Help with instrument cluster - 77 K10

[Dleslie212]

I am trying to buy a new printed circuit board for my 77 K10. I had LMC Truck email me a picture of the boards they have for 77, but it doesn't match up to what I have. I found a number on my old board, and Googling brings this up, which is exactly what mine looks like.

https://www.summitracing.com/parts/ado-25044897

From what I can tell, this particular board was for 85-86. So I'm thinking somebody swapped out the gauge assembly at some point.

I also found this:

https://www.ebay.ca/itm/73-87-Chevy...ash=item4208ad8395:g:Y64AAOSwtYJdV1Xg&vxp=mtr

Which is exactly what my cluster housing looks like, minus the hole for the clock at the bottom left - mine is just blank plastic.

My question is, which circuit board should I get? The one for the 77? Would that even fit on my cluster housing if the cluster housing is from 85-86 (I don't know that it is)

 

[chengny]

I am trying to buy a new printed circuit board for my 77 K10. I had LMC Truck email me a picture of the boards they have for 77, but it doesn't match up to what I have. I found a number on my old board, and Googling brings this up, which is exactly what mine looks like.

https://www.summitracing.com/parts/ado-25044897

From what I can tell, this particular board was for 85-86. So I'm thinking somebody swapped out the gauge assembly at some point.

I also found this:

https://www.ebay.ca/itm/73-87-Chevy...ash=item4208ad8395:g:Y64AAOSwtYJdV1Xg&vxp=mtr

Which is exactly what my cluster housing looks like, minus the hole for the clock at the bottom left - mine is just blank plastic.

My question is, which circuit board should I get? The one for the 77? Would that even fit on my cluster housing if the cluster housing is from 85-86 (I don't know that it is)

It looks like that bucket (case) shown in the link is part number 25051838. That P/N shows as used in the C/K 1,2 & 3 series for model years 1983 & 84. It appears to accept printed circuit with P/N 25044897 (C/K 1, 2 &3 without tach). The only thing that doesn't seem correct is that it is described as not having a clock?

 

[Dleslie212]

It looks like that bucket (case) shown in the link is part number 25051838. That P/N shows as used in the C/K 1,2 & 3 series for model years 1983 & 84. It appears to accept printed circuit with P/N 25044897 (C/K 1, 2 &3 without tach). The only thing that doesn't seem correct is that it is described as not having a clock?

That's correct, the spot on the bottom left where the clock would be has not been punched out. So should I be getting the circuit board for a 83-84? Or should the 77 board work on the cluster housing that I have? Here are a few pics I just took of what I pulled out

https://imgur.com/O5Y4S4Q
https://imgur.com/RJWYPt8
https://imgur.com/Hik0q2d

Edited to add:

Here is the picture LMC Truck sent me of the 77 board, their part number is 38-8037
https://imgur.com/xPd8JK6

 

[Dleslie212]

I am adding a few more pics I took of the cluster wiring harness, hoping somebody can point me in the right direction. I also read in a post from here that the 77 only came factory with a mechanical oil pressure gauge - electric didn't start until 78. Mine is electric, and is one of the only gauges that actually DO work. So now I'm thinking the harness must have been changed out as well? If that's the case, I'm assuming I should just get whatever works for the harness year-wise, so that I don't have to replace the harness again?

Also, I've found this: https://www.classicparts.com/1981-87-Instrument-Cluster-Circuit-Chevy/productinfo/24-489GT/

Which looks exactly like the circuit board I pulled off - but not the same as what LMC Truck has listed for the same year? Anybody know why?

Here are a few pics of my cluster wiring harness -

https://imgur.com/miBCynz
https://imgur.com/JfCZ4oT
https://imgur.com/1hwrX2k

 

[chengny]

I would stick with the 25044897 circuit. The connectors for the 77 and the 81-84 are not compatible. There do not even use the same number of tabs. That and the fact that the circuit for the 81 - 84 shows as correct (see below):

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To revert back to the 77 harness would require some serious re-pinning.

 

[Dleslie212]

I would stick with the 25044897 circuit. The connectors for the 77 and the 81-84 are not compatible. There do not even use the same number of tabs. That and the fact that the circuit for the 81 - 84 shows as correct (see below):

You must be registered for see images attach

To revert back to the 77 harness would require some serious re-pinning.

