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Old 10-05-2011, 11:21 PM   #1
C15_Sierra
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Speedo pin diagram?

Does anyone know what terminal is which on the back of an electric Burb/Blazer speedometer? I picked one up for my '80 GMC with a 5.3 swap, but I only have the speedo with the circuit board in the back, and I can't find a wiring diagram with the pinouts for the speedo. I gather I need +12v, ground, and VSS (already conditioned by the PCM) but I don't know which pin is which

Any help is appreciated! Thanks!
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1980 GMC C15 Sierra LWB
Dark Carmine Red/Carmine Int
Was: 250/3spd (1980-88), then a 305/TH350 (1988-2011)
Now: 5.3/4L60E, 2.73 12-bolt open rear
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Old 10-12-2011, 07:06 PM   #2
motornut
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Re: Speedo pin diagram?

my 89 4X2 burb...had random shots of the cluster with gauges plug, zoomed...
and back of my 78 just idiots
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Old 10-12-2011, 08:22 PM   #3
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Re: Speedo pin diagram?

maybe this
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Old 10-12-2011, 09:39 PM   #4
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Re: Speedo pin diagram?

Thanks John...I was actually looking for the pinout diagram for the circuit board attached directly to the speedo (inside the cluster) for the 90-91 speedo. I then figured I'd probably be better off just buying a damn cluster...so I called around to a bunch of yards, and turns out there was a 91 Suburban in a yard not too far from me, so I scored the entire cluster...and the mileage is only 10K off from mine



Side note: that Burb was in great condition (motor was bad) for being a Northeast truck...it was a conversion Burb too, with a really plush interior, kinda made me wish I used that as a chassis for my 5.3 swap
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1980 GMC C15 Sierra LWB
Dark Carmine Red/Carmine Int
Was: 250/3spd (1980-88), then a 305/TH350 (1988-2011)
Now: 5.3/4L60E, 2.73 12-bolt open rear
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Old 10-12-2011, 10:14 PM   #5
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Re: Speedo pin diagram?

oh k ......i miss my burbs.....they always started,can't say that for my GA
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Old 02-10-2012, 02:56 PM   #6
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Re: Speedo pin diagram?

did you get the info you needed? i did mine the "hard" way and just traced out each individual wire and put it where it went in the 90 cluster. i went to the junkyard and bought a second connector and moved 1 wire at a time.
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Old 02-10-2012, 03:10 PM   #7
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Re: Speedo pin diagram?

No, I just bought the cluster from the '91 Suburban and re-pinned the back. I've still got the spare sitting on my workbench. Someone who's smart would have traced the wires while he had the cluster out for future reference, but I guess I'm not that
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1980 GMC C15 Sierra LWB
Dark Carmine Red/Carmine Int
Was: 250/3spd (1980-88), then a 305/TH350 (1988-2011)
Now: 5.3/4L60E, 2.73 12-bolt open rear
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Old 02-10-2012, 03:29 PM   #8
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Re: Speedo pin diagram?

i didn't think it was too bad anyway. took me about a half an hour and a cup of coffee!
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Old 02-10-2012, 03:35 PM   #9
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Re: Speedo pin diagram?

Eh its not that I wasn't willing to do it, it's just that I wanted to move forward with that part of the project and get it done (at the time...I'm still not done with the truck lol)

I was just making fun of myself because usually I like to figure out how things work - I'm an engineer after all...
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-Steve

1980 GMC C15 Sierra LWB
Dark Carmine Red/Carmine Int
Was: 250/3spd (1980-88), then a 305/TH350 (1988-2011)
Now: 5.3/4L60E, 2.73 12-bolt open rear
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Old 02-10-2012, 03:41 PM   #10
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Re: Speedo pin diagram?

so you did get the electric one working then? did you repin the 20 wire (if i recall correctly) connector in the back or just put the electric speedo in from the burb?
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Old 02-10-2012, 04:01 PM   #11
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Re: Speedo pin diagram?

The cluster works as it should so far. The truck hasn't been on the road yet, plus I had the guy program the VSS output for 3.73 gears (currently the truck has 2.73s, but I plan on installing 3.73s eventually, and don't want to reprogram just for that) so I know the speedo will be off when I get it driving, which will hopefully be soon.

