coolant temp sensor

[terrydmorgan]

I'm installing an LS1 from a 2003 Vette into my 1969 Camaro, and I'm looking for a place to locate a coolant temp sensor for my electric water temp gauge. I have two temp sensor installed: 1) factory sensor is in the head on driver's side near the front of the engine (connected to ECM); and 2) in the head on the passenger side near the rear of the engine (electric fan input). My factory ECM has an output labeled coolant temp, but it won't drive my electric gauge, so I assume I'll need another temp sensor. Any suggestions on where to locate it?

[anthonys 69]

Doesn’t your ecm have the capability to run the cooling fan most do including stock ecm

[terrydmorgan]

Anthony,
I just assumed the line labeled water temp carried a signal indicative of water temp (like for a gauge). But, perhaps it is a fan control. I'll put a multimeter on it tomorrow and see what it does. Thanks!

[garys 68]

I'm pretty sure the 99+ gauges are all stepper motors, so the ecu output wont work with a standard gauge.
You've got a few options.
You can use the ecu to control the fan(s) and use the rear passenger head boss for your gauge sender.
You can swap out the coolant temp sender and pigtail for 98 f body. It has outputs for the ecu and an additional output wire for analog gauge. You may need to add a resistor to get it in the correct range for the gauge.
The drivers side block plug can be drilled and tapped for 1/2" NPT (I did this for my 68 corvette temp sender).
Drill and tap the top water pump boss that's used for the truck water inlet.