My main concern is the possibility that the previous owner threw 81-84 gauge assembly in there, without replacing the harness. Can anybody tell from the pictures I posted whether that is the harness for a 77, or the harness for an 81-84?

 

[C10MixMaster]

My main concern is the possibility that the previous owner threw 81-84 gauge assembly in there, without replacing the harness. Can anybody tell from the pictures I posted whether that is the harness for a 77, or the harness for an 81-84?

The clusters from 73-91 all used the same connector they are just pinned different. If the oil gauge works the some one added wiring or replaced it with a newer harness. here's the pinouts for both. I would use the circuit board that matches the gauges These are real easy to repin..

You must be registered for see images attach

You must be registered for see images attach

 

[Dleslie212]

The clusters from 73-91 all used the same connector they are just pinned different. If the oil gauge works the some one added wiring or replaced it with a newer harness. here's the pinouts for both. I would use the circuit board that matches the gauges These are real easy to repin..

You must be registered for see images attach

You must be registered for see images attach

I actually saw this table a few days ago, but some things don't line up - my dark blue wire is on pin 12, which is not listed on that table anywhere. Dark blue only shows as 1, 3 or 5 on the table. Also, I have two pink wires at pin 18, and the table doesn't show pink at pin 18 anywhere. Any suggestions?

 

[Dleslie212]

Here are the colors going to the pins in the harness. There are some pictures above if it helps any

Pin -------- Color

1 - Light Green
2 - Grey
3 - Black
4 - Pink w/ black stripe
5 - Brown (maybe tan, hard to tell if the wire is just discolored)
6 - Pink
7 - Pink
8 - Black
9 - Dark Green
10 - Black
11 - Light Blue
12 - Dark Blue
13 - Yellow
14 - Blank, no wire
15 - Blank, no wire
16 - Pink w/ black stripe
17 - Brown w/ white stripe + tan w/ white stripe (two wires in pin 17)
18 - Pink + Pink (two wires in pin 18)

I just can't find anything in the table above that matches.

 

[C10MixMaster]

Here are the colors going to the pins in the harness. There are some pictures above if it helps any

Pin -------- Color

1 - Light Green
2 - Grey
3 - Black
4 - Pink w/ black stripe
5 - Brown (maybe tan, hard to tell if the wire is just discolored)
6 - Pink
7 - Pink
8 - Black
9 - Dark Green
10 - Black
11 - Light Blue
12 - Dark Blue
13 - Yellow
14 - Blank, no wire
15 - Blank, no wire
16 - Pink w/ black stripe
17 - Brown w/ white stripe + tan w/ white stripe (two wires in pin 17)
18 - Pink + Pink (two wires in pin 18)

I just can't find anything in the table above that matches.

looks closest to the 78-82 harnesses . when parts get mixed from different years these things happen. No telling exactly what the previous owner did and its possible there are others variations not on the table above. there are other wires not shown also, for example i believe one of the pink and black striped wires are for the seat belt light. The color codes seam remained fairly consistent. When i swapped a 91 cluster into my 77 i went through this. What i ended up doing tracing the circuits on the cluster, for example the gas gauge wire traced it back to pin 7 and did that for all 18 pins. then i used the chart above for a reference on the wiring. then repinned it to match. If your 77 has blade fuses and not glass fuses the harness is not original and has been updated.

 

[Dleslie212]

looks closest to the 78-82 harnesses . when parts get mixed from different years these things happen. No telling exactly what the previous owner did and its possible there are others variations not on the table above. there are other wires not shown also, for example i believe one of the pink and black striped wires are for the seat belt light. The color codes seam remained fairly consistent. When i swapped a 91 cluster into my 77 i went through this. What i ended up doing tracing the circuits on the cluster, for example the gas gauge wire traced it back to pin 7 and did that for all 18 pins. then i used the chart above for a reference on the wiring. then repinned it to match. If your 77 has blade fuses and not glass fuses the harness is not original and has been updated.

It does have blade and not glass. I just got finished taking a look at all the wiring - it's is an absolute rat's nest. I don't know how I'm going to get that sorted out.