Trans cooler guage

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Jul 27, 2006 | 12:26 PM

sofdchief

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Joined: Oct 2004

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From: South Onondaga, NY

Trans cooler guage

Hey folks....got a question for y'all.....

I started my '02 F250 SD 4x4 last night, and the "Check Guage" light went on. This is a new one on me.....never had ANY truck do that. Needless to say I 'checked' the guages and found them all working, EXCEPT my trans cooler guage. It was bottomed out completely. Guages are stock...nothing aftermarket. There have been no aftermarket mods done on motor or tranny. I did have trans cooler lines replaced a month or two ago, as well as a trans fluid flush.

Any thoughts??

Thanks guys.

Jul 27, 2006 | 02:44 PM

rustyoilpan

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Joined: Jul 2006

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Have you checked to see if the harness is connected to the sensor? Even if it is, unplug and check for corrosion or dirt then reconnect and see if it works. also check for damage on the harness.
Hope this helps.

Jul 27, 2006 | 02:49 PM

sofdchief

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Joined: Oct 2004

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From: South Onondaga, NY

harness

Thanks for the input. Can you describe where this sensor is connected? Since all this started last night, I haven't had a chacne to look into anything yet, but i will when I get home tonight.

Thanks for the help.

Jul 28, 2006 | 06:55 AM

Casey

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It's on the valve body, inside the transmission. That isn't the problem.
It's either a bad sensor or a bad wire between the sensor and the PCM. There is a lengthy diagnosis chart in the shop manual to diagnose this.

Jul 28, 2006 | 07:18 AM

sofdchief

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Joined: Oct 2004

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From: South Onondaga, NY

sensor

Casey- Thanks for the info. Now, any chance you could explain how I go about diagnosing/fixing the issue? Also, will it cause any problems if not taken care of immediately? I do not do a lot of excessive towing, in fact I hardly tow at all lately, so the transmission is really not being worked all that hard.

Thanks

Jul 28, 2006 | 08:58 AM

John7894

Cargo Master

Joined: Jan 2002

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From: LA and CO

The trans temp sensor is on the valve body? Also, is it an actual temp "sensor" or is it a temp "switch".

I'm asking because my dad has an 02 and has never seen the needle move. It moves to the same position in the middle every time the truck is running.

Jul 28, 2006 | 09:29 AM

Casey

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It's a sensor, and it's on the valve body. It sends actual temp data to the PCM. The PCM sends this data to the instrument computer. That computer decides where to place the needle, based on the temp data. It's the instrument computer that makes the gauge look like a switch.

Quote:

Now, any chance you could explain how I go about diagnosing/fixing the issue?

You could find a wiring diagram for the truck and remove the passenger's side main wiring loom from the trans. Check the continuity of the two pins going to the temp sensor. There is a chart (I don't have one) that shows what resistance to expect at different temperatures. If that is bad you need a new temp sensor.

You also need to check the wiring continuity from the harness connector to the PCM.