New cluster/gauge install…Nothing works!!!

[Cu1n81]

Guys, I have a 79 c10 with a 5.7 350. I bought the truck from a guy who stripped it down and basically didn’t have anything stock on it gauge wise. My goal has been to return the cluster/gauges/bezel back to the stock year.

I bought all the gauges from LMC with the tach as an option. The previous owner had dash gauges that he wired directly to the gauge itself vs having a printed circuit. I’m trying to go back to the printed circuit. I have spliced all the wires back until the harness like I believe it goes.

I will attach a pic of the harness and a wiring diagram that I followed to reconnect the wires to the 18 pin connector. The issue I’m having is when I plug in the connector none of the gauges work. The only one working is the tach, which is directly wired and not thru the printed circuit.

My concern is the connector is wired for a truck without a tach and my circuit is made for the tach option. Is that why the 4 gauges (oil, volt, gas, and temp) aren’t working? I have no clue what this truck was out of the factory. Any help is appreciated.

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[dsteelejr]

I did the exact same thing you are doing on my ‘80 K25, except my reason for it was it had idiot lights and I wanted factory style gauges.

First thing to check is power to the small gauges. There is a pink & black wire, circuit 39, that goes into three terminals on the connector. That pink & black wire feeds “IGNITION ON & CRANK” power to the gauges when you turn key on. Using a circuit tester or volt meter check that wire to see if it has power when the key is on.

 

[Bextreme04]

Also make sure your ground is there and connected(cleanly) to the tabs sticking out of the top of the parking brake mounting bracket.

Also, did you make sure that pinout was for a 79? There are different pinouts for different years. There are electrical schematics for all years located in the reference library forum on this site.

 

[dsteelejr]

My concern is the connector is wired for a truck without a tach and my circuit is made for the tach option.

I forgot to mention, the way the connector is pinned is the same for gauges without tach and gauges with tach. You would only need to repin the connector if you were going from idiot lights to gauges as in my situation. The tach doesn’t use anything from the connector.

 

[dsteelejr]

Also, did you make sure that pinout was for a 79? There are different pinouts for different years.

From what I’ve seen the connectors are pinned the same for 76 - 86.

‘73 - ‘75 had ammeters instead of volt meters and mechanical oil pressure gauges, as well as different bulk head connectors and glass tube fuses so they were set up different. And with going to EFI in ‘87 I believe they changed it again.

 

[Bextreme04]

From what I’ve seen the connectors are pinned the same for 76 - 86.

‘73 - ‘75 had ammeters instead of volt meters and mechanical oil pressure gauges, as well as different bulk head connectors and glass tube fuses so they were set up different. And with going to EFI in ‘87 I believe they changed it again.

This is not true... I have seen many posts on various forums of people smoking clusters because they bought one from a different year and thought they were just plug and play. You need to look at the specific wiring diagrams for your year and verify that you are using the correct pinout for that year. If you go on LMC and look at all of the different printed circuits for gauge clusters, you'll see that they have numerous year breaks, even for the same gauge layout.

Just look at the one for "Gauges w/o tach for 73-80" There is a 73-75, two different 76 ones, a 77 specific one, and then 78-80. All for the exact same gauge's and gauge layout.... what do you suppose they changed? I would bet it is the ribbon layout to the pins on the connector... which are in different locations for some of those years

 

[dvdswan]

Soooo,

Being that the PO install aftermarket gauges, I wonder why. Did it come with gauges originally? Was the original wiring there?

If so, you will need to be sure the connections are there on the engine side.

The gauges are simple function; ground, component, and power at the cluster. So from your cluster connector, verify you have a good ground as this is the easiest, then verify your gauges, 1 wire to temp sender, 1 wire to oil press sender, and 1 wire to alt. then verify the KO power.

Use a multimeter to verify your wires to components to ensure they are not shorted to ground.

Also, the tach is not wired through the connector, it is wired by its own 2 pin connector.

Another note, hopefully the connector is not wired 180* out. So verify pin 1 actually hits pin 1.

 

[Cu1n81]

Just to update my situation, the gauges all worked except the voltmeter. I think it may have fried it on hookup. I had a blown/melted fuse. Once I changed the fuse I put another voltmeter in, but wired it directly to ground/12v ignition and bypassed the printed circuit. Now all my gauges are working via the printed circuit minus the voltmeter. I ordered the 73-80 gauges with tach option. For the most part it was plug and play. I did add some led back lighting. Looks pretty cool at night. I’m very pleased. Thanks for the replies. I’ve learned a lot.

***still waiting on Speedo driven gear and housing before I can get the Speedo working. Cable is new. Just need the gear and housing. Should be here Tuesday.

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[Shorty81]

Just to update my situation, the gauges all worked except the voltmeter. I think it may have fried it on hookup. I had a blown/melted fuse. Once I changed the fuse I put another voltmeter in, but wired it directly to ground/12v ignition and bypassed the printed circuit. Now all my gauges are working via the printed circuit minus the voltmeter. I ordered the 73-80 gauges with tach option. For the most part it was plug and play. I did add some led back lighting. Looks pretty cool at night. I’m very pleased. Thanks for the replies. I’ve learned a lot.

***still waiting on Speedo driven gear and housing before I can get the Speedo working. Cable is new. Just need the gear and housing. Should be here Tuesday.

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Well, that turned out really nice!! Good job.

 

[PeteJr]

Just to update my situation, the gauges all worked except the voltmeter. I think it may have fried it on hookup. I had a blown/melted fuse. Once I changed the fuse I put another voltmeter in, but wired it directly to ground/12v ignition and bypassed the printed circuit. Now all my gauges are working via the printed circuit minus the voltmeter. I ordered the 73-80 gauges with tach option. For the most part it was plug and play. I did add some led back lighting. Looks pretty cool at night. I’m very pleased. Thanks for the replies. I’ve learned a lot.

***still waiting on Speedo driven gear and housing before I can get the Speedo working. Cable is new. Just need the gear and housing. Should be here Tuesday.

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The "new & improved" version looks great, Jason.
I'm in the middle of the same update on mine.
Thanks for posting.

(BTW, As a Carolina boy, I've been thru Aynor many times going to "The Beach")

 

[jrico]

Little late to the party, but do you know which direction to plug the harness in? It looks like it can plug in either direction. What side of the cluster back does the #1 pin go?

 

[Randy and Easton]

harness only goes in one direction Into cluster. Look at the connect pins and you will see the slightly different sizes. Easy to get it wrong, but when you do you will not feel it “lock or click” into place.

 

[jrico]

Thanks I appreciate the heads up.