I checked where i extended the wires they are good connections, but i still get a code 15, and when i look at the coolant temp with WinALDL It reads -38.7 degrees constantly. What could be the problem?

Thanks, Chris

 

Bad CTS or bad wiring. Cold = high resistance

Step 1, check resistance of CTS. At operating temp it should be around 3-500 ohms

Step 2. Check wire resistance. Put a paperclip / shunt between the terminals in the CTS connector and check the resiatnce between at the ECM connector.

Step 3. replace ecm

 

I'd replace the coolant temp sensor. Unless you did this already........

 

Well, Ed already gave a thorough description, so I don't have much to add except that every single CTS failure results in the -40 rating. It could be wiring, but the chances are good the sensor just tanked.

 

Yeah Jim, but IIRC a dead open will also give -38.7 as well. Thats just the lowest reading the ECM will read when R is way high. So it still could be wiring or A/D in the ecm.

 

You're absolutely right ed. I'm not disagreeing with you. An open circuit will push the resistance high enough (in the case of an open circuit, to infinity) for the computer to register the minimum temp.

The only point that I was making was that wire failure is far less common than sensor failure. Unless there's an obvious cut or melted spot in the wire, it's a pretty safe bet that it's the CTS. If we were talking about something expensive/difficult like a fuel pump, then I'd definately take the time to make sure it's not the wiring, but with a $15 part, it's usually worth the gamble to just change it.

 

I got a new one when i switched to the LT1 intake. Would the threads being wrapped with teflon tape effect anything?

Thanks for Your help I just need to go find a Voltmeter now.

 

Hell, the cheapest way to check would be to slap a 300 ohm resistor in there with the engine warmed up. 300 ohms is ~ 185' to the ECM, no 15.

Had to do this myself last month because of a fubared connector... a 0.10 pack of resistors can let you schedul maintenance at your convenience.

BTW, i mention the wiring because he mentions extending it. Sure he says he checked it, but i can't assume he actually ohmed it, knowhatimean