2 pcms? (Page 2/2) fieroguru JUN 10, 01:26 PM quote Originally posted by reinhart: This is the correct answer. The only thing that you might have issues with is the Fiero speedometer. You might have to get a VSS converter, but none of the other sensors on the Fiero dash should have a problem with swapping out the ECM. If using a stock Fiero transmission, then the VSS already goes directly to the speedo and the speedo output goes to the ecm. When swapping in another engine, you can T off the VSS wires to send the signal to the ecm while the speedo continues to get the signal from the stock VSS. If you swap in a newer transmission with a different style VSS, then routing it through the ECM so it can be calibrated is the best method. Most of these will need the booster circuit on the ECM output to the speedo. olejoedad JUN 10, 07:50 PM quote Originally posted by sanderson231: True but I've always heard that the square wave output of the 3800 PCM needs to be converted to a sine wave for the Fiero speedometer module. So that's what I have done on both a 3800 and 4.9L swap. The circuitry is simple and consists of two resistors and a capacitor. You can build it yourself or one can be bought for $22: https://reddevilriver.com/h...peedo-buffer-circuit This is correct, I've built several over the years.