Active grill shutters, higher operating temps

Crobinson16 · December 12, 2017

I'd like to know if there is an operations check or system check that I can do to see if the grill shutters are functioning properly. I'm not get a dtc or anything but this truck 2017 silverado 6.2l LTZ Crew cab has higher operating temps as in water temp and trans temp the other 6.2 I've driven. Water temp rises with slightest engine load and rpm. I'm starting to think these grill shutters are staying closed longer than needed.

Doug_Scott · December 12, 2017

The ECM will set a DTC code if there is an issue with the shutters. What are you using to monitor engine temps? Try using a scan tool to monitor the coolant temps while driving.

Shutters are a good way to stabilize temps, and have been used for decades in large commercial vehicles. They should reduce temp variations, not increase them.

Anyone know if GM is using the shutters to replace the thermostat?

Grumpy Bear · December 12, 2017

The purpose of the shutters is to bring the motor to temperature more rapidly. They still have a thermostat. Thermostat housings have a small bypass which use to be part of the thermostat proper. A small bleed to prevent air entrapment and keep a safe minimum flow on the pump. Deadheading a pump is never a good idea. Trucks, meant to carry loads, have generous cooling systems and at times even the small bleed of water will retard engine heating and if cold enough and load low enough even prevent full warm up. A radiator is a basic fin fan exchanger. Limit it air, limit it's capacity. This is a good thing. Warm engines are more fuel efficient and emit lower emissions. Be happy.

As for the temp cycling. Until there is enough load on the motor to keep the thermostat open and throttling there will be some normal vacillation as it cycles open and closed. This will change in amplitude and frequency with the changes in weather. More in cooler weather and less in warm.

Don't worry that you wont have enough cooling capacity when fully loaded. That thermostat will open and the shutters will too.

Edited December 12, 2017 by Grumpy Bear

Crobinson16 · December 12, 2017

55 minutes ago, Doug_Scott said:

The ECM will set a DTC code if there is an issue with the shutters. What are you using to monitor engine temps? Try using a scan tool to monitor the coolant temps while driving.

Shutters are a good way to stabilize temps, and have been used for decades in large commercial vehicles. They should reduce temp variations, not increase them.

Anyone know if GM is using the shutters to replace the thermostat?

I did use a scanner to read temps at the ecm.

newdude · December 12, 2017

What temperatures are you seeing? What year other 6.2s have you driven?

Crobinson16 · December 12, 2017

I have a 2017 and driven other 17s 6.2 as well. There is a post about it, titled New Sierra 6.2, someone else posted about it and I posted to it as well

Logan Lanfear · December 12, 2017

What are you seeing for temperatures?

Crobinson16 · December 12, 2017

Under normal driving conditions, readings ecm are 215-225, and under acceleration to pass someone or go up an incline 225-230. Temps rise with engine rpms not putting load on motor

tbarn · December 13, 2017

The shutters on these trucks are not for engine heat. They are for aerodynamics. They open at times when the truck may overheat.

The active grille air shutter system closes shutters in the front grille to enhance vehicle aerodynamics in driving situations where cooling and A/C loads are relatively low and high levels of front end airflow are not required. If high levels of airflow are required the active grille air shutter system will open one or both shutters. The control signal from the engine control module, ignition and ground circuits enable the active grille air shutter actuators to operate. If the conditions for opening the shutters are reached the engine control module commands the active grille air shutter actuators to open one or both shutters.

Edited December 13, 2017 by tbarn

Crobinson16 · December 13, 2017

It's also controlled by an ambint air temp sensor, and if the shutters stay closed the engine temp is going to rise. I tried everything to see if they would open, now I can't check it when I'm driving. But I turned the AC on full bore , put it in drive , set the p-break and still couldn't see them open. Fact I've never seen them open wether running at idle or parked shut off.

Logan Lanfear · December 13, 2017

Are your fans running?

Doug_Scott · December 13, 2017

3 hours ago, Crobinson16 said:

It's also controlled by an ambint air temp sensor, and if the shutters stay closed the engine temp is going to rise. I tried everything to see if they would open, now I can't check it when I'm driving. But I turned the AC on full bore , put it in drive , set the p-break and still couldn't see them open. Fact I've never seen them open wether running at idle or parked shut off.

Doubt the ECM will open them with the vehicle stationary. There is sufficient air flow from around the front of the radiator for the fans to pull through the radiator. Don't know if the ECM looks at vehicle speed as one of the inputs. If it does not, you may be able to unplug the cooling fans to trick the ECM into opening the shutters. Note that you must not do that and run the a/c at the same time. It will likely damage something due to excessive high side pressures. I once had a customer bring in a mid 70s small car with aftermarket a/c. The shop that installed the a/c left the original 2 blade engine fan on it, and it would burn the a/c belt off at traffic lights due to high side pressures so high it stalled the compressor.

tbarn · December 14, 2017

I fail to understand the concern. If it fails, you WILL get a SES light. No light.... No problem.

Crobinson16 · December 14, 2017

3 hours ago, tbarn said:

I fail to understand the concern. If it fails, you WILL get a SES light. No light.... No problem.

Consern? Oh yeah that's right, no trouble shooting needed , everything has a sensor. Give me a break. Any sensor or electrical device can read incorrectly or not accurate parameters and not set a SES, letting the system think it's operating correctly. If the given parameters are met and the shutters don't open then yes a light would be set, but if it doesn't tell the shutters to open because it doesn't provide a correct reading, then no it's not going to set a light.

Edited December 14, 2017 by Crobinson16