Bad ECM or something else?

[Alain]

I suspect a faulty ECM on my 2015 LR4. I have the following symptoms:

1. Overheating. I suspect the ECM is not energising the electric thermostat. The upper radiator hose is never hot.
2. Viscous fan is always engaged.
3. No communication with the OBD socket. See attached picture. I have confirmed 12 volts on pin#16.
4. The amber warning indicator light in ON. No engine light.

I replaced the following parts:

1. Coolant pump
2. Viscous fan
3. Thermostat
4. Electric auxiliary coolant pump
5. Rear crossover pipe with an ECT1
6. Main radiator

A combustion leak test is negative.

Any comments, recommendations?

 

[scapistron]

Are your coolant temps appearing normal?

 

[Alain]

At idle, coolant temp is normal for about 45 minutes, then overheating rapidely. I can't monitor actual temperatures of ECT1 and ECT2 because no communications via the OBD socket .

 

[scapistron]

I'd look around for signs of mice damage. I know they like to get in behind the battery.

 

[Alain]

I replaced the battery last month. The battery area looks clean.
BTW, the auxilary battery is dead.

 

[powershift]

I know you replaced the t-stat but that is what looks to be the problem. Did you buy it on Amazon?

 

[Alain]

The shop replaced the thermostat with a genuine land rover part.

 

[Alain]

I had the thermostat replaced twice.
What's are the comments from a non land rover part?

 

[scapistron]

Did they put in the right thermostat?

A new ECM seems like a pricey maybe fix. Any signs of corrosion on the ECM connectors?

 

[jlglr4]

To my understanding, the electronic thermostat is still primarily a thermomechanical mechanism that, in addition, has a heated wax element that the ECM can use to open the thermostat a bit faster when desired. But, the thermostat will still fully open in response to rising coolant temp and a malfunction in the ECM should not cause overheating.

You might check to see that the electrical connection to the viscous fan control unit is sound and that there is voltage at the connection. You mention that the fan is on; however, I believe the fan will run even when the electrical control is not working - it will simply run at a set speed and will not increase in response to coolant temperature changes. It probably wouldn't make much difference while driving with good airflow through the radiator, but it might be cause overheating while idling at a standstill for 45 min.

I don't have any clue about the OBD. I'm not familiar with the Autel systems. Have you had it working with this car before? Have you tried a different scanner (even just a cheap one) to see if you can get any reading - rule out a problem with the scanner itself?