Dash temperature gauge problems

[joegri]

hi fellas my temp gauge stopped working today and of all the gauges we have we need this 1 the most. i checked the fuse ok i just dont know where to go from here. i looked for power at the sensor(goose neck) area the brown connector no power there. with key on . am i getting close. tomorrow i,m gonna strip back the connectors and have a peak , unless you think i,m looking in the wrong area. aarhhhh seems everyday this week something has bitten me in the butt with this van. o well just cryin thats all but i could use a suggestion or 2. thanx guys.i know its just another situation that must be fixed!!!!

[timsrv]

Disconnect the sending unit and ground out the wire to the block. When you turn on the key to "run" the gauge should max out on hot (don't leave it like that for longer than necessary because the gauge isn't designed for a prolonged short here). If the gauge jumps up with the sender wire shorted then the sending unit is bad. If it doesn't affect anything then it's a bad gauge or a wiring problem. The gauge can be tested for resistance but the cluster needs to be removed 1st. This test will vary depending on what gauge configuration your van has. The BE section in the manual covers this test and all the variables. Of course there could be something wrong with the circuit, but the most common fault is with the sending unit. Tim

[joegri]

well i went to thr store this mornin and the gauge worked but only a lil i mean it raised up a quarter inch or so ???? i guessint that the sensor is starting to fail ... maybe thanx again tim for the hint / direction to go

[Chester]

After reading all the posts I figured out that my thermostat was bad. Water temp gauge on the dash started below C and would only go to the top of the C. Got a new thermostat and now the water temp gauge on the dash goes above the C and to about half way when I am driving. Only problem is once it gets slightly above the C if I hit a bump the needle dances up and down about 2 to 3 mm. Really rough roads look really exciting. Any ideas to fix or should I just get used to a dancing water temp needle on rough roads?

[timsrv]

The gauges themselves are supposed to dampen movement of the needle. This makes response a bit slow, but keeps things steady. Since the values they're displaying typically take a while to change it all works out. If you have a gauge with a bouncy needle, especially one that bounces due to external vibrations, that means the gauge head itself is to blame. I'd keep a lookout in the salvage yards and snatch the next one that comes along. These did vary with trim levels and changed throughout the years, so finding the exact one might take a while. There are also a couple different manufacturers Toyota used for these too. Not sure if Toyota even sells these anymore, but if they do, I'm guessing they'd want it's weight in gold. Another option is to put an aftermarket gauge unit in. These don't mount as nicely as the factory gauges, but they are usually more accurate and display actual temps instead of approximations. Good luck. Tim

[Chester]

So can I pop out the water temperature gauge from the back of the speedometer odometer cluster or do I just find a new speedometer odometer
cluster and plug it in? I am getting used to the dancing. Additionally, my heater temperature is much better now ( after changing the thermostat).

[timsrv]

If you find the same cluster you can go either way. If you're concerned about the correct miles displaying, I'd probably just swap the gauge. Tim

[ToyotaVanNut]

Hello,

So first a very small backstory, which I believe has nothing to do with the current problem but, I want to disclose all information:
I went on a trip to Texas, everything running perfectly with the van. I got the oil changed at a Walmart, and noticed that they created an oil leak from the oil pan (I am assuming they did not put on that washer correctly or something like that). The leak was very minor, I just would check the oil daily and fill up when needed.
When I got home to California, I went to get it changed again (went to Walmart thinking they might discount it due to the previous error, no such luck). I told them about the oil leak and they said they fixed it. They didn't. The leak was worse than ever (losing about 1/4 a quart every day). I have just been checking a filling regularly while I sort everything out with them. I have been mixing oils, (I usually use 10W-30, but have used 10W-40 and 5W-30, anything I can find laying around rather than going to buy more) and I was told this will not harm the engine. Also, the battery in the van is on its last legs (it takes a few gas pedal pushes to get the engine to turn on).

