Since I installed my OHC, I've noticed that the temperature updating has been hit-and-miss. Sometimes it will rise with air temperature, most of the time it won't. Recently, I bought a Ford H/U with speed volume. Spliced that into the VSS wire, made sure the connection was good, and found that speed volume isn't working. I read somewhere that Ford changed the VSS scheme between 1997 and 1998, and that parts from the two "eras" aren't compatible (eg: OHC from 1998+ won't read the VSS in a 1997 truck). Can any electrical gurus here confirm that this is true? Perhaps the gray/black wire behind my radio is in fact NOT VSS after all?

 

I'm not an electricul guru by any means, but I can tell you that your '97 has a VSS signal that is carried throughout the truck by way of the GY/BK wire, including to the GEM. Is it possible you tapped into the wrong wire? There are quite a few back there, sometimes a couple can get to looking alike.

The GY/BK wire leads to pin #9 in one of the GEM harness connectors (which puts it on a "corner").

For the purposes of the OHC and SSV mods, there is no substantive difference between the VSS signal on a '97 and the VSS signal on newer models.

 

That's the wire I've tapped into. I've made sure time and time again that it's got a good connection (read good continuity with power off), it's starting to bug me.

 

dude, me too. i can't get the temp to work right.

 

My OHC came from a 98+ explorer I'm pretty sure. It works just fine for me. It sounds like you may have the wrong wire. The OHC needs a signal from the vss to let the temp go up. That way engine heat won't raise the temp when you stop for a while.

 

I'm 99% sure I have the correct wire. I will snap a picture after I get home from work tomorrow. (Finally got me a digital camera!)

 

the temp sensor itself could be going bad!

but, i say wait around for either John or Bob to chime in with a deeply profound statement of what exactly is wrong, why it's wrong and how you can fix it...

those two never cease to amaze me with the extent of their electrical knowledge!!!