Hondata

I have a buddy with a '02 Civic SIR and K-Pro. Recently his car has been throwing P1259. He topped up the oil, cleared the code, and it comes back.

We started tracing the wiring to the VTEC switch and found the ECU is not raising the pin (B1) to 12V. In the ON - II position, the pin read 0.02V. When the engine is running, it's between 0.20V and 0.50V.

Tired reflashing the ECU and upgraded to the latest version of KManager.

For now we turned off the VTEC oil pressure switch in Parameters->VTEC so he doesn't have to limp around.

Is this something that could be caused by software? If not, can we externally wire up a 100K resistor from +12V to the switch input to force a pull up voltage?

Is this something you have seen before?

It is an input pulled high by hardware - the software can't affect it.

Check the ECU to see that nothing is obviously broken or burnt, but I would guess the most likely cause is a broken or shorted wire to the pressure sensor. The easy way to test this is to put the ECU into another vehicle. It could also be that the internal 5V supply used to pull the input high has been shorted to ground somewhere else, so check the VCC outputs also.

Hondata wrote:It is an input pulled high by hardware - the software can't affect it.

Check the ECU to see that nothing is obviously broken or burnt, but I would guess the most likely cause is a broken or shorted wire to the pressure sensor. The easy way to test this is to put the ECU into another vehicle. It could also be that the internal 5V supply used to pull the input high has been shorted to ground somewhere else, so check the VCC outputs also.

Yeah, i'm pretty sure we did check the wire to see if it shorted or was broken. I'm trying to find someone now that has an EP3 in my area to test out.

The same thing happened in my K20A3 in my DC5. I would drive around and then all of a sudden the code comes up and my car goes into limp. The oil pressure slowly drop to just about 19/20 when the car is warmed up.(I have a Oil Pressure gauge)

It was like that for 2 months. I changed the VTC swtich and gasket and that didnt work. I Never could trace the problem.

It happened after the car bottomed out really bad on the freeway.

So long story short the problem just went away....i think it was either something electrical or the ECU, but i cant be certain.