For any frequency above a 100Hz or so, the meter will just measure the average value, so you won't see an meter movement. Measure the voltage at the collector of the 2N3055 to ground. It should be well above 12V if the device is operating due to the inductive spikes from the ignition.
Of course with no zener diode protection for the transistor, those inductive spikes may very well have blown it.
The average DC output voltage at pin 3 on the 555 should be about 6V when the 555 is oscillating.
The base of a bipolar transistor is normally only about 0.7V when on.