No temperature gauge in the Prius

it has always been my position that we should have the option to purchase additional capabilities as options especially ones that are as easy as CAN information.

i feel lucky that we have a motivated end user community with the skills to provide many things Toyota is not and i think that they are losing out on some good income. what we pay $500 or more for, Toyota probably could have provided for much less. and charged half as much and pocketed most of what we would have paid.

i simply feel that the Prius will go down in history as one of the most underestimated vehicles of all time. lets face it. it took Toyota most of 3 years to handle the demand of this car. i think they also underestimated the intelligence of the Prius owner and the fervor caused by the trinket of info they did provide. they gave us an inch, we liked it and now we want the rest of the mile.

 

<div class='quotetop'>QUOTE(hobbit @ Mar 4 2007, 09:53 PM) [snapback]400076[/snapback]</div>

I was planning on using mechanical Autometer gauges for the oil pressure and the coolant temperature. I can see right now the biggest PITA for me will be to rig up a Tee to retain the stock sensor, then kludge together adaptors to go from metric to English threads for the Autometer gauge.

On my 1984 Ford F-150 with 302 V8, it was remarkably easy for me to put Autometer temperature sensors on the Edelbrock aluminum manifold I installed in 1985. There were plenty of unused ports (Vacuum and coolant) for me to use, they were fitted with pipe plugs by Edelbrock.

For the temperature sender bulb at the front of the motor, I simply plumbed into the Ford factory pipe plug in the thermostat housing. Took around 10 mins, including draining coolant. The rear temp sender bulb I used one of the spare Edelbrock locations that had a pipe plug in it. Total time to put in both temp bulbs, including draining and refilling the coolant, was half an hour.

It's interesting when you drive around with that truck in -30 or colder weather. Even with a winter front, the rear temp bulb rarely leaves the bottom peg. The front temp bulb will usually track the thermostat opening.

In summer, when I've been working the truck, then shut it off, I can watch both temp gauges slowly rise due to heat soak. That is something a factory gauge is programmed NOT to do, it might "scare" the uninformed motorist. In +39 C weather my Ford block will eventually heat soak up to around 200 F on both Autometer gauges. This takes around 12 minutes. If I then restart, within 40 secs both gauges drop like a brick to lower values.

The oil pressure sender on the Ford was even easier. That year truck, Ford installed a 3 inch pipe with a threaded fitting on the end to accept the factory electric sender. I simply took the threaded fitting off, put a Tee on, and then installed both the factory sender and the Autometer pipe.

The only thing that worries me about working on the Prius is that I'll probably have to drain the block to get the factory sender out. That will probably become a very long and involved bleeding process.

 

A long list of Prius' temperatures are available but device such as CANview (2004+) and miniscanner (2001-2003) appear to be the best available readers.

Based on long experience with a 2001 I suggest that the most interesting temperatures are MG1 windings, and Tmax of the HV battery.

MG1 will get hotter than anything 'nearby' under summertime heavy load driving; my max was about 105 oC. Improved design in the new model Prius probably means less heat generated in the motor. Perhaps CANview people have posted reports?

When the battery Tmax gets above 45 oC I use maximum air conditioning and not in recirc. Cooling takes several minutes per degree, but heat is the NiMH killer, so it seems appropriate to take this extra step. Only seen traversing big mountains.

Recognizing that any temperature could get unruly under malfunction, these are the ones of routine interest. Engine coolant T is quite boring.

Jayman is doing yeoman's work in rigging up an oil pressure sender. Is is worth considering to just remove/replace the stock sender, and spoof its signal with some electronics? 'Closed' above 3 psi and 'open' below 1? I bet that is within Hobbit's reach for example.

If somebody built a buzzer circuit that would announce the low oil pressure light (suppressed during bootup), I'd buy it. A 'ding' and an MFD message is of course what Toyota should have done in the first place.

 

<div class='quotetop'>QUOTE(tochatihu @ Mar 6 2007, 11:11 AM) [snapback]400850[/snapback]</div>

I have to study the schematic. If I can get away with simply putting a fixed resistor across the connector, it would then be easiest to remove the oem sender altogether.

Something tells me it will turn into one of those major PITA situations which will lead to my heavy drinking. Or "heavier drinking" if you know what I mean