93-97 Coolant Temperature Gauge Modification (3 Viewers)

Joined
Oct 11, 2012
Messages
9
Yeah? Well grab some for me! Might be they are detecting my location as Aus because the 50 ohm will not let my buy less than 40. Just tried it again.
 
Joined
Sep 18, 2012
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Orem, UT
New part number for 50 ohm

Yeah? Well grab some for me! Might be they are detecting my location as Aus because the 50 ohm will not let my buy less than 40. Just tried it again.

Ah, did not click that you are down under. I forget which local-ish vendors you have - jaycar? Dick smith? Farnell maybe?

I know it can be rough out there when you need some specific piece. I think as long as you meet the 50 ohm 3 watt 1% specs another resistor will work but I realize there is not going to be a ton of alternatives.

I might be amenable to sending a few your way if you can't find a more agreeable vendor.

Edit: OH i see the problem. I buy electronic parts from mouser all the time so i was not bothering to follow the link directly to the part. The OP needs to update the first post - Mouser no longer stocks that 50 ohm resistor loose, only on tape & reel. Try this one, the only difference is that it will have bits of paper stuck to the wire ends:

RS02B50R00FS70

These changes happen all the time in electronic parts sourcing.
 
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Joined
Nov 16, 2003
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Dixie co. Florida
Wombat, I got you PM but your inbox is full, I am very glad the resistors made it all the way to the other side of our sphere, i was worried they might get damaged. Good luck :cheers:
 
Joined
Oct 11, 2012
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9
Yeah I'm only allowed 5 messages total and I keep forgetting to delete the sent box.

I did the mod last night... went well excpet I put a thumb print on the gauge face! D'oh. It was an axious few minutes working out how to clean it off. In the end I used some contact cleaner and got it off 90%. It can't been seen now (the light needs to at the right angle which cannot be done with it installed) the gauge is back in so all is well that ends well.

Only a 3km (1.86mi) drive into work but the needle did lift off the bottom, just, so I think it's working. I've got to do some running around later so that will be the real test.

Thanks again mate for all your help with getting me the resistors and also keeping this thread alive1
 
Joined
Mar 23, 2014
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5
Location
Brisbane, Queensland, Australia
Hi Guys,

Where is a copy of the original Modification you speak of?
I am interested in doing this mod to a 2005 HDJ78R Troop Carrier, I realise it will be different but am sure once I get the general idea can work out the reminder.
 
Joined
Aug 26, 2009
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flat earth Midwest
Peter,
It's back on page one of this very long thread. There's bit and pieces elsewhere in this thread where people discuss different ways to skin the cat, but what you need is right back at the start I think. This mod is well-worth doing for the 80. Obviously YMMV in adapting to a 70 series, but the principles are likely the same, may be an issue of slightly different resistor values, etc.
 
Joined
Nov 21, 2013
Messages
45
Location
San Diego, CA
Just completed this mod over the weekend. Not too difficult at all and I am really pleased with the results. Nice to have a working temp gauge. Thanks for the FAQ!

I have an extra set of resistors if anyone needs them. PM me your address and I will send them to you.
 
Joined
Jul 22, 2012
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2,009
Location
Ann Arbor, MI
Is it possible to swap the gauge from a 93-97 into the 91-92 meter cluster?
The 91-92 sender is entirely different electrically, but it may be swappable with the 93-97 senders. I will check the sender unit info tomorrow.
I hate not having OBDII to be able to read the signals. I wonder if anyone has done something with an Arduino board?
 

murf

Lifer
Joined
Jun 24, 2007
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10,525
Location
Scottsdale, Arizona
was going to do this mod until I hooked up the Ultraguage a couple of years ago. Constantly updated digital info - I cant be blissfully ignorant anymore! :hillbilly:
 
Joined
Mar 23, 2014
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5
Location
Brisbane, Queensland, Australia
"I have an extra set of resistors if anyone needs them. PM me your address and I will send them to you."

These have now been spoken for.

Very kind offer but would you send them to Australia?

It seems there are some changes to the Temperature senders between models or at least between Diesel and Petrol, I say this because last week I was working on a Petrol Troopy that appears to have a Diesel instrument as the taco redlines at 4K!
Either way the temp gauge only just move off the cold mark even when it was quite hot... I checked the gauge and it would go all the way up if I shorted it to the negative (Ground) - a new sensor was installed with no change to the reading.

