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After driving around with my ScanGauge for a while I have come to the conclusion that there is way too much going on in the cockpit for my liking. Digital speedo, MFD for energy flow, ScanGauge for engine status, and...oh, hold up, is that a road out there? Time to simplify!

As much as the ScanGauge can give me all kinds of information, you just can't beat analogue feedback for the essentials. So today I picked up a small, inexpensive analogue tach from AutoZone. Hobbit has already proven that it can be done, so it's not like I'm breaking any new ground here.

So far I have tapped into the IGF wire of the ECU to get an ignition signal. I found that information here:

http://www.vfaq.net/proj-pics/vent_panel/04_TachECM.gif

I have also managed a temporary mount of corrugated plastic to hold the unit in the tiny window off to the left, with the wires disappearing behind the trim.

Next up is power, ground, and the illumination wire. If I can figure out how to get to it, I know that there is an illumination wire here:

http://www.vfaq.net/proj-pics/vent_panel/tach-illum-01.jpg

I think that group of wires lives behind the trim panel to the right of the radio but have yet to venture back there. I'm probably just going to get power and ground by tapping into the accessory outlet because I can't really find anything else that a) I can get at easily and b) I know won't deploy my airbags if messed with.

Once all is said and done I will have reduced the essential gauge sweep to just two stops: the speedo and the tach. I'll know if the engine is running or not and I'll know how fast it's going. Between that and my accelerator position I should be able to be reasonably sure of the drivetrain's state. (I think I read that the tach will drop to zero during warp-stealth, too, which would complete the package.) Instant fuel economy could be checked, but I have a feeling that it becomes redundant since engine RPM seems so closely tied to power output.

So we'll see how it goes. This could be a big improvement to my driving environment once I get it working.

I totally agree that an RPM gauge is a necessary gauge in our Priuses. In fact, I missed it so much that I got me a scangauge. Still, I agree. It would be nice to reduce the information clutter to a simple critical set of good looking gauges where the RPM happens to be one of them. I still find the SG looks out of place.

I am however reluctant to tamper with the visible trim. Heck, I already have some scratches on the dash trim without even trying. I can just Imagine if I did - my wife would kill me ! ;)

Can you post some pics of your progress whenever you get a chance?


Cheers;

MSantos

Heh. My rule about cars is "It isn't mine until I have added something and broken at least one trim fastener in the process." I guess it isn't quite mine yet because, despite my best efforts, all of the trim has gone right back from whence it came. Toyota seems to use a much more resilliant type of fastener than I'm used to and the panels are flexible enough to be twisted a bit without incurring any damage.

Anyway, I have success and yes I will post pics as soon as possible. The current state of things is entirely embarassing, with the tachometer sitting cockeyed on its piece of corrugated plastic and wires connected by alligator clips running every which way. But it does do its job quite handily. When fuel is being burned the tach is indicating. When fuel is not being burned the tach drops to zero. It's interesting because it definitely confirms that there is zero fuel consumption during warp-stealth.

The only thing I have failed to do (aside from buy more crimp connectors and put away the wiring) is attach the illumination wire to a proper source. Power and ground come from the passenger-side accessory port and the illumination wire runs directly to the same switched 12V source. It isn't perfect but it does the job.

Hi Tim:

___Although I do not know how much customization can be done with CAN-View, the screen I saw at last weekends Hybrid fest looked ripe for customization. See below. There are a number of laptop OBD-II solutions that you can configure analog dial gauges for everything but a TC - FCD but there goes your SG-II? I wonder if you could dual tap the port?

http://www.cleanmpg.com/photos/data/515/Can-View_in_the_Prius_II.jpg
http://www.cleanmpg.com/photos/data/515/Can-View_Open_View_in_the_Prius_II.jpg

___Good Luck

___Wayne

Hey, sorry I didn't reply to the PMs or comment on al this yet;
I was WAY busy with Arisia (http://www.arisia.org/) this weekend and totally not keeping
up with forum-reading. Congrats on getting the thing working,
and I'll bet your dash looks like mine did for the entire first
summer of ownership as I kept the "research environment" up for
more discoveries.
.
My "power windows enable (http://techno-fandom.org/~hobbit/cars/pwe/)" article shows tapping a wire from the
dash-lights rheostat to enable the power windows with the light
switch. That gray wire shown in "theplan.jpg" is the ILL+ line,
which is fed +12V when the parking lights go on. So it would
be easy and totally nondestructive to tap there instead of messing
with that huge block of stuff over on the right. Something to
think about if you want to rework what you already did..
.
A slight correction -- the fact that the tach drops to zero in
warp-stealth doesn't prove non-injection. It proves that spark
has ceased, since IGF is feedback from the ignitors. It *implies*
that injection has ceased since it wouldn't make much sense to
inject fuel and then not burn it... but direct electrical proof
of closed injectors comes from the "squirt" light, not IGF.
.
Anyways, yeah, if I ever finish the final bit of that trip report
it'll have lots of poop about RPM ranges to play with...
.
_H*

CAN View is the ultimate solution, no doubt. One thing I desperately want is the ability to log vast quantities of data and analyze the crap out of it...I love data. I think that the laptop solution would be the most likely at the moment from a cost point of view, although it would preclude continous acquisition from day to day. (Not that it's necessary in the first place, of course.)

Alas CAN View requires a substantial cash outlay, and my Sunpro tach cost me all of $37 and what would have been a little sweat if it were warm enough for sweating. The high-tech stuff will come but for now it's all about letting the FE come to me, as you have said before. Listen to the vitals, pay attention to what the FCDs do from day to day, and pray for spring to come early so that I can enjoy some truly disgusting numbers :D . (I hope I can back-up that big talk.)

Anyway, I found my way to a RadioShack today and found the necessary connectors in what's left of their components section. (Sad that the selection of small electronic parts gets smaller and smaller because that's the only reason I have ever gone to RS.) The wiring is solid and working, and in a few moments i'm headed out to tuck away the last bits of wire and add a shim or two to my temporary mount.

Today's driving went extremely well with the new gauge. At this point I can pretty much keep the aFCD displayed while using the tach plus seat-of-the-pants feedback to figure out what the drivetrain is doing. I like it! There is just one tricky situation, which is gliding with a high SOC. Under that condition the point at which the electric motor provides boost seems to creep up on the glide spot. It's not too tough to get into mild assist by accident so it will be important to keep the pedal **just** below regen.

We'll see what happens. Eventually. (With sub-freezing temps for the foreseeable future there will be no records set on my end.)

**EDIT**

Hobbit, thanks for the info about the rheostat. I may play with that when it warms up a bit. And yes, you're right about IGF only impying non-injection of fuel. I just can't think of any situation under which passing raw fuel through the exhaust valves would be a good idea so, well, you know what I meant ;) .