BS3 and a LS1 PCM to run gauges COME IN!
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Joined: Dec 2006
Posts: 516
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From: Lynchburg, Va
BS3 and a LS1 PCM to run gauges COME IN! ok guys im running a LS1 PCM in my 94Z28, i hacked the wiring up myself a LONG time ago to run the LS in the LT car, now i need to further hack my harness to do a few things.
BS3 is gonna run everything engine management wise, all i want the stock PCM for is my gauges, i can get everything to run without the PCM due to being a LT1 all except for the speedometer, im running a 4l80E so the BS3 is running that too, however i am going to re route the PCMs speed signal from the front wheel like i did when i went th350 years back. my question is has ANYONE trimmed all the other sensors out and ran the PCM just for basic guages, and what powers and grounds are needed to do this? im running the tach signal to the stock gauges via BS3 so i dont need the CPS shared. so basically all i need the stock PCM for is the speedo, fans, and alternator functions, and retaining the DLC connector.
any help will be greatly appreciated, i have a scrap harness i can use for some misc pigtails. and the PCM connectors since i am gonig to sell my current swap harness.
BS3 is gonna run everything engine management wise, all i want the stock PCM for is my gauges, i can get everything to run without the PCM due to being a LT1 all except for the speedometer, im running a 4l80E so the BS3 is running that too, however i am going to re route the PCMs speed signal from the front wheel like i did when i went th350 years back. my question is has ANYONE trimmed all the other sensors out and ran the PCM just for basic guages, and what powers and grounds are needed to do this? im running the tach signal to the stock gauges via BS3 so i dont need the CPS shared. so basically all i need the stock PCM for is the speedo, fans, and alternator functions, and retaining the DLC connector.
any help will be greatly appreciated, i have a scrap harness i can use for some misc pigtails. and the PCM connectors since i am gonig to sell my current swap harness.
I may be too late. I what did you end up doing?
I am putting a BS3 in my car at this time. Looking at wiring prints we think we can make everything on the stock gauge cluster work except the speedo and the tach. Looking at the signal the cluster needs for the speedo we think we can make it work with a symple aftermarket module. I cannot remember the name of it right now but we use one in a 85 vett we installed a TKO 600 trans into. The kit came with this module and it works perfectly in the vett. It looks like the speedo in our cluster uses the same signal as the digital cluster in the vette. We have not tried it yet but if it works I will post the info up.
As for the tach we have not yet come up with the answer. But I have a fealing we might be able to do the same for it.
The rest of the gauges can be wired direct bypassing the PCM acording to the wiring printouts we have. These gauges are the oil pressure and coolant temp. The amp and fuel level gauges are working in my car right now with the BS3 in it and the stock PCM out of it. We have removed the body control module and wired everything needed that goes to it around it. Basically what I have done is removed both fuse/relay boxes that where in the engine bay and reinstalled it under the dash inside the car, stripping back and removing any wiring we did not need like the ABS, Cruise wireing, etc.. We only hooked back up the wiring to the boxes that we need for the car, lights, horn, etc.. There is one wire (yellow with a black strip) in one of the relay boxes that goes back to the BCM. The BCM module sends this wire to ground once it is saticfide. If you ground that wire directly the system will work without the BCM.
Now the BCM does a few other things but with a good printout you will see most of what it does is give permission for things to work as requested if all the control peramiters are met. Once the yellow/black striped wire is grounded most of what it controls is givine permission to function, like starting the car, roling windows up and down, etc.. So for we have not found anything that would require us to reinstall it. So far we have found ways to wire around it (like a 80's model car).
Long story short it looks like the cluster can be made to work by wiring it up direct on a few things, and using a speed convertor module on the speedo and maybe even the tach.
I am putting a BS3 in my car at this time. Looking at wiring prints we think we can make everything on the stock gauge cluster work except the speedo and the tach. Looking at the signal the cluster needs for the speedo we think we can make it work with a symple aftermarket module. I cannot remember the name of it right now but we use one in a 85 vett we installed a TKO 600 trans into. The kit came with this module and it works perfectly in the vett. It looks like the speedo in our cluster uses the same signal as the digital cluster in the vette. We have not tried it yet but if it works I will post the info up.
As for the tach we have not yet come up with the answer. But I have a fealing we might be able to do the same for it.
The rest of the gauges can be wired direct bypassing the PCM acording to the wiring printouts we have. These gauges are the oil pressure and coolant temp. The amp and fuel level gauges are working in my car right now with the BS3 in it and the stock PCM out of it. We have removed the body control module and wired everything needed that goes to it around it. Basically what I have done is removed both fuse/relay boxes that where in the engine bay and reinstalled it under the dash inside the car, stripping back and removing any wiring we did not need like the ABS, Cruise wireing, etc.. We only hooked back up the wiring to the boxes that we need for the car, lights, horn, etc.. There is one wire (yellow with a black strip) in one of the relay boxes that goes back to the BCM. The BCM module sends this wire to ground once it is saticfide. If you ground that wire directly the system will work without the BCM.
Now the BCM does a few other things but with a good printout you will see most of what it does is give permission for things to work as requested if all the control peramiters are met. Once the yellow/black striped wire is grounded most of what it controls is givine permission to function, like starting the car, roling windows up and down, etc.. So for we have not found anything that would require us to reinstall it. So far we have found ways to wire around it (like a 80's model car).
Long story short it looks like the cluster can be made to work by wiring it up direct on a few things, and using a speed convertor module on the speedo and maybe even the tach.
