Images __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350 Last edited by motornut; 11-26-2011 at 12:52 PM.



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