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My stock temp gauge is not working. I have replaced both coolant temperature sensors. I have unplugged the sensor that sends the reading to the gauge and grounded the plug, and the gauge spikes hot. When I am cranking the truck it spikes hot. But when the truck is actually running it has no reading at all. I have looked all over for information but cannot find anything, so if this has already been answered just point me in the right direction and delete this post. It's driving me crazy trying to figure this out. Thanks in advance!
 

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It is possible that the gauge is bad. They can be swapped out with some gentle hands, but you will need some kind of scan tool to verify the correct temp reading when repositioning the needle. For grins, I would get ahold of a scan tool of some kind to see what your PCM is reading. Since your truck is s 94, you have an OBD I PCM setup. I believe there are several relatively cheap scan tools that can be bought and or fabricated relatively cheaply. Here is a link to another thread that you might get some useful information from.


http://www.dieselplace.com/forum/63-gm-diesel-engines/21-6-5l-diesel-engine/779258-temp-guage-wrong-temp.html
 

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I'm thinking you got a ground issue. Spike during cranking is what makes me think that.

For a quick test take some jumper cables and clamp em between battery neg, body, and engine and see if anything changes. If it does you have to go figure out which grounds are missing or bad.

Being a 94 it should have a PMD so its kinda amazing that it actually runs. Lots of us end up pulling our hair out with running issues and eventually find one dang ground wire is corroded.
 

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My stock temp gauge is not working. I have replaced both coolant temperature sensors. I have unplugged the sensor that sends the reading to the gauge and grounded the plug, and the gauge spikes hot. When I am cranking the truck it spikes hot. But when the truck is actually running it has no reading at all. I have looked all over for information but cannot find anything, so if this has already been answered just point me in the right direction and delete this post. It's driving me crazy trying to figure this out. Thanks in advance!
When you replaced the Sensors did you use AC Delco (sensor for gauge): #213-77.
AC Delco (sensor for PCM): # 213-928..???

If you used any other brand you will get Gremlins.
 

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Discussion Starter #5
I have ac delco ordered. The the two sensors currently in it are not ac delco. But I know for a fact they are working. I'm sure it is just grounded. Here is another question though. The one green wire coming from the sensor that goes to the gauge, does it go straight to the cluster?
 

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Discussion Starter #7
Thanks guys, I just download all the 94 .pdf files in the FAQs haha. I found the wiring schematics I needed and will get to work finding the problem when I get time (christmas and all that). I will let you know how it turns out. Thanks again
 
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