tach signal

Don't know if this will help, but here is a link to what little there is on
installing an after-market tach in a Gen II car:

http://techno-fandom.org/~hobbit/cars/tachack/

Have you considered getting a ScanGauge, it will give you RPMs and a
whole lot more and its plug-and-play as well: :cheer2:

PriusChat Shop : ScanGauge II Scan Tool + Digital Gauges + Trip Computers [ScanGaugeII] - $159.95

Unfortunately, the XGauge feature is inop on the Gen III at this time.
It took a number of years for folks to crack the Gen II codes, so there is
reason to believe that Gen III XGauges will be found sometime in the
indefinite future.

 

I agree with Rokeby, check out the ScanGaugeII.

When you set it up you tell it you have a hybrid and it indicates as long as the car is on even when the engine is off. I have mine set up to tell me coolant temp, ignition timing, and throttle position as well as RPM. There are several other parameters you can display (4 at a time) if you wish.

It is small and light and mounts nicely on the steering column with velcro. Total installation and set up time about 5 min.

 

Excellent!

I believe the engine control computer is located in the engine compartment. To tap a spark, injector or other signal, you'll need to run a data line (or signal) from the compartment into the cabin. Ken@Japan posted a note about tapping a signal this summer and that might be your best bet.

Do you have the instrument already? What make and model? What interfaces does it come with?

Bob Wilson

 

engine speed: #16 of A connector on the Power Management ECU shows the engine speed.
injector: we have to tap off from the injector drive wire, like shown following picture.

Ken@Japan

 

I know it's even more $$ than the Scanguage, but I was thinking that if anyone is looking for a more lifelike tach, the below product looks nice and might work... Like the SG, it connects to the OBDII plug.

WatchDog? Economy Monitor - 40400, 40402 - Gauge monitor with a Driving Coach to maximize fuel economy

No idea how well this would work with the GIII Prius, but I like the look of it.

 

The GI signal is 12V square wave as attached.
The PM ECU is located behind the glove box and the ECM is located at driver's side under the hood.
But, it's hard to access the ECM connectors because of the connector cover, so I tapped off from the injector connector.

Ken@Japan

 

risingsun,

Better look twice at the Bullydog unit. The only Toyota on their
applicable vehicle list is the Tundra.

For any multiple gauge display unit to work effectively on the Prius, it
has to have a "Hybrid" setting. This because the Prius ICE frequently
shuts down during vehicle operation. Without the hybrid setting the
gauge package starts and stops the mileage readings whenever the ICE
shuts down, making at least MPG and "average" readouts useless.

I think that I've looked into all the various currently available gauge
units mentioned here on PC. The only one that I know has the Hybrid
setting is the ScanGauge. It also has the very useful programmable
XGauge feature for displaying hybrid specific parameters, currently
working on the Gen II, but not the Gen III.