So my question is do we have a temperature verses resistance chart for the different sensors - idea being that I could calibrate my gauge without having to run the motor.
 
Joined
Apr 9, 2013
Messages
1,280
As an alternative, consider getting a wireless OBD II scanner and keeping it plugged in constantly with a short OBD II extension cord, and using your Bluetooth enabled smart phone and a free app like Torque OBD II reader. In my case, I bought the OBD II scanner ($12 on eBay) and the extension cord ($5 on eBay), and use the free app. Now, when my phone is sitting in the cradle attached to the vent on my dash ($10 cradle so I can look at maps while I drive) I can pull up the Torque app and I have an actual number (F or C, you pick) displayed showing me the actual water temperature. Total cost was less than twenty dollars, I have not modified my truck in any way, and I have an actual number.
This seems to me this is a superior solution because it's cheaper, easier, and gives you more accurate information than the gauge mod.
I'd be curious to know what others think and have done lately in light of the ready availability of this approach rather than doing the mod.
Thanks Mudders,
Russell
 
Joined
Oct 11, 2011
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2,409
Location
Sarasota, FL
I did a torque write up a while back on mud and posted video but like the idea of seeing the gauge movement being more accurate rather than seeing it jump to the red right before your head gasket blows!

I have extra parts if you decide to do the mod ;)

Phil if you still have them I'd be happy to send postage!
 
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Joined
Jun 1, 2006
Messages
554
Location
North Jersey
Last week I replaced the sender sensor (83420-16040) in the head for the temperature gage and now my gage seems a little numb. About seven years ago I modified my gage with Darwood's 150 ohm RD1 and 100 ohm R1 replacement and at flat highway speeds the needle sat at one needle width above center going to two or three above while climbing a good sized hill at 45 MPH Now on flat highway at 65 MPH it sits one width below center and goes to center when I start to push it faster, I haven't tried it on any hill climbs yet but it is not moving as much as before in relation to speeds and strains on the engine. The newer sender is not as beefy as the old one, I only have a picture of the old one (not going to take out the new one for comparison) Does anyone know if there are electrical differences in the two sender units? I like the fact that this sender doesn't send the needle so high as before because it would make me nervous, I never checked with another source, but I don't believe the engine was getting as hot as it displayed. My cooling system is tip-top, 20k ago a new OEM brass core radiator , head gasket, new blue fan clutch refilled with 10,000 CST oil, and flushed every two years with Prestone 50/50 I know its not Toyota red but it's only in there for two years. I only replaced it because it seemed like I was running way too hot, and wanted to see if the sender would make a difference in the reading. Has anyone had similar results? I haven't tested it electrically yet but I assume they wear out.


IMG_8410.JPG
 
Joined
Jun 1, 2006
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554
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North Jersey
I just discovered that there are two senders that are available Nippondenso 83420-16040 and Yazaki 83420-20030 does anyone know the difference and is the Nippondenso the right one for a 1993 motor?
 
Joined
Jun 2, 2015
Messages
5
Location
So. Cal
I did this mod a couple of weeks ago with 100/180 ohm resistors. The gauge reads 150 at the bottom line, 201 when the needle is level and 217 when it first touches the bottom of the red. This is perfect as far as I am concerned. I spent the last three days wheeling around Anza-Borrego and very predictable cooling performance and indications on the gauge. It's great knowing what is really going on and when to back off while cruising through miles of sand.

On a related note, although I was really careful not to disturb the needles, I must have done something to the oil pressure gauge because it now reads a quarter division higher than it used to. I'm not sure if it became magnetized or the armature was moved or what? Has anyone ever seen this?
 

SmokingRocks

I bought a Cruiser to keep miles off my Cruiser
Joined
Oct 6, 2014
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Colorado
Just did this with my 93 after a full coolant drain and fill and thermostat replacement (water pump was replaced 10k miles ago). Everything works the way it should but I do notice that either I am running hot or the gauge is misaligned.

IMG_20160127_074243539_zps2ovkpku7.jpg

At idle with my auxiliary fans on and about 20 degree ambient air the gauge rises to about here. Interestingly when I am accelerating hard the gauge goes down closer to the middle, then when cruising on the flat in 4th gear at about 70mph it goes back up. Perhaps my new thermostat is set too hot?

I was thinking I could plug an OBD2 scanner in and check the actual value but then remembered I don't have OBD2 haha. (Oh and as a side note the tach died about 10k miles ago, the truck is idling in this photo)
 

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