Non start,self diagnosis on the control unit code 21 no ign signal

Start signal comes from the clutch engagement switch. When you press the clutch the pedal arm hits a switch and signals the motor to be able to start. Look and see if you have a little rubber piece pushed through a hole on the clutch pedal arm

Try the crankshaft sensor

call any auto parts store and they will tell you, the gap for non turbo 300zx.

About the only thing left is the Ignition Control Module.

My vg30 dnt rev more than. 2200

the throttle position is bolted on to your throttle body, you should check your air flow meter also, the ecu, located behind the passenger kick panel, has a self diognastic mode with all the code definitions listed on the ecu, if i remember correctly turn the key on , dont let starter engage, pusk gas pedal to floor, release, then the ecu will bling red and green, two red blinks and one green means code 21 and so on

The self-diagnostic system identifies malfunctions of signal systems such as sensors, actuators and wire harnesses based on the input signals received by the ECCS control unit. Various malfunctions are coded and displayed on the control unit by a series of blinking red and green lights. Results of the self-diagnosis are retained in the control unit's memory and are displayed when the mode selector, located on the rear of the control unit, Fig. 122, is switched to the On position. When displaying malfunction codes, the code number can be determined by counting the number of light pulses. The red light represents the first digit of the code, while the green light represents the second digit of the code. For example, a Code 32, would be displayed as three flashes of the red light, followed by two flashes of the green light. Malfunction codes can be translated as follows:

1. Code 11 -- Crank angle sensor circuit malfunction.
2. Code 12 -- Air flow meter malfunction.
3. Code 13 -- Water temperature sensor circuit malfunction.
4. Code 21 -- Ignition signal malfunction.
5. Code 23 -- Idle switch circuit malfunction.
6. Code 24 -- Transmission switch and clutch switch circuit malfunction.
7. Code 32 -- Starter signal malfunction.
8. Code 42 -- Throttle sensor circuit malfunction.
9. Code 43 -- Injector circuit malfunction.
10. Code 44 -- All monitored systems satisfactory.

Don't get too concerned yet. Take it to the shop and let them scew in a well know mechanic's gage to make sure that the sensor isn't giving you a bad signal. That would be the first place to check.

The starter should fit either an automatic or manual.

do u think it might be the differential