[tshandonay]

Just recently completed a motor swap and am sorting out a few issues. Oddly after driving the car over 100 testing miles the electric fan starting running immediately on startup.

AC is not pressurized yet but fan runs with climate control 100% off.

Anyone have knowledge of what would trigger this?

[tshandonay]

Some more info....car is showing coolant temp as 99 deg C on cold motor. Anybody know where the coolant temp sensor is? Maybe not plugged in?

[tshandonay]

The plot thickens. Start the car (cold) and temp rises from 99 to 101 c after a few minutes. Sensor is working but reading way high. DDE reset of temp or adaptation? I'm a rookie

[BB_cuda]

Air in coolant system?

[tshandonay]

Originally Posted by BB_cuda

Air in coolant system?

Thought of that too. I have a spare temp sensor but am going to try to make sure all the air is out before I go through the trouble of swapping it. Are these car difficult to purge the air?

[BB_cuda]

Idle car with reservoir cap off and look at the little stream peeing into the reservoir. When you see no bubbles in the stream, it should be purged.

To be fair, I did this for only a thermostat swap versus a motor swap so obviously you have way higher potential for entrapped air. The dealer mechanic told me to run the heater while letting it idle with the cap off to push coolant through that coolant circuit too. Good luck and maybe it is the sensor. I wonder if there is a resistance spec on the sensor to check.

[tshandonay]

I idled it yesterday with heat on for 20 min and the stream never showed any bubbles. It was parked on a slight decline however....and I've got 100 miles of driving after filling.

I really don't want to pull the intake off. That stupid sensor is difficult to get to. With I could compare resistance with the spare I have.

[BB_cuda]

You’ve covered my bases then.

The ECU commands the fan off and on per that temp sensor. I’ve run the test on mine (using the cluster temp in hidden menus) and fan cones on at 97c and goes off at 95c. If AC on, fan runs continuous. Sure sounds like a sensor problem.

[tshandonay]

I'm going to swap the sensor tomorrow

[tshandonay]

Swapped with my spare temp sensor. Still reads 99 C.

This car....

[tshandonay]

Checked wiring diagrams and measured resistance right at the DDE. Shows similar resistance to the spare. Both of dropped resistance at a similar rate when warming in my hand. I'm at a loss....it's as if a calibration is off or that this is not where that temp is being read.

I'll have to try it again but I think I started it a couple days ago with the sensor unplugged and the display still showed 99

[tshandonay]

Unplugged the sensor...confirmed no resistance at DDE wiring. Started and still showed a very high temp reading and went up a degree after running briefly as if it was reading from somewhere

[BB_cuda]

Not sure if you dual posted this same problem to FB group NABDOG or not. If not, that guy cleaned the connector related to temp sensor where it connects into DDE. He now gets a low temp value of 27C when car hadn't been run. Fan doesn't have continuous running problem any longer
If it is you, this thread needs the conclusion written in.

[tshandonay]

Thanks for the reminder...I've been meaning to do just that. That was my fb post.

After quite a few hours of troubleshooting I was coming to terms with the fact that I may need a new DDE module. As a last ditch effort I sprayed the pins for the plug that has the coolant temp sensor on the DDE. After letting it dry and blowing out with compressed air the temp reading dropped to right where it belonged. Oxidation or potentially some metallic dust from grinding or cutting in the garage while it say on a shelf was shorting the pins resulting a very low resistance reading. It's been perfect for 3 days now....no codes. I'm hoping to check EGT tonight with ISTA as that was reading at 300C+ on cold motor.