Hi guys could use some more help. Still trying to finish up a 4.9 swap in an 84se. My current problem is the speedometer not working, I bought a conversion module from fiero addiction when putting it in I found that there was no wire in space g on c203 and no yellow wire anywhere on c203. Looking at schematics and the old engine harness it appears that the old vss went to the ecm then to the cruise and speedometer with a brown wire. I tried putting the module on the brown wire still doesnt work.

There are two problems...

One is that All Fieros have the VSS go to the speedometer first and then to the ECM. If you changed to a 4.9 do you have the 4t60e transmission too?

If so then the normal (for a Fiero) order is reversed and the VSS goes to the Caddy ECM directly and the Fiero addiction (rockcrawl) circuit goes on the VSS output of the Caddy ECM (pin 11 or 12 - there are two redundant feeds) of the smaller connector.

The second problem is that the 84 Fiero is wired different that the rest. On a stock 84 the speed sensor is going from C500 directly to the speedometer and then from the speedometer to the Fiero ECM through C203. On a 4.9 conversion that C203 is going to be dead because nothing is going through it.

What you want to do is take the signal from the rockcrawl circuit referenced earlier and feed it to the VSS hi directly on the cluster (c204) at pin S, (the yellow wire)

[This message has been edited by jscott1 (edited 04-19-2008).]

jscott1 Thanks for the info. Can I feed the speedometer from the rockcrawl circuit through the wire from c500 (if so which one) or do I need to run a new wire up to the cluster?

quote Originally posted by milkman: jscott1 Thanks for the info. Can I feed the speedometer from the rockcrawl circuit through the wire from c500 (if so which one) or do I need to run a new wire up to the cluster?

That would work also... (it's B1 on C500)

I thought about telling you to do it that way, but if I were doing it I would just run it straight to the cluster...less chance of making a mistake in the wiring.

jscott1 thanks again!! speedometer is working fine. btw Iinstalled a set of gauges from Toms digital electronics. They look real nice. I would reccomend them.

quote Originally posted by milkman: jscott1 thanks again!! speedometer is working fine.

You're welcome. It's was your lucky day, I just happen to know a bit about the 84 and 4.9 speedometer wiring