I was out there trying to figure out why my temp guage no longer works , it shows the same amount no matter how long it runs , and it is barely reading on the scale at all.I know there is a temp sensor on the top of the manifold , which is brand new , I replaced that when I put the engine in so that should be good.Everything was running fine , but now no temp guage.Anyway , I found my electrical manual , and according to it , the 2.8 has 2 temp sensors , one on the top , and then one on the side with a totaly different plug , its a yellow wire with a black stripe on it , and its right by the plastic peice that clips to your valve cover bolt to hold a wire harness away from the manifold.Now , I have no idea how old that is , or anything.This just seemed to start after I hooked up my battery isolator , well maybe before as I haven't really driven it a whole lot since I put the tranny back in.

Any thoughts or ideas on this?How can I check if the sensor on the head is working?Its just 2 little prongs sticking out , and the plug that goes to it is black.I'd take a pic , but my camera is charging after taking some pics of what I did with the fender flares.

Top manifold one is for the ECM and the side one in the driver's head is for the dash guages. If the engine runs well and warms up correctly than I would deduce the ECM temp sender is working fine. If you decide to change it they are very cheap also. Used in a million GM applications.

The truck runs fine , but without the guage , it kind of makes you lerry not seeing the temp.The one in the head is probably what went on me.I'll pick one up tomorow and swap it out.The one on the manifold for the ECM is new.I was just confused why there would be 2 senders on the engine like that.

Hey, Barak, & Chris,

Where is this second temp sensor located? <img src="/forums/images/graemlins/confused.gif" alt="" /> Not the one located near the upper radiator hose connection atop the manifold. So that we're on the same page, is the sensor outlined in red below, the sensor that is utilized by the ECM?



If that is correct, again, where is the temp sensor located (pic or manual page?) for this? TIA! <img src="/forums/images/graemlins/cheers.gif" alt="" />

Look on the front of the driver side head.

Richard <img src="/forums/images/graemlins/patriot.gif" alt="" />

There is s small wire harness that goes down from the top of the engine past your manifold that has the wires that go to your oil sending unit and stuff.Off that wire harness there is a little plastic clip that clips onto your valve cover bolt to hold the wires off of your manifold.There will be a yellow wire with a black strip plugged into a sensor there on the front end of the head with 2 little prongs when you pull the wire off.Thats the one that I believe is gone , and it seems thats the one for the guages.

Well , checked the auto parts places around here , no one has a listing for anything other than the one that goes in the intake for the ECM.There is no listing for the guage one.Hopefully someone on here has replaced the part before and has a part number , or even better , Jerry if you see this , is there another name for the guage temp sensor that goes in the head by the manifold?A part number would be even better <img src="/forums/images/graemlins/smile.gif" alt="" /> <img src="/forums/images/graemlins/kewl.gif" alt="" />

Try this:

AIRTEX Part # 5S1537
**Non-stock item--shipping delayed up to 2 business days**
$30.79

http://www.rockauto.com/catalog/x,carcode,1177051,parttype,2188

http://info.rockauto.com/Airtex/Detail.html?5S1537.jpg

BTW the temp gage on my old 2.8 Troop never read much above 1/4 anyway, except for when it overheated after blowing a heater core hose and it read almost 1/2!!

My 3.4 will read just a bit higher than 1/4 but not much. I don't think Isuzu calibrated their temp gage very accurately to the GM-style sending unit in the cyl head.

You can check the entire gage ckt by grounding the wire that connects to the temp sender, then turning the ign on (or maybe it needs to be running, I forget!); you should get full-scale deflection on the temp gage.

HTH...........ed

P.S. looks like you'll have to copy and paste that first link into your address bar, it didn't linky-fy very well.

#50093 on partsamerica.com, only bad part is it's $35. I would just get one or two or three from a junkyard. How do you know the sensor is bad, maybe it is the connection.

I'll test the connection tomorow and see what happens.If its not the connection then I'll replace the sensor.