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Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.
Did you have the fault codes checked at all using a scan tool that can plug in and communicate with all computers on your model here?
Let me know so we can continue,thanks Pete.
O.k.,is the add coolant and BAS lights all coming on at the same time here when this occurs and do they go off when the issue is not occuring?
O.k.,you will need to have the fault codes checked/read out to see what codes are set.This needs done with a scan tool that is fully compatible with your model here.Once this is done the codes can then be diagnosed to locate and repair this fault here.I have seen the ME (engine computer) fail and cause this issue here and in some cases can be all of the time or intermittently.It is rare to fail but it does occur.
The coolant level sensor may be at fault here and this may be causing the fan to run if the computer thinks the engine may start to run hot due to low coolant even though the coolant level is o.k.I have had to replace the coolant reservoir in the past before for the false low coolant message.I would start with having this checked to see if this resolves all of the issues here.
The BAS is a brake fault.The codes need checked/read out of the brake computer to help locate the cause for the BAS light and then repaired from there to correct this issue.
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Unfortunately I do not show a test procedure for this myself here.I think if you unplugged it it would still show low coolant level so I dont think this will help.I believe it is the dealers SDS machine plugged into your model is the diagnostics that help.it usually walks you through or the technician through testing this here to make sure it is the sensor at fault.
Let me know if you need anything else and feel free to rate my help here as this is how I receive credit for my time.
The sensor is in the reservoir as shown below.
Unfortunately I do not show a manual way to test this sensor myself.Usually it is checked/tested with a dealers SDS machine or a compatible scan tool.