Hooked up a scanner to my car yesterday to verify my temp. gauge reading. While the gauge reads 260 deg. when the fan comes on, the scanner is telling me that the temp. is only at 225 deg. Fan goes off at 217 deg. (NORMAL). What would be throwing off the gauge like that, but still have a properly working system.




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Rob Kowalski
85 IROC, 305 TPI, JET AFPR - 45 PSI, B&M Megashifter, B&M Shift Kit, 3.42 gears, SLP Airfoil, SLP 1 5/8 headers and cat back system, gutted cat, gutted airbox, MAF screens removed, K&N, more to come!!

 

I would check continuity between the gauge and the sender. Alot of problems are with connections and wires themselves, not nessasarily the gauge or sender. Its possible that your sender is screwed up tho. It is the one located in the driver side cyl head with a green wire going to it I think. Check to make sure the wire isnt burnt, it sits really close to the header.

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Mike C
88 Iroc 5spd
355 TPI, AFR 190s and lotsa other mods
April feature ride at Sethirdgen.org

 

Mine is off in the opposite direction. When my car is running 180 it says 135. I know this becuase I to used a scanner. I think it is my dash that is miscalibrated. That might also be the case with you.

 

There is another explanation....the ECM coolant temp sensor may be bad too....dont trust what a scanner says, just because it is a scanner. Sometimes the gauge is right, and the ECM temp sensor is wrong.... Something to think about.



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Mike Metzler (Desert86Roc)[*] Check Out:SpeedWorldMotorplex.com[*] Check Out:Chevrolet F-Body Online Part & Illustration Manual[*] My 86 IROC 305 TPI Page (406 build in progress)

ET's @ 1250 ft[*] 14.28 @ 95.461 mph (uncorrected, NOS, no headers)[*] 15.362 @ 88.238 mph (uncorrected, headers, no NOS)
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My guess (and I emphasize "guess") is that your guage sensor is bad. If you were actually running 260° you would know it in other ways.

Since your fans are coming on at app. the right temp for the CTS/ECM combo I would look at the guage sensor, or maybe replace them both (they're cheap enough for peace of mind).