Current problem: I was driving last Saturday, running errands, everything normal. But after about 3 hours of doing this (not consecutive driving, would drive maybe 30 minutes, stop for an hour, 45 minutes, go into a store for an hour, etc.) But then I noticed as I turned on the van and was getting my seatbelt on and all of that, that the temperature gauge was up very high, almost touching the top end of the "white" bar. I was very scared, but thought "how could it get this hot in a few minutes after being parked for an hour?"
I checked the oil and coolant levels, everything basically normal. I drove home (~45 minutes) basically the whole time with the temperature gauge in the scorching red!! The temperature gauge was touching the red, but, I noticed nothing different and just drove it home. Luckily, the engine is not melted and the van runs and turns on properly.
Just now, I checked on the oil, and turned it on. In a matter of about 10 seconds, the temperature gauge was at the top of the white bar again. This is after being parked for almost a week, on a cool night! Now, I may be wrong, but I do not even think it is physically possible for it to get that hot within 10 seconds of turning on the engine, right? :dizzy:

What is the problem? Is the temperature gauge broken? Or is it really getting close to the red hot bar in a matter of 10 seconds?

Any help is so greatly appreciated.

Yours,
TVN :no:

[timsrv]

No, it's not possible. Even if you had no water in the engine, it would take at least 5 - 10 minutes of running to get this hot. It could be the gauge head, but I doubt it. Most likely it's a bad temp sending unit (on the head) or a shorted wire between it and the gauge. To check the sender pull the wire from it and use an ohm meter to check resistance between the terminal & ground. On a cold engine you should see 250 ohms or more. If it's the culprit, i would expect to see around 25 ohms (to explain the gauge reading). Most likely cause is the wire between the sender & the gauge becoming chafed/shorted. If it's the wire, these type problems can be hard to track down. I'll usually just pull a new wire than to mess with tracking down the trouble spot. Good luck. Tim

[ToyotaVanNut]

Tim,

Thank you so much. You seriously do not know the level of gratitude I have towards you not only in your knowledge but in the swiftness of your responses.

Thank you again.

[ToyotaVanNut]

I am trying to buy a temperature sending unit, but which would fit a 1985 Toyota Van RWD?

Is it this one?: http://www.partsgeek.com/gbproducts/WC/8202-01080775.html?utm_content=YN&utm_term=1986-1989+Toyota+Van+Water+Temperature+Sensor+NTC+86-89+Toyota+Water+Temperature+Sensor+1988+1987&utm_source=google&utm_medium=ff&utm_campaign=PartsGeek+Google+Base&gclid=CLSY2peUlL4CFcOBfgodezYAZQ

And how come they range from $20 to $100? I tried searching for Toyota Genuine Parts but the site did not have the temperature sending unit on it?

[timsrv]

No, the one in your link is the sensor (for the ECU). You need the sender. On that site it's this one: http://www.partsgeek.com/catalog/1985/toyota/van/body_electrical/engine_coolant_temperature_switch.html

The Toyota part number for this is 83420-20020

[ToyotaVanNut]

Thank you so much! I am ordering this now!

[ToyotaVanNut]

1557

Hi again Tim, I'm sorry.

1 - ?
2 - Overflow hose
3 - ?
4 - ?

But I am replacing 4, right? The person I am working with to fix the van asked me to ask again to make sure with part 83420-20020 that that is the part that goes to the temperature sensor, and which of these 4 to pull. I know it is not #2!

I told him, it is the SENDER, part 83420-20020, like Mr. Tim said, and it goes into part 4. Am I correct? He thinks its the previous link I mentioned into part 3: http://www.partsgeek.com/gbproducts/WC/8202-01080775.html?utm_content=YN&utm_term=1986-1989+Toyota+Van+Water+Temperature+Sensor+NTC+86-89+Toyota+Water+Temperature+Sensor+1988+1987&utm_source=google&utm_medium=ff&utm_campaign=PartsGeek+Google+Base&gclid=CLSY2peUlL4CFcOBfgodezYAZQ

Can I prove him wrong?! :wnk:

Thank you so so much!