I did re-pin the cluster, and pending a full start-up I will see if the oil/water gauges work. Battery and fuel gauges work, and I've started the motor for about 20 seconds, but that was before I had the oil pressure sensor hooked up, and I didn't have coolant in the engine

Also - CEL, brake indicator, brights indicator all work, so I don't have any doubts that the rest of the cluster won't work as it should
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-Steve

1980 GMC C15 Sierra LWB
Dark Carmine Red/Carmine Int
Was: 250/3spd (1980-88), then a 305/TH350 (1988-2011)
Now: 5.3/4L60E, 2.73 12-bolt open rear
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Old 02-10-2012, 04:14 PM   #12
misternash2
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Re: Speedo pin diagram?

i got ya now. what's holding you up? i'd be happy to help you if i can. i love my truck so much more since i did the swap. and goody for me i'm getting ready to pull it and put it in a suburban!
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Old 02-10-2012, 04:28 PM   #13
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Re: Speedo pin diagram?

To actually answer your question though, the only thing the truck needs now is an exhaust to be road-worthy around town, and a new set of tires come spring to be highway-worthy. I have some more projects like interior work, suspension/cab bushings that I'll do, but the truck should be driveable once I get an exhaust done
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-Steve

1980 GMC C15 Sierra LWB
Dark Carmine Red/Carmine Int
Was: 250/3spd (1980-88), then a 305/TH350 (1988-2011)
Now: 5.3/4L60E, 2.73 12-bolt open rear
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Old 02-10-2012, 04:26 PM   #14
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Re: Speedo pin diagram?

For now, cold weather makes motivation for spending hours tinkering in the garage kinda tough. I'm also a little generous with my time helping out friends with their projects. Plus, I'm always tinkering with things at work, so sometimes when I go home I just need a break.

I had lots of small little side projects I wanted/needed done before I put the truck on the road. There's not too much motivation to get it on the road during the winter because I can't drive it too much - it's 2WD, plus I want to save it from the typical northeast truck doom because while0 there's very little rust, there's also very little paint on it. But it has been so mild I could have gotten away with it. Right now I'm focusing on getting things done right the first time so I don't have to keep tearing into it.

It's not for lack of knowledge (way too much on this site to use that excuse), just time and motivation (like any project)
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-Steve

1980 GMC C15 Sierra LWB
Dark Carmine Red/Carmine Int
Was: 250/3spd (1980-88), then a 305/TH350 (1988-2011)
Now: 5.3/4L60E, 2.73 12-bolt open rear
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Old 02-10-2012, 04:32 PM   #15
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Re: Speedo pin diagram?

i know how that goes! honey-do list gets backed up and gotta clear it off, at least thats how it is for me. what are you thinking for exhaust? i've got magnaflows on my swb, dumped before the axle. i'm worried about excessive interior noise in the burb. maybe some turndowns would help some. what do you think? i like a nice mellow tone, but definately not stock, if you get my drift.
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Old 02-10-2012, 04:34 PM   #16
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Re: Speedo pin diagram?

the magnaflows have an excellent sound that i love. i could run pipes in front of tires. tucked up underneath where they're not visible.
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Old 02-10-2012, 05:22 PM   #17
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Re: Speedo pin diagram?

I already have Flowmaster Super 40s, so I was thinking of doing a 2.5" true dual system w/ H-pipe, and turndowns right behind the rear tires, at the fender line for a kinda hidden look. I did think about keeping it simple with turndowns before the axle, but I really like the look of the first option and it would be nice to keep the drone out of the cab
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-Steve

1980 GMC C15 Sierra LWB
Dark Carmine Red/Carmine Int
Was: 250/3spd (1980-88), then a 305/TH350 (1988-2011)
Now: 5.3/4L60E, 2.73 12-bolt open rear
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Old 02-10-2012, 05:27 PM   #18
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Re: Speedo pin diagram?

yeah, i agree the drone is unacceptable. i don't have any at any speeds now, but not sure what's gonna happen with the burb.

i just realized that i've taken your post completely away from the point. i apologize. good luck with your build!
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