Using F-body Ecm W/5 Speed Conversion..., all in good except

[406Z26]

This is the deal.

After I did the 3x00 5 speed conversion I could never get it to idle correct after deceleration. Also there was an intermitent SES light for auto transmission DTC's.

So, I decided to use a '93-'95 Camaro 3.4 SFI ECM. It is the same one in our 3x00 equiped Berettas, well the service number is the same the programing is different.
All was good after adding a VATS module wired with resistors to match the key and removal of a few car side ECM pins.

First crank it started right up, ran great all the way through open/closed loop operation.

Then I took it for a road test....WTF! The damn speedo pegs out at 120mph in second gear! I looked at both pinouts and found this...

Vin M Beretta 3100 ECM...
Pin B28 Buffered Speed Out (4000 pulses per mile) On 8.8 volt Run 9.9 volt

Vin S Camaro 3.4 ECM...
Pin B28 Buffered Speed Out (4000 pulses per mile) On 9 volt Run 10 volt

Also both the VSS input high and low are the same to the T.

So what should I do to correct this? Or am I going to need to find a way to use a Camaro gauge cluster?

Any help would be great!

[brian89gp]

The problem is most likely not the output of the ECM or the guage cluster. The VSS pickup on the transmissions is most likely way different with way less pickup teeth on the Camaro transmission. Plug it into your FWD with more pickup teeth and you peg the speedo.

What you are looking for in the ECM is a "speed sensor constant" and a "pickups per mile" variable. Either that or purchase a speedo recalibrator that attaches to your VSS sensor.