[timsrv]

#1= Temperature Switch (closes at 230 deg F). ECU monitors this on start-up. If switch is closed then ECU activates "pressure-up" VSV for 2 minutes (to help combat heat soak).

#2= Overflow hose

#3= Cold Start Injector Time Switch (for activating cold start injector).

#4= Temperature sensor for ECU. This is a thermistor (resistor that changes value as temperature changes). ECU monitors this & calculates fuel mix ratios based on resistance.


The sender for the temperature gauge is on the passenger side of the head in front of #1 spark plug. You'll need to remove the passenger seat & the access panel to get a good look at it. Here's a picture:

http://i8.photobucket.com/albums/a23/timsrv/CoolantTempSender.jpg

[ToyotaVanNut]

Hello,

I am trying to replace to temperature sender, where I will replace it. I have the part, I took out the seat, I just don't know how to access it. Am I looking in the right spots? Can I see it from underneath?
This is in reference to my last post: http://www.toyotavantech.com/forum/showthread.php?1878-Temperature-Gauge-Problem

Thank you kindly :pissed:

1659166016611662166316641658

[timsrv]

http://i8.photobucket.com/albums/a23/timsrv/IMG_3369_zps62e90a99.jpg

http://i8.photobucket.com/albums/a23/timsrv/IMG_3370_zps44423191.jpg

It's Toyota part #83420-20020

For organization reasons I merged your new thread with your old. Tim

[ToyotaVanNut]

Tim, my gratitude knows no bounds. Thank you so very much, this is immensely helpful :)

[ToyotaVanNut]

Tim, problem SOLVED!!!!!!!!!! This was EXACTLY it and the van is back up and running perfectly!

[timsrv]

:dance1: :thmbup:

[Black Pearl]

thanks for this link Tim.
Also, the wiring on my van is very old and brittle. The female plug cap for the sending unit disintegrated when unplugging it.
I am having a time finding a new cap to solder on. Do you have any suggestions? Someone at Napa said to just solder on a spade head. I am not sure I like that idea. but will go with it if I can't get the proper plug.

[timsrv]

It's just a 1/4" male spade post on the sender. A 1/4" female spade is all Toyota uses for the harness, it's just the insulation part that's different. I wouldn't hesitate to use a standard spade here. The insulation part on most of my vans has deteriorated, but as long as the conductor part is intact, I keep using the factory harness connector. If you really want a factory type connector here, you could probably go to a salvage yard and cut one off multiple places on many different makes/models, then solder/shrink tube. Tim

[brentlehr]

Hey everyone. I searched for a while but couldn't find what I'm looking for. I recently bought an 86 LE 2wd. Had a code 4 so I replaced the water temp sensor while doing a basic tune-up. Van runs great but now the temp gauge on the dash isn't working. Checked for loose connections that I might have bumped as well as all of the fuses. Everything looks okay. No codes either. Is there another water temp sensor I'm missing?

[brentlehr]

Okay, resolved this issue. I took the passenger access panel back off and inspected very closely. The temp sensor in the block (1 wire) and it's connector looked good. I cut away some of the heat shrink and found part of the wire exposed from a crack in the insulation. Clipped the wire back, installed be end, re-connected the wire and we're in business.

Guess the years under the hood can cause all kinds of electrical gremlins. Just glad this one was simple.

[tennesseetoyota]

http://i8.photobucket.com/albums/a23/timsrv/IMG_3369_zps62e90a99.jpg

http://i8.photobucket.com/albums/a23/timsrv/IMG_3370_zps44423191.jpg

It's Toyota part #83420-20020

For organization reasons I merged your new thread with your old. Tim

Tim, appreciate the detail here as always. Do you happen to know what the plug below the sender unit is? After a similar debacle with my temperature gauge I realized that not only was it unplugged, but the unit on the block that the plug itself plugs into is missing (so I cannot plug it back in). Would this explain why my temp gauge is not functioning? Thanks in advance.

[timsrv]

Search the site using the term "water thermo switch". It's to delay the overdrive from kicking in on vans with automatic transmissions.