16 Jul 2021
Things Were Done Wrong

That'd be a good alternate title for the website: "Things that I have done that are probably done incorrectly".

Realized last time that I don't have a wire for the tach, also that I don't have the "you're in cruise" wire (referenced halfway down here)

Well, the wiring diagrams helped; they let me know that the tach wire goes from the PCM as circuit 121, Red #10 not to the dash -- that comes over the serial data - but to the traction control (which I don't have), and that the "cruise active" wire is PCM circuit 85, going to pin Red #13.  Both wires are white and are pins F and G in connector C105.
Well, we have to start by removing this fender.  I'll have to do some cleanup to try to get it to fit better anyway.
Here we have C105.  I only have one of these wires - the tach wire to the traction control.
So I can just remove it from C105, go from the PCM directly to a wire heading into the cab.

I tried a weatherpak connector and made what looked like outstanding crimps.  They weren't outstanding; no continuity between the weatherpak pin and the PCM pin 10.  Also no continuity between it and PCM pin 13... and when I went to pull it back apart, the weatherpak pin just pulled right off.

And then I realized that what I had was not the tach wire, it was the cruise enable, and I'd cut the C105 pin off. 

So - where is the tach wire from the PCM going, and what am I going to do about the cruise-is-on light wire?

As it sits here, I have pin 10 of the PCM (Tach out) connected to apparently nothing, and pin 13 (Cruise Indicator in) (not really) connected to a wire headed towards the cab.  Quick fix: de-pin the PCM for both, so pin 10 is to the tach wire.
Back in the day ("The day" being defined as 12 Jun 2020), I put a grommet in the firewall and ran the wires for C220 and C230 through it.  I've since realized that low on the firewall on the pass side invites a flood every time I drive in the rain, that location is unsuitable. I'll need to run them through the cowl sides.  They're *probably* long enough.  I'll also run the two new wires for the tach and the cruise indicator.
You can vaguely see the grommet and the wires.
The better seal on the inside still wouldn't be sufficient.
Of course, as part of this, I had to unwrap the wires.  Again.  Really would have preferred to not do this.

Go back to the previous day (10 Jul 2021)