Temperature sender/sensor... 7.3L

[groundhogy]

Hi All,

I think RV'ers tend to have a diverse knowledge of things.
Now that you're buttered. lol

My temperature sender/sensor is doing odd things.
It was just replaced (and I don't wish to contact them again.).

It is either all the way hot, or all the way cold. Occasionally I've seen it in the middle.

This morning I watched it carefully, as it was in the rare middle position. Within a few minutes I saw it rise to all the way hot. Pegged.

Then during the day it will switch to all the way cold.

Anyone ever heard of this happening?

[Gjac]

groundhogy wrote:
So the one has 5vdc.

THe other is ground and measures about 10 ohms from it to something on the block.

When I ground and open the +5v line the gauge reads zero hot to pegged hot (grounded).

If you set your meter to ohms and touch the positive and negative lead together what do you read? This is what you should read when you touch the terminal end to the engine block to check ground. Your meter may be off some that is why I say it should be the same.

[groundhogy]

THink this proves the gauge and wiring is good.

[groundhogy]

So the one has 5vdc.

THe other is ground and measures about 10 ohms from it to something on the block.

When I ground and open the +5v line the gauge reads zero hot to pegged hot (grounded).

[Gjac]

groundhogy wrote:
I didn’t try measuring that since it is a 2 wire situation.
Ground matters in this situation?

Yes one wire is positive and has volts which you measured, the other should be the ground wire. Set your meter to ohms and measure from the terminal to the engine block and see what you get, if anything.

[groundhogy]

Measured 5vdc at the two wires

[groundhogy]

I didn’t try measuring that since it is a 2 wire situation.
Ground matters in this situation?

[Gjac]

What did your ground wire read between the wire terminal and the engine block?

[groundhogy]

SW5130 is the motorcraft part number listed for both 7.3 and 6.0

[groundhogy]

So in 2003, it was the last year gor the 7.3L. They changed over to the 6.0L that year.

I just went on Rock auto and looked at the 6.0 trmp sender... looks mechanically the same to my eyes..

[groundhogy]

This is what I measured from the sensor and the connector terminals

-4.4 kohm at 60F
-5vdc on connector
-gauge 1/3 at 60F

[groundhogy]

I will put a multi meter on both sensor and wires tomorrow probably.
Also someone mentioned looking up the proper sensor ohms range.

It is a 2 wire affair.

[Lantley]

I had 2 issues with my 2019 truck involving the connector ...not the sensor or the wire.
The sensor is covered under warranty , wire and connector are not! Go figure!

[Gjac]

Do you have one wire or two wires going to the sensor? If one, the ground is through the treads to the block and could be bad. I would remove and check threads clean and reinsert. If two, one is a ground wire, check it to a known ground. The other wire should have voltage to it, voltage will vary as sensor get hotter. Turn key on to see if voltage is there. If you have voltage on one and ground on the other your sensor or gage is bad if you are missing ground or voltage one of your wires is bad.

[groundhogy]

BurbMan... you are already fully buttered. And my mom always told me it's a sin to waste butter.
But you beat me to it. That's the first thing I thought of when I saw the Radio Shack reference.

I watched it more carefully this morning.
At first key turn, with engine cold... the gauge was at 1/4 hot.
Then in about 5-7 minutes, it drifts up to full hot.

Then the red light comes on telling you to look at your gauges, something is wrong.

Then at some point un-noticed, the needle is back to full cold.

If this happens every day the same way, then how can this be a chaffed wiring issue?

Also, the temperature circuit worked fine when the old sender was good (granted it's been broke for about 6 months though).