Poor mans electronic speedo conversion

supwicha

Veteran Member
Feb 23, 2014
185
Victorville, CA
cvhu said:
i dont have any way of calibrating the speedo thru the pcm without sending pcm away or buying a programmer to do it, if u have a way and would like to share that would be great, i sent my pcm out last year and had it reprogrammed with all the mods i have done, also its just to see i could get this speedo to work and be fairly accurate

Well, what I did was purchased a USB to ALDL cable ($80), Tunercat Winflash ($20), and Tunerpro (Free from tunerpro.net), as well as some free BIN files and tables. I downloaded my original BIN file from my PCM and edited the file with "tunerpro", then uploaded the changes with "winflash". What year is your PCM? I am assuming it is '96 or newer, so you would need a different cable and software, but either way you can modify parameters to account for tire size, gear ratios, etc. I'll have to let you know how my calibrations turn out once the car is derivable.
 

supwicha

Veteran Member
Feb 23, 2014
185
Victorville, CA
hogg said:
I would like to here more of this , and with out the elect. turms,,,pcm,vss,vssb,,, Just all the parts i would need from another car to make all gauages work ? back to the top

To be truthful, it is a work in progress but looks to be hopeful. Just in case you need the information:

PCM (Powertrain Control Module - Computer)

VSS (Vehilce Speed Sensor - Located in the tail of the transmission)

VSSB (Vehilce Speed Sensor Buffer - Used to calibrate the speedometer without changes to the PCM - FYI I'm not using this)

As far as parts go, I used all of the factory gauges from my '78 Camaro except for the speedometer.

For the tachometer signal, I picked up this from pin A13 from my PCM rather than the coil. The coil works as well but requires a filter for noise.

For the speedometer, I used a cluster from a 2005 Chevrolet Aveo (Ebay $18 free shipping) - (I think '04 to '08 are the same). You will need to use the original circuit board that comes with the cluster. You will need to unsolder the gauge "motors" from the circuit board.

You will take the speed signal from your computer and wire it to the circuit board of the aveo. You will have some wiring from the circuit board of the aveo to the speedometer that you modify and fit in your cluster.

I know this is not very good detail, once I get it all ironed out and verified functional, I'll do a detailed step by step tutorial.
 

cvhu

Member
Jan 18, 2012
97
sarnia, ontario, canada
my pcm is a 2001 and has been programmed for my gear and tire size, the aveo speedo is of by 10 to 12 km's with the vss wire straight from the pcm, thats why i am trying the vssb
 

supwicha

Veteran Member
Feb 23, 2014
185
Victorville, CA
cvhu said:
my pcm is a 2001 and has been programmed for my gear and tire size, the aveo speedo is of by 10 to 12 km's with the vss wire straight from the pcm, thats why i am trying the vssb

Seems like that will work. Question: is it off by 10 at all speeds or is it less at low speeds and gradually gets to 10 at higher speeds?
 

supwicha

Veteran Member
Feb 23, 2014
185
Victorville, CA
cvhu said:
its off from start to stop by 10 kms, could you share with me how you were able to reset the odometer read on the aveo cluster

I don't have an exact procedure, I stumbled on it by mistake. I'll try to replicate and give you an exact procedure, but basically I had applied power to the ignition circuit on the cluster but not on the battery circuit while holding the trip button . A prompt appeared that said "erase?", I pressed the trip again and it set it to zero. After applying power again, it was showing zero.

I'll try it again and see what I can come up with.
 
Last edited:

paintman65

Veteran Member
Jan 8, 2012
186
Brenham TX
supwicha said:
To be truthful, it is a work in progress but looks to be hopeful. Just in case you need the information:

PCM (Powertrain Control Module - Computer)

VSS (Vehilce Speed Sensor - Located in the tail of the transmission)

VSSB (Vehilce Speed Sensor Buffer - Used to calibrate the speedometer without changes to the PCM - FYI I'm not using this)

As far as parts go, I used all of the factory gauges from my '78 Camaro except for the speedometer.

For the tachometer signal, I picked up this from pin A13 from my PCM rather than the coil. The coil works as well but requires a filter for noise.

For the speedometer, I used a cluster from a 2005 Chevrolet Aveo (Ebay $18 free shipping) - (I think '04 to '08 are the same). You will need to use the original circuit board that comes with the cluster. You will need to unsolder the gauge "motors" from the circuit board.

You will take the speed signal from your computer and wire it to the circuit board of the aveo. You will have some wiring from the circuit board of the aveo to the speedometer that you modify and fit in your cluster.

I know this is not very good detail, once I get it all ironed out and verified functional, I'll do a detailed step by step tutorial.

Hey supwicha did you ever get this all worked out. I'm thinking of doing the same thing in my '81.
 

supwicha

Veteran Member
Feb 23, 2014
185
Victorville, CA
paintman65 said:
Hey supwicha did you ever get this all worked out. I'm thinking of doing the same thing in my '81.

Been busy working on other parts of the car, I've been putting this off. I'll be getting back on the cluster soon. I've put it off because I would like to use a connector to isolate the PCB from the donor vehicle rather than hard wire and solder it. I just need to get off my can and get back on it. The good news is that I swapped the caprice axle so the engine/trans/differential are all together with the matching PCM calibration. That way I'll know if other calibrations will be required to make it work. Stay tuned. . .
 

paintman65

Veteran Member
Jan 8, 2012
186
Brenham TX
Thanks. I finally have all the mechanical aspects of my swap done, just need to finish up gauges. Would love to use Speedhut or Dakota Digital but not in the budget right now. Besides I like the satisfaction of using a factory piece and not just throwing money at stuff.
 




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