Hello all,

I'm working on a 00 accord f23a4 which is setting a P1259 / vtec code, here's the problem I'm having...

After checking the system operation, (pressure switch with computer ref voltage present, proper ground at the connection, proper solenoid operation), I then reset the MIL only to have the light come back on about 3 seconds after resetting it. This is with the ignition "on", engine "off".

I could understand if there were a vtec system's problem, after resetting the MIL and running the engine the computer would sense a problem and set the p1259 code but the MIL is triggered "on" about 2, to 3 seconds after resetting it with the engine not running.

Another issue which may point to a wiring or computer problem, with the vtec pressure switch connected, the condenser fan is triggered "On". Not sure this is a normal mode of operation.

History on this vehicle, the engine was overheated to the point, all of the plastic timing covers were melted. The past owner did say a MIL was on which he had scanned and was P1259.

Any insight offered would be appreciated,

Thanks!

 

Did your system checks include following?

1) Check that pressure switch has continuity across 2 switch pins w/ harness disconnected.

2) Check that battery voltage is available at Pin 2 (blu/blk wire) w/ ignition switch on, and also battery voltage between pins 1 and 2 of connector. If not, ground is missing on pin 1.

3) Check that disconnected Vtec solenoid valve has continuity between single pin of solenoid and ground. Resistance should be 14-30 ohms.

If those are OK repeat tests 1) and 3) from PCM connector C (disconnected from PCM) for pressure switch wire (Pin 10 Blu/Blk) and solenoid drive wire (Pin 3 Grn/Yel).

If both check OK again at PCM connector, then PCM is likely fault.

good luck

 

Hello TexasHonda,

Basically yes, all checks out. With computer reference voltage present at the pressure switch socket connecter pin, (12.6 v engine off, 14.6 v running), and ground / negative reference on the other pin.

Continuity / closed reading at the pressure switch pins in the off mode, and open reading when pressure is applied.

17.5 ohm reading at the solenoid lead.

With a pressure gauge installed in the block's oil pressure switch port , I removed the Vtec assembly and ran some pressure tests at the cylinder head port and both readings were the same, (70 lbs cold, 18 lbs hot).

Next, with the Vtec assembly installed, I checked for oil pressure at the Vtec switch port and had zero at idle, and full pressure with battery voltage applied to the solenoid so it seems to be working correctly.

I think you may have a point about a possible computer issue. What's happening is, I reset the MIL with ignition on, engine off and before I even disconnect the scanner and start the engine, (within a few seconds of reset), the MIL is triggered on again with a p1259 code.

Another point, with the ignition switch on, both radiator fans run continually and shut down when I disconnect the Vtec assembly port switch...not sure if this is a normal operating mode?

Thank's TexasHonda,

any other thoughts you might have please pass them along!

 

Ok, I haven't gone off the deep end in a while.

Can't find a good pic of the vtec oil pressure switch - is it possible that the cooling fan plug and the vtec oil pressure plug got switched during the engine install?

 

Ok, found it - helps to look on the correct page in the book

The plugs do look the same - what color are the wires that are plugged into the vtec oil pressure switch?

 

Hello poorman212, thank's for the post.

Both Vtec connectors, solenoid and pressure switch, are gray in color and pressure switch wires are "black and solid green" with battery voltage reference at the green wire when ignition is on.

Solenoid wire is "green with a white, or yellow strip".

The coolant temp switch / sensor connector on top of the thermo housing is green.

Thermo housing switch / sensor wires are solid "orange and black" with black wire reading battery voltage when ignition is on and orange reading ground.

(BTW, yes, both connectors look exactly alike with just the colors being different.)

Connecting the Vtec switch or with a jump wire, both fans run.

Connecting the coolant switch or with a jump wire, nothing happens.

Think I'll invest in a manual, Haynes or other, but any info you can think of would be helpful.

Thank's again!

 

The radiator fan switch (located on the thermostat housing) is normally a 2P green connector with one green wire and one black wire. The black wire is suppose to allow the ground to go through to the green wire when the switch is closed (jumping the harness connector essentially does the same thing, to allow the ground to go through).

When you refer to the "Thermo housing switch / sensor", are you referring to the radiator fan switch or something else, since you stated it has orn/blk and blk wires and battery voltage reading on one side?

 

Hello redbull-1,

Yes, I was referring to the sender on top of the thermostat housing. Wasn't sure if it was a switch or heat sensor, "thermistor". A switch does makes sense though, there's an open reading across the switch pins vs. a resistance reading.

The connector to the thermostat housing, the one that was originally connected when I received the car, is green in color, and the wire colors are orange and black. Black wire is the one reading positive battery voltage with the orange wire reading negative ground.

Nothing happens when I jump this connector.

Vtec connector sockets are both gray in color with the switch connector wire colors being black and solid green. Green wire has positive battery voltage and black, negative ground.

Jumping or connecting the gray socket triggers the fans on. Both thermostat and vtec switch sockets do interchange so I might switch the connections to see what happens.

If the fan switch wire colors are supposed