Dash circuit boards

[sreidmx]

Hi guys has anyone used the printed circuit boards that lmc sells for $49? Mine was hacked and slashed by the Po and I need to have accurate gauges and I feel like this is one of the contributors to my issues with bouncing fuel gauge and misreading oil pressure(new sender) plus the lights on mine are dim. I know there is some cracks throughout and the new one is cheap.

I also have the dash from my 79 but wasn't sure and hadn't researched it that would work or not..

Thanks!
-Steve

 

[dyeager535]

How much effort do you want to put into your gauge working right?

Even brand new OEM I wouldn't trust the flex circuit to cure your problems. The connection (IP) is a terrible design, as are the sockets for all the bulbs. I feel the gauge connections are fairly solid, but that means nothing when the IP connector setup is as bad as it is.

I hard-wired mine, there is a thread I did that may be devoid of photos now (links changed, but I have them) but lists part numbers that I used and so on. For $50 you would probably come close with the crimping tool and all supplies needed, but its going to take time. However, there is no question the gauges will work as they should.

Sorry not much help on the LMC flex circuit, but I had enough problems with the stock setup (in apparently great physical condition) that I didn't feel like dealing with another/other problems down the road. They are a pain to remove from a complete dash, I didn't want to do have to pull it again once my dash was put together.

 

[sreidmx]

I'll look around, I am also not opposed to having some smaller gauges for redundancy on the truck. I need to get a couple more anyway for Egt, water and oil temps and voltage.

 

[dyeager535]

I'll look around, I am also not opposed to having some smaller gauges for redundancy on the truck. I need to get a couple more anyway for Egt, water and oil temps and voltage.

Personally I don't see the need for redundancy, once the cluster circuitry is "fixed". I know some have had actual gauge issues, but everything I've ever experienced, and I've dealt with hundreds of these clusters at this point, the gauges are not the problem (outside of a mechanical speedometer). I've got a set that was submerged for who knows how long, and it still works.

I'm fairly biased towards the factory gauges, I will admit that, but I think objectively they are still very robust, and from what I can tell, at least in terms of displaying the same value with the same sensor input, are accurate.

 

[sreidmx]

So as I understand what you mentioned in your first response you bypass the plug at the printed board completely and just rewire it into the gauges directly?

 

[dyeager535]

Pretty much.

All I did (general idea, not all the details) was find a Delphi connector that was fairly compact, and had enough terminals to accommodate all the wires I was trying to run, and used ring terminals on the connectors of each gauge. The 12V and grounds can be shared by all the gauges, and IIRC that should simplify wiring in your case as GM used at least two sets of 12V/grounds on the earlier clusters.
A separate wire for each sending unit to each gauge, any indicator lights, and the dash bulb feeds. That's it.

I also took the time to convert over to LED dash bulbs, with a PWM dimmer (fixed at the brightness I determined correct for me), and hard-wired those LED's to the cluster as well. That was a bit more work, as it is somewhat time consuming to modify 168/194 bulb holders to hold the LED's, and soldering the bulbs to the power/ground wires, but I should never have to deal with them again either.

None of the parts are particularly pricey to do the hard wiring, it's just a matter of time and motivation.

This should take you to the pics I took of the project: s831.photobucket.com/user/dyeager535/library/Truck/Cluster%20hard%20wire-LEDs%20C-K-R-V%20trucks%201973-1987%2091

Unfortunately, looks like I can't find the picture of the back of the cluster once completed. That is a '90-91 cluster, so the drilled printed circuit board you see (electric speedometer) won't apply to you.

 

[sreidmx]

I'll see if I can find a pin out of my trucks dash. Seems simple enough to do that and saves me 50$ minimum probably more. Thanks!

 

[dyeager535]

Here is my thread when I built it: https://ck5.com/forums/threads/hard-wiring-stock-instrument-cluster.304941/

At least the parts listing will give you an idea of what I used.

 

[6872xtc]

Just as an FYI, I bought a new printed circuit for my '72 C10 from LMC when I did the tach conversion. It works good so far, that truck isn't subjected to what yours will be off-road and dust wise...

 

[sreidmx]

Well Ethel is being put on possible long term DD so I do not wanna be removing and installing the dash all the time but I need functional dials.. I'm not 100% opposed to leaving it alone because of the lack of total molestation but I am also not sure how much I can trust it either.