Hello everyone I'm trying to get my speedometer fixed after 6 years of not having one it quit working when I removed the ecm when I put the carb on it is there anyway I can get it to work without putting a computer back into it?? Any help or insight would be greatly appreciated

 

It has to have the ecm. Why did you pull it just to put a carb on? Are you running manual guages for temp and oil pressure?

 

Never had a problem with the temp and the oil pressure I pulled the ecm when I put the carb on because at the time that was the third ecm the truck had eaten so I pulled it and tossed it in the trash..the oil pressure and temp senders I had to rewire to work without the ecm I was wondering if I could do the same with the speedo

 

Well hopefully someone will post some better info for you. I've only done the carb swap with the ecm intact. I don't see why the vss couldn't bypass the ecm.

All my trucks are 4x4 so I'm not sure if the vss on a 4l60 could be swapped with a mechanical system off a old 700r4 with a mechanical speedo. Might be something to look into as well.

 

Thats a toughie. The ECM computes the speedometer pulses and translates it into the dash. As a certified mechanic since 1970, I am puzzled why your ECM's supposedly went bad. Fairly rare for a ECM to actually fail. Most in the field are returned to repair facilities where they don't find anything wrong with just the ECM. Ecm's have battery+ voltage inputs and grounds that should be tested before determining that the ECM failed. A engine lasts much longer and runs much better with an ECM than a carburetor. Better gas mileage and etc. However for the novice, carbs are a lot easier to deal with. A good wiring diagram is critical to troubleshooting why an ecm doesn't function.

 

BTW, the vss sends an ac frequency signal to the ECM. The signal coming out of the ECM is a digital pulse signal that the ECM sends to the Speedometer display. I believe that the ECM signal is different than the signal it receives from the VSS, but don't know the exact form.