Error Fault Code 12

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Lextreme

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Has anyone figured out what is the reason for code 12 fault?

Original 1uz-fe ecu. The code says rpm signal fault. Replaced crank sensor and cleaned cam sensor no change.

How i came about this issue is as follows. I tried starting the car and the starter wouldn't turn over. I removed the intake to get to the starter and tested the B postive wire from battery it was fine. I tested the signal wire to the starter relay. It had no continiouity. I then laid my own wire to the relay and the starter turned over but engine wouldn't start as it did not get fuel.

The original wire somehow also gives fuel pump a signal. I then connected the original wire to a relay next to the starter relay and it started but the engines performance is very poor. Does not rev up like it should and backfires when decelerating.

Help would be much appreciated.

Posted for @bennie1023
 
The Factory ECU only allows the fuel pump to run whilst it has an ignition signal.

The code 12 suggests it doesn't have spark, so no fuel.

Time to start looking at Igniters plus ensure they are getting power when cranking.
 
For code 12 it says engine revolution signal missing.
Since you changed the crank sensor, and cleaned the cam sensors, you can check the wires going to them, since one of the cam wires comes near the accessory belt.
Also, in the wiring diagram, it says that the white wire on the engine speed sensor (crank sensor) is connected to both cam sensor plugs. Both cam sensors have the white wire too. So I would make sure that that the wiring on the front of the engine is intact.
 


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