so the other day i was trying to load a new tune onto my 97 formula (obd1 conversion) and while the upload was in process my laptop crashed an kill my cars pcm. well i got ahold of another pcm out of a 94 caprice with an L99 in it and i was able to load my cars old tune onto the new pcm. well now with the new pcm for some reason my tach isnt working like neddle not moving at all!

any of you guys have any ideas as to what could be causing this?? i though maybe because the pcm still thinks its a 94 caprice, should i change the vin over?

also for some reason the car is running alot hotter than usual, what could be causeing this??

 

anyone have any ideas? iv got an lt1 scanmaster that i have hooked in the serial port under the dash and its reading my rpms... wonder why the gauge isnt working???

 

The tach is driven off pin A13/white wire on the red connector on the PCM. Put a frequency meter on the wire at the dash end, and see if the PCM is sending a signal to the tach.

 

thanks for the help Injuneer, but where can i get this frequency meter from? also you know where i might be able to see pics of this said A13/white wire in the area im looking for to test it?

thanks again Injuneer

 

Most low $ multi-meters now include a frequency scale.

The white wire runs through connector C230. Shoebox has the connecto face diagrams for these connectors.

http://shbox.com/1/harness_connector_faces.htm

He also has the dash connector diagram for a 95. Not sure if your 97 is similar.

http://shbox.com/1/95_z_cluster_pinout.jpg