Impala-Ryder

Hello, I need to test My Cars Dash Coolant Temp Gauge because I'm having a P0117 Code and I have changed the sensor and still didn't solve it, My Cooling fans are coming on on cold engine. I have tested the sensor and it checks out, I have 5V at the Connector. From what I understand a faulty Dash Temp gauge can mimic symptoms of bad ECT sensors and create all sorts of trouble.
So can someone provide Me with info on how to test the Dash Coolant Temp Gauge??
Thanks.

tech2

the code is for a short/low voltage
answer these questions...I need all answered to continue.
Is the code active or stored?
with the car cold, sitting overnight...compare all the temp sensor readings...they should be close to each other...ambient temp, ect, trans fluid.
if its active all the time, unplug the connector and see if the high code sets p0118

Impala-Ryder

Its Active All the Time, Hence the Fans blowing on cold engine..
I cleared the codes, before taking My thermostat housing off to get to the Coolant Sensor to Remove it, due to no room/space at all.
But, I haven't ran the engine in for a few days and when I was running the engine the code was there all the time.
Using My scan tool, I can see that the PCM is getting Temperature Readings, Probably Just not being communicated with the Dash Temp Gauge..??
Scan tool shows temp reading for the Intake Air Temp and the Coolant Temp 53*F (Or 12*C) and 50*F (10*C) respectively, which is just about the same for a cold engine. And when I Unplugged the Coolant Temp Sensor Connector, It also registered as -38*F.

Hope this answers Your question or gives You enough info You need.

tech2

if you are getting the low code when plugged in and get the high code with the sensor disconnected....have 5volt reference at the sensor connector, a good grd wire at the sensor connector....you may have a bad new sensor.

try a oem senor from the dealer.

if you really wanted to; you could disconnect the pcm connector and check for short for short to grd on the signal wire.

Impala-Ryder

I think I've found what it is, I Just need to know where to go next from there.... So this is what happens, at the Cooling Fan Relay #1 Socket, The Computer Or Something is sending a ground (Or Power) to the bottom right pin socket (Pin 85, I believe) This shouldn't be happening, I believe the way it's supposed to work is when The Engine gets Hot the bottom right socket (Pin 85 I think) Receives command from the PCM to Run the Fans.... But, Mine triggers at cold engine (It runs Continuously when the Engine is Running) and again at Ignition Off, which The ground (Or Power) is Present at Pin 85 (Correct Me if I'm wrong) also Fan runs for About 2mins after Ignition is turned off then Fan turns off (i.e the ground goes out at the bottom right socket)
I have the cooling fan Relay Diagram but have a hard time reading/interpreting it. Maybe You can read it/help. I Just don't know where the Ground is coming from..I have a feeling is a compromised wire somewhere, But I don't know what to do next.

I made a short video of what's happening.

tech2

when the pcm sees a fault with the coolant temp sensor... the pcm has no information on coolant temperature. to prevent an overheat condition.it turns on the coolant fans. this is normal. When you fix the temp sensor...the fan will stop turning on.

Impala-Ryder

I would definitely Love to do this, Is checking for short to ground on the signal wire a visual check or Check that is done with a DMM?

Impala-Ryder

After all day and all night of Frustration and confusion, I surely did disconnect the PCM and Visually inspected for any damaged wire(s), but everything seems right and tight in place. I wanted to do a quick continuity test on the Coolant temp Sensor wire, but, did not know which one the Pin is, I know its a Yellow wire, But, there were like 2 or 3 or More solid Yellow wires at the PCM. So I didn't know which one to test.... ?? 😏🤔