93-97 Coolant Temperature Gauge Modification

[94landcruiser]

I took the truck to Toy Specialists today, we confirmed using the OBD2 computer that these numbers using 110/50 resistors are correct:
Pegged hot 244°
Top of red is 227°
Bottom of red 217°
Center is approximately 189°
Cold line is 160°
Pegged cold 150°

We ran the computer out the hood, into the truck and I drove around. within a degree the figures are accurate.

My truck runs just fine and I have a usable temp gauge thanks to you guys.

THANKS!

 

[Miescha]

I'm definately going to have to do the temp gauge mod!

94landcruiser: How did you get your truck hot enough to confirm the two top-end numbers? Wouldn't the t-stat kick in and cool it off before then? What am I missing?

 

[94landcruiser]

I verified the mid range 189-203 it was as listed on my gauge. It was over 100 ambient at the time so colder was impossible and obviously I did not overheat my engine. I am assuming that since the range I was running at was accurate it will remain accurate.

 

[semlin]

I took the truck to Toy Specialists today, we confirmed using the OBD2 computer that these numbers using 110/50 resistors are correct:
Pegged hot 244°
Top of red is 227°
Bottom of red 217°
Center is approximately 189°
Cold line is 160°
Pegged cold 150°

We ran the computer out the hood, into the truck and I drove around. within a degree the figures are accurate.

My truck runs just fine and I have a usable temp gauge thanks to you guys.

THANKS!

obd2?? you got a special 94 lc or do you need an updated sigline?

 

[94landcruiser]

He used this:

 

[94landcruiser]

My truck is a 94 he said this updates much more slowly and does much less than on obd2 but this will give basic sensor data like temp & 02 sensor mixture states.

 

[semlin]

cool. that's an aftermarket obd1 scanner with full function obd1 instead of just code reading. i have never figured out what those old obd1 scanners can do and I didn't know even the toyota ones could do temperature. I would be very interested in knowing what else it can do for obd1.

 

[94landcruiser]

I'll be happy to ask him.

 

[sandcruiser]

excited to be what looks like the first diesel to try this out
getting red at 217 sounds perfect for me. It's hot here, I don't want to push it.
I plan to add an analog guage anyway, eventually, but even then I want something to indicate to other drivers if there is a problem.... and now I can mount the analog much lower/out of easy viewing without being worried.

Now if I could just get my stock oil pressure guage to work....

 

[semlin]

excited to be what looks like the first diesel to try this out
getting red at 217 sounds perfect for me. It's hot here, I don't want to push it.
I plan to add an analog guage anyway, eventually, but even then I want something to indicate to other drivers if there is a problem.... and now I can mount the analog much lower/out of easy viewing without being worried.

Now if I could just get my stock oil pressure guage to work....

post pics before the mod. I'd be interested to see how close a match it is.

 

[sandcruiser]

I've got this one

doesn't show the whole inst cluster, but the side that matters for this mod. Will snap more pics when I pull it out and get it open (after my resistors show up).

here's one of the front of the cluster- for reference's sake:

 

[RavenTai]

The screw pattern for the temp/oil gauge looks different than my 96, might be the same as the 93 though.

The connectors to the cluster look different also, where you have 3 on that side I have 2 large ones,

The real interesting part will to be to see the gauge itself,

Make sure you save your old parts are in reusable condition in case something is not the same (such as the sender calibration )

Assuming you have a zener diode make especially sure you note its polarity.

Personally first I would acquire a proper sender for your motor and see if it has the same temperature/resistance curve as the 1FZ if that is correct and the gauge is wired the same than the mod may work, I dont know one way or another.

 

[semlin]

I've got this one

doesn't show the whole inst cluster, but the side that matters for this mod. Will snap more pics when I pull it out and get it open (after my resistors show up).

here's one of the front of the cluster- for reference's sake:

were you running the engine with the steering wheel removed or is your temp gauge stuck?

it also looks as if none of your centre vertical row of lights are active and a plastic filler goes in there in place of module. Those are all for the auto tranny so I assume you have a manual transmission?

