P0335 code, will not start

Thanks for the detailed answer. (I had a typo that I assume didn't throw you. It is P0335 without the 9.). I did what your guide told me. Measured the speed sensor for about 300 ohms and found the 1.8 volts above ground on both leads. All the wiring looks fine. So today I put in another ECU from a salvage yard and it didn't change the codes. For the record, the codes fluctuate as I do experiments and sometime only one or two of the three codes comes up. Makes it more confusing. For example I changed the Cam Sensor and that code went away for a while and I only got the 335 and 336 codes. Now I have all three. P0335, P0336, and P0341. By the way, the engine does not run at all.

Sure enough the diagnosis is in. The timing belt has slipped and the sensors are doing their job of not letting the engine start. My guess is the tensioner is broken. Will find out when I get more of this apart. The compression was low on all four cylinders and I noticed the lack of tension in the belt. Must be the tensioner.