Possible causes – The circuit between ECM and A/T control unit is open or shorted– Faulty Engine control Module (ECM)– Engine control Module(ECM) harness is open or shorted– Engine control Module (ECM) cicuit poor electricl connection– Faulty Automatic Transmission Module (TCM)– Low battery voltage– Automatic Transmission Module (TCM) harness is open or shorted– Automatic Transmission…