 

[sandcruiser]

Yes, motor was running.
I was fiddling around in there trying to get all the various dash dummy lights working, but mostly was trying to get the tach to work. Eventually I got the tach working (yes!) but not yet in this iteration.
You can also see that I still haven't gotten the oil pressure working. Maybe never will.... I'm adding an aftermarket analog guage anyway.... but I just like to have all the guages at least "sorta" working.

If you know you are pulling the cluster out and putting it back, pulling the steering wheel makes things sooooo much easier. I think. That is- I didn't even try it with the steering wheel in as I learned early on on my 60 that pulling the wheel only take a minute and saves many minutes of frustration with the dash/combo meter.

M/T. No center lights at all.

I'll ask around to see if anyone can source the part number for the temp sender. I'm hoping that Toyota used the same part, seems like a possibility.

 

[semlin]

your oil pressure sensor may just be disconnected near where the sensor mounts on the motor. On the 1fzfe it uses a very small plastic connector to the harness that is easily disconnected by accident when you are futzing around in that area.

 

[semlin]

there are pictures of my temp sensor from a 93 earlier in this thread. I also have a spare in the basement somewhere so if you pull yours post photos or any p/n#s and I can compare.

 

[RavenTai]

there are a lot of markings on the temp senders more than just a logo pand part number, has to be some data in there, not sure what they mean but would be interesting to see if any of the marking line up with the diesel sender






https://forum.ih8mud.com/showpost.php?p=653221&postcount=118

"I pulled the thermistor out of what I think is suppose to be a 95 head......................


The one I have from the spare head has markings on each of its 6 flats, it is the only water temp sensor that has only one pin on its connector.

Starting with "A" within a circle.
The next looks like an odd lower case "r" in a circle,
"ND" within a circle, NipponDenso’s logo IIRC
"205",
"29",
And the last flat "10N" ...........................

I briefly tried to make sense of the markins, maybe relating to temprature range or resistance but did not get far, I have heard of thermistors sometimes called 10K for 10,000 ohms, dont know if that relates to the 10N"

 

[sandcruiser]

More data (but not necessarily any help)
in the 1990 80-series chassis/body FSM it only refers to two types of temp guages one w/ Tach one w/o Tach. It is on page BE-61 for those with the manual and says:

IGN-Sender: 71-79
IGN-Grnd: 117-141
Grnd- Sender: 185-215

Now, that is talking about the screws on the back of the combo meter, not the actual Sender, actual GRND and actual IGN.

The rest of the manual deals with the 3FE, 1hz and 1hd-t.... so I'm inclined to believe that it is the same.

HOWEVER! As if life wasn't complicated enough... let's keep in mind that my motor is a '93 and the combo-meter came out of a 199? vehicle, possibly the same one as the motor, possibly some other vehicle. So I'm not sure how relevant the above info is to the actual situation.

 

[sandcruiser]

as for the oil pressure sender-- I've run the wire directly to the sender from the harness, I think. I'll have to reconfirm. Also have to test the sender. It is pretty tough to get at where it is located on my truck, both the oil filter and the brake lines sorta block viewing and reaching access to it. I may have simply failed to connect the wire to the sender very well... the wiring harness isn't stock there, so maybe the connector is simply not getting a good contact. Or maybe the sender is pooched. Or maybe the guage is pooched. So many fun and exciting potential problems!

Now if it would just stop raining, I'd get out there and try to figure out what's up.

 

[sandcruiser]

also-- not too keen on pulling the temp sender out at this point as the 80 is my DD.

When my wife gets back from the states with my OME suspension, my resistors, and various and sundry other parts from various Mudders.... the 80 will be out of commission for several days while all this stuff starts getting assembled/fixed/attached/mcGyvered.

At that point, I'll pull the thermistor if it makes sense to do so. Probably late Oct/early Nov.