Yes, this is true that your son's insurance company can deny the Collision claim since he has Limited Collision coverage which does not pay out if the driver is more than 50% at fault in the accident. Falling asleep at the wheel of the car and having an accident is normally found to be the driver's fault since they lost control of the car and had the incident.

In Michigan if you are MORE THAN 50% at fault (you hit a tree, a person, another vehicle, etc.) and have Limited Collision coverage your insurance pays nothing. You are responsible for the cost of repairs to your car. If you are 50% OR LESS at fault (you are rear-ended, side-swiped, etc.) your insurance pays. If you have chosen a deductible, your insurance pays the cost of repairs over and above the deductible. You must pay the deductible.

When you are MORE THAN 50% at fault and you have Broad Form Collision coverage, your insurance pays, except the deductible that you have chosen. You must pay the deductible. If you are 50% OR LESS at fault, your insurance pays. You do not have to pay the deductible.

So while your Broad Form Collision coverage would normally cover if you have an accident in your car and it was your fault, you would owe your deductible amount though, it is doubtful this coverage will extend to you driving your son's vehicle. Typically physical damages of Collision and Comprehensive do not extend to other vehicles you drive. This is mostly done since you could drive say a Ford Escort but borrow your son's Mercedes. The rates you are paying for these coverages are for the much cheaper Escort and not a Mercedes which is much more expensive to repair.

Even if your car is on par with your son's insurance companies do not usually extend your Physical Damage coverages to someone else's car so if his Limited Collision coverage turned down the claim due to you being more than 50% at fault (likely they found you to be 100% at fault since you fell asleep at the wheel and had a single car accident).

You can however contact your insurance provider to find out if they will extend your Broad Form Collision coverage to your son's car since you were driving the car and caused the damages. Your agent will tell you for certain what the company's guidelines and the terms of your policy say about this situation. If your insurance does not pay out either than unfortunately that leaves you being personally responsible to your son for the damages to his vehicle.

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