94 silverado inaccurate temp sensor
Asked by Dalton Aug 29, 2022 at 08:05 PM about the 1994 Chevrolet C/K 1500 Silverado Extended Cab 4WD
Question type: Maintenance & Repair
i have a 1994 chevy k1500 with a 5.7 350 i replaced my old coolant sensor
the one on the side of the engine block with a 1972 Silverado temp sensor
because it was the only one i could find at my auto zone with a one wire plug
and the truck when i crank it will slowly rise all the way to 260 degrees when
i check it with a temp gun the truck is only at 180 or 190 i checked the wire
as far as i could without completely destroying the plastic covering over the
wire harness and couldn't find a nick in the wire if anyone has any ideas itll
be greatly apricated
7 Answers
Wrong sender, you need one for a 1994 as the way the gauges work between the two year models is completely different. Why didn’t they just order you one overnight? However if you still feel that there is a wiring issue you can always install a manual set of gauges.
What I'm seeing on Rockauto.com is you need AC Delco part number 21377 AND pigtail part number PT728 to replace the original one blade sensor with the newer style two blade sensor. Basically the PT728 is an adapter plug that allows you to use the new sensor. Rockauto.com also has kits for this that come with the sensor and adapter plug together. Just put in your vehicle information on the website and under cooling system you'll see them. Personally I'd go with the AC Delco sensor and pigtail. GMs don't like aftermarket coolant temperature sensors to begin with. So, what has happened in your case is you were sold a temperature gauge sending unit. Not a coolant temperature sensor. In 1972 there was no such thing as a coolant temperature sensor. The child working at Autozone didn't know that! He also didn't know that coolant temperature sensors and temperature gauge sending units work by using variable resistance to ground. As the sensor gets hotter the resistance gets lower. This provides more grounding to the temperature gauge and the needle on the gauge moves up to show you the temperature of the engine coolant. The reason why your gauge is not accurate with the new sending unit is because the resistance value of the sending unit is wrong in relation to the gauge on the dash. It's lower than it needs to be for the gauge to work correctly! Hope that helps! Jim
Thankyou for your help I ordered the parts and can't wait to see if it fixes the problem thankyou
You're welcome. Glad to help! Please keep us posted. Jim
Thankyou for your help the parts finally came in and work great
You're welcome. Glad to help! That's awesome! Thanks for letting us know!! Jim
