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6.2 to 454 swap...Gauge cluster interchangeability? Dorian?

Discussion in 'The Garage' started by Zeus33rd, Apr 4, 2006.

  1. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Swapping a 454 in place of the 6.2 in my '83 K20. Can I just unplug the wireing harness from the back of the gauge cluster/printed circuit and plug it into a cluster/printed circuit from a gas truck? Would I have to get one from the same year truck? Can I plug the 6.2 wiring harness into the various new sensors (oil pressure, temp) on the big block and have all the gauges work like they should? (assuming the cluster/printed circuit from a gas truck of course)

    I want to make this look as factory and neat as possible, so I don't really want a bunch of aftermarket gauges cluttering up the dash. I've already picked up a cluster with a factory tach on Ebay.

    And just incase, Does anyone have a wiring diagram/schematic for the printed circuit on the back of the cluster?:crazy:
     
  2. 1979jimmy350

    1979jimmy350 1/2 ton status

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    just get the dash wiring digram for the different years and just repin the connector it is very easy to do. As long as the connectors are the same yes you can use the orginal connectors on sensors
     
  3. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Is that something I'm gonna be required to do? lol, I was hoping someone would have a quick easy answer for me. I don't mind repinning the connector if I have too....I even figured it might come to that. Where would I find a diagram of the printed circuit thingy?
     
  4. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    ttt for Dorian. :D
     
  5. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    Why didn't you leave your old gauges and just remove the sending units from the diesel engine and install them in your big block? They'd probably screw right in to your old big block, waaaay easier than trying to get factory gauges to work with a newer engine with metric fittings.
    Oil pressure and coolant temp sending units, why not just transfer them over?
    what else is there, the tach would be different between diesel and gas engines? so get a new tach.?
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Lots of questions! :)

    The year differences are various. I have no idea where they split, there was a big difference with both the PCB and IP connector wiring from '89-90 obviously, previous to that, anybodies guess.

    The easiest way to do it is simply trace the PCB on the back of the cluster. Pull it, trace out the 12V and grounds, and mark them with a sharpie, if they aren't already. (another +1 for the 90-91 clusters, already marked from GM) That makes tracing the others easier. Knock out the stuff like turn signals, lights, then head on to the gauges. They SHOULD be wired the same as another cluster you use, given a similar vintage.

    You'll end up with some extra wires on the IP connector because of the diesel I expect (wait, water in fuel) but those can probably be left in place, as long as those pins don't go anywhere on the new cluster PCB.

    What I did on my truck because of all the changes made between the '90 and previous, was pull the earlier cluster, make an IP connector pinout (the connector is numbered or lettered for each cavity, and also fits in the IP only one way) showing which pin fed what item, and whether it was 12V, reference, or ground, then popped ALL the pins out. This way as I added say, a turn signal, I could plug the cluster back in, test, make sure it worked, then go to the next pin. You may not need to go to this extreme, but if you notice quickly that quite a few pins changed between the two besides the ones you will simply leave in place or remove, (again: wait light, etc) I'd advise this route. In my case the later cluster used one ground and one 12V feed, the earlier used a couple for lighting alone, which made it pretty confusing. Saved a lot of time by pulling all of them, but making sure each wire was identified by color and cavity which did what. I can't emphasize enough testing BEFORE you bolt anything back up. :)

    I second using at least the oil pressure sender and gauge from the diesel. It'll be an 80PSI unit, you need both the gauge and the sender. Gauge is an easy swap when the cluster is out. I *thought* the diesels had a different sweep to the coolant temp gauge, (240* max instead of 260*?) so you might not want to use it.

    Gas gauge is different, but only for people you might let use your truck and accidentally put diesel in because the gauge says so.

    Not sure if this applies, but in my state to make a diesel to gas conversion legal, you have to remove all the diesel identifying stuff, which means the gauge, and the sticker at the gas door. Just FYI, probably not an issue for you, but something to think about while you have it apart, and since you have the gas gauge already, a moot point, unless it doesn't work right.

    Again unsure at what point this changed, but my '90-91 cluster has the 4wd indicator light integrated into the IP connector. Earlier (1980 for sure) there was a separate harness for this. The diesel wait light harness was also "separate" from the diesel harness I had, so you can probably unplug it somewhere close to the fuse panel and simply remove the wiring. Better than just cutting wires and leaving them. If you end up having to cut wires to get them out of the IP connector because they aren't used, make sure to seal the ends up VERY well so that they can't short to the body, and it woudln't be a bad idea to label what they were, so whoever is in there next in however many years, doesn't see it and wonder what the heck it is supposed to go to.
     
  7. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Thanks for the replies dudes.

    It seems like it would be a good idea to just use the diesel sending units in the big block. The diesel temp gauge IS different....240* max. Easy enough to swap that out though. Will the diesel temp sending unit work with a gas gauge?


    There is one large connector on the back of the cluster, a seperate connector for the 4wd light, and one for the glow plug light and water in fuel light.

    I don't think the fuel gauge will be a problem. Will a gas fuel gauge work with the diesel tank sending unit? I can't imagine why not...

    Next question....How can I be sure to get as much of the diesel out of the tanks as possible? I suppose I could just run one of them almost empty, then remove it to get the leftovers out. Unless there's an easier way...hehe
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    You'd need to use the diesel sender/gauge combination for temp or oil pressure, since the range of the gauge/sender is different.

    Gas fuel gauge will work fine with the diesel sender, same wiring setup in all the tanks.

    Diesel portion, can't help you much other than just removing it. You'll need to remove the filler and large vent line to pull the tank anyway, if you've got a decent size diameter hose that is flexible enough, you could siphon once you pulled those.

    Fairly painful pulling the tank, but once you get it out removing the sending unit is easy, then you can just turn the tank over, or tilt and siphon out of one corner, then wipe it out. Diesels have some sort of weird sender apparently, I'd be interested in seeing the design when you get to the point of pulling it.
     
  9. DavidB

    DavidB 1/2 ton status

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    Hey, Jethro, how's it goin'? Your 6.2 didn't kill my 'runner on the way home, but it killed the mileage. Andy didn't like the fuel bill :D


    How'd this turn out? I wanna do the reverse or this swap, only with a '93 6.5 TD. Wondering about all that wiring. Prollly need to see it for it all to make sense.
     

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