When I put it in drive and am holding the break. The transmission shifts to 2 and the speedometer goes to 30 mph when my heater is on. But if I turn the heater off then it's perfectly fine. My transmission is automatic bit also have the ability to switch to manual with slap stick.
My car has an automatic transmission.
It sounds like the speedometer circuit and the shifter circuit may be shorted together. The shifter movement should have no effect on the speedometer needle. I would recommend having an electrical componenents are not working inspecton performed to locate the short in your shifter circuit. This may include the use of wiring diagrams and a digital multimeter. Consider YourMechanic for this inspection as it can be completed convieniently from your home or office.
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