You need to trace the wires fro the circuit and check them out. Make sure signal is getting from point A to point B. Make sure you have a good connection.
I had a customer with a similar problem. Took his car else where, to the tune of $1000 worth of parts changing. I found the problem in 3 hours of testing. A bad wire connection at the DIS connector. I temp fixed it, and told the customer to drive it for 2 days. The amount of time I was told it would take to get the connector in at the dealership's parts department I went to.
The customer is still driving on that temp fix, leaving me out for the new connector I bought. Charles