My 1991 eldorado biarritz has a problem. While driving car, the heater will suddenly stop, dash board switches to miles instead of kilometres, trip odometer stops working, odometer stops working until I shut off the car and then restart the car and everything is fine. Now another problem, I cannot start the car. Can anyone please help me and tell me what may be wrong? This car only has 75,000 km.
thank you

Check the easiest first. A bad battery can make these cars act as if they are posessed. Check the battery and connections first.

Check for codes, will Onboard work when condition occurs? Need more about no start. If battery is not the cause.