![]() ![]() The only way VTEC PRESS SW = ON when we have disconnected the vtec pressure switch connector is if we have a short to ground on the BLU/BLK wire or a short to ground inside the PCM. In an open circuit the BLU/BLK wire will measure 12v and we have artificially made the VTEC PRESS SW = OFF. Well, if we disconnected the vtec pressure switch connector, we have made an open circuit. Then in step 8 it says, check to see if VTEC PRESS SW = ON. Disconnect vtec pressure switch connector. That’s all basically checking oil level and confirming the P2646 is still present. Ok, now that we are on the same page, take a look at the P2646 algorithm listed. Potential causes of P2646 would then either be:ġ.Computer shorted to ground at BLU/BLK pin, abnormally reading 0VĢ.BLU/BLK wire shorted to ground, abnormally reading 0vģ.vtec pressure switch stuck in closed position, always in continuity, 0vĤ.vtec pressure switch not getting sufficient oil pressure to open the switch, such as in a a) bad solenoid not opening, b) clogged vtec spool valve screens, or c) low engine oil pressure (from a multitude of causes) In English, when the PCM activates the solenoid, it expects the vtec pressure switch to respond by saying it sees pressure. To say it in a different way, if we ever have a situation where VTEC SOL=ON and VTEC PRESS SW=ON, that means a P2646 code will appear. ![]() P2646 is vtec pressure switch circuit LOW, which means that the computer was expecting 12v on the wire, but got 0V on wire. VTEC SOL = ON, 12v on GRN/YEL wire, VTEC PRESS SW = OFF, 12v on BLU/BLK wire. VTEC SOL = OFF, 0V on GRN/YEL wire, VTEC PRESS SW = ON, 0V on BLU/BLK wire. This causes the PCM to read 12v on the BLU/BLK wire.Ī scanner will read the PCM data VTEC SOL and VTEC PRESS SW. When the VTEC solenoid opens and sends sufficient oil pressure to the VTEC pressure switch, the switch opens (becomes discontinuous), and the BLU/BLK wire path to ground through the BRN/YEL becomes disconnected. Since the wire is grounded, the PCM reads 0V on the BLU/BLK wire. The BLU/BLK wire carries 12v from the PCM to the VTEC pressure switch, which is in a normally closed position (continuity) allowing the voltage to be routed through the BRN/YEL wire to G101 ground. The VTEC solenoid activates and sends oil pressure to the VTEC pressure switch. ![]() When the PCM wants VTEC, it sends 12v (EDIT - this is a square wave power signal, so it probably does not read 12v on a multimeter) onto the GRN/YEL wire to the VTEC solenoid, which is grounded to G101 through a black wire. Now that everyone can see what I’m referring to, I’ll start by describing the VTEC system as I best understand it. ![]()
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