1969 -1972 Water Temp Sensor resistance (2 Viewers)

[120mm]

I'm currently attempting to troubleshoot my inoperative water temp system in my 1969 FJ40 with a 1984 2F.

It has never functioned, but I have the proper parts to effect the conversion.

While troubleshooting, I ohm tested the sensor, which returns 38 to 39 ohms regardless of temperature.

I'm assuming the new sensor is bad but want to survey mud to see if I'm missing something.

 

[locklaw]

This should help -

Resistance should change with temperature, your gauge must measure correctly and most importantly, too much thread sealant will make your sender be unable to ground. Measure continuity between the sender outer and a known good ground.

 

[Scota4570]

I am dealing with the same thing. I got a new sensor. IT came from an on line vendor. IT has the correct part number an appearance. IT was previoulsy opened by someone else. It was part of a gauge and sender that was broken up. Mine also does not change resistance with temperature. It also measures about 45 ohms.

I have a known good gauge comeing in the mail. I am going to the dealer to buy a sender today. I will bench test it all before installing. I drew a schematic showing what mine is doing.

I will be watching this thread and will report what I figure out.

 

[Engineer8000]

,

 

[Scota4570]

Any link to "the big cluster thread"? I'd like to understand how it works so I can get a working gauge in my vehicle.

I should be able to wire it all up with test leads on the bench. Then I should be able to put he sender in hot water and see the needle on the gauge move. Am I missing some important detail?

 

[120mm]

This should help -

View attachment 3355354

Resistance should change with temperature, your gauge must measure correctly and most importantly, too much thread sealant will make your sender be unable to ground. Measure continuity between the sender outer and a known good ground.

Pretty sure my cluster is a second generation. Don't understand the relevance of the picture.

I am not using sealant.

What do you mean by "sender outer"? The outside of the sender is literally in direct contact with the block, so it is already grounded.

 

[120mm]

Any link to "the big cluster thread"? I'd like to understand how it works so I can get a working gauge in my vehicle.

I should be able to wire it all up with test leads on the bench. Then I should be able to put he sender in hot water and see the needle on the gauge move. Am I missing some important detail?

I've already looked through the big cluster thread. It's a crapload of random information chaotically organized and I get more confused reading it every time I do.

The picture you posted is my understanding of how it is supposed to work as well.

It's very popular on 'Mud to "help" people out and appear knowledgeable to post a link to this voluminous and confusing thread or even better, to just refer to it obliquely.

Here it is so I can feel like I've "helped."

Clusters, Gauges, Speedo & Odo meters

There seems to be a lot of questions about Clusters, Gauges, Speedo and Odo meters, so I thought why not set up a page as a reference guide / database / knowledge center? Over time I collected a lot of pictures. I created a Gallery with all the photos I have, which you can see here...

forum.ih8mud.com

Good luck wading through all that.

 

[120mm]

Oooh. And there is also the super helpful "test the water temperature gauge according to the FSM" helpful tip.

When you post that, it makes you seem SUPER informed, though if you check the FSM, there is no procedure for testing the water temperature gauge. There is a description on how it's wired, and instructions on how to remove and reinstall, but no procedure for testing.

 

[120mm]

Here's the complete pic showing the parts numbers and other info. Note there is no ohm reading specified for 2nd generation.

 

[120mm]

I found an open in the wire between the four way connector leading from the instrument cluster and the sensor, and now, at last, I have a functioning water temp gauge. I used the picture @Scota4570 posted to develop a plan for diagnosis and determined the gauge and sensor were good so I started ohm testing the wires

 

[Scota4570]

This is good stuff. My gauge is not exactly like the picture above. Mine has marking on it. I have a new gauge in the mail. I have a new sender due in tomorrow. I will see if they match based on the chart for gen 2.

 

[120mm]

Aaand it runs exactly where my 1975 FJ55 does. Right on the lower middle range mark.

 

[120mm]

This is good stuff. My gauge is not exactly like the picture above. Mine has marking on it. I have a new gauge in the mail. I have a new sender due in tomorrow. I will see if they match based on the chart for gen 2.

View attachment 3355791

The Yazaki Meter marking is merely covered up by the instrument cluster cutout.

 

[locklaw]

I found an open in the wire between the four way connector leading from the instrument cluster and the sensor, and now, at last, I have a functioning water temp gauge. I used the picture @Scota4570 posted to develop a plan for diagnosis and determined the gauge and sensor were good so I started ohm testing the wires

View attachment 3355789

Wow, aren't you a ray of sunshine.

So the FSM page which you so berate was the actual answer (no power to the sender, the first logical test) whereafter one tests ground.

Furthermore, it seems that actually applying the right amount of heat to the sender (which can be garnered from the generational cluster gauges and senders image and thread which you find so hard to comprehend showed your sender works as it should.

Same story on your brake issues listed in your build thread. All vendors have their heads up because they don't have 360° images of the exact part yet the vendor suggested provided you the bolt-on solution needed.

You might wonder why people refuse to help you, particularly given the attitude you exude towards genuine attempts to help. Not all forms of help in life will be spoon fed solutions or Crayola drawn pictures but rather, knowledge and concepts which will serve to guide you to the answer.

 

[Engineer8000]

.

 

[Engineer8000]

I've already looked through the big cluster thread. It's a crapload of random information chaotically organized and I get more confused reading it every time I do.

The picture you posted is my understanding of how it is supposed to work as well.

It's very popular on 'Mud to "help" people out and appear knowledgeable to post a link to this voluminous and confusing thread or even better, to just refer to it obliquely.

Here it is so I can feel like I've "helped."

Clusters, Gauges, Speedo & Odo meters

There seems to be a lot of questions about Clusters, Gauges, Speedo and Odo meters, so I thought why not set up a page as a reference guide / database / knowledge center? Over time I collected a lot of pictures. I created a Gallery with all the photos I have, which you can see here...

forum.ih8mud.com

Good luck wading through all that.

Remind me to never attempt to help you.