BD Turbo Cool Down Timer 2

What Is The Cool Down Timer 2 (CDT2)?
The CDT2 is designed to keep the engine running when the ignition key is turned off and the exhaust temperature is above a set point (between 250-550°F) to prevent turbocharger bearing failure that could occur when the engine is shut down too quickly.

A typical turbocharger can spin in excess of 100,000rpm under load, which will continue spinning when the engine is turned off.

The turbocharger is lubricated and cooled by the engine oil, and when the engine is turned off, that oil supply is cut off. If a turbocharger is still spinning at a high RPM when the oil supply is cut off, the internal bearings will utilize what remaining oil is around them then start to heat up - essentially cooking the oil, which causes premature bearing failure. By allowing the turbocharger to slow down to a safe RPM, this bearing failure can be prevented.

A very efficient means of gauging a safe time to turn the engine off is by the exhaust temperature. The suggested temperature range to go by is below 400°F (with the thermocouple mounted post-turbo). The further away the probe is away from the turbocharger, the lower the shut-off temperature should be. If the thermocouple is mounted pre-turbo, then the shut-off temperature can be higher.

How Does The Cool Down Timer 2 Work?
The CDT2 module utilizes the signal from the thermocouple that is measuring the exhaust gas temperature. The thermocouple may already be connected to a gauge or it can be connected to the CDT2 module on its own.

When the key is turned off and the exhaust gas temperature is above the shutdown setting, the CDT2 module will keep power supplied to the ECM/PCM, which in turn will keep the engine running until the temperature falls below the setting.

As well a new feature of the CDT2 is to shut the truck down based on an adjustable time. This time is adjustable using the potentiometer on the side of the control unit.

Safety Features
The CDT2 module has a few safety features built-in that the driver should be aware of. If for some reason the exhaust gas temperature does not fall below the shutdown setting within five (5) minutes from the key being turned off, the CDT2 will automatically shutdown the engine.

As well if the engine starts to initiate a REGEN cycle causing the EGT’s to rise the CDT2 will shut the truck off.

The CDT2 module is also designed to monitor the vehicle’s hydraulic brakes when it is connected to the brake pedal switch via the Brake Pedal terminal on the module. While the CDT2 module is keeping the engine alive (ignition key turned off and exhaust gas temperature above the shutdown setting), if the brake pedal is depressed the CDT2 will shutdown the engine. This was implemented to protect the vehicle from being stolen when the engine is in cool down mode; eventually the brake pedal would have to be pressed which will shutdown the engine preventing the thief from easily driving away with the vehicle. This is also useful in situations where the engine needs to be shutdown immediately or is desired to be shutdown sooner.