Replace your factory Passkey II module.
When upgrading your stock Fiero engine using the 3800 computer, this module is the one-step answer to replacing your factory Passkey II module. This is the only module you will need to allow your engine to start and make your Fiero speedometer work properly. (The speedometer output from the 3800 computer is not compatible with the input to the Fiero speedometer). This module resolves this problem. On 4 or 5 speed stick models, the speedometer portion of this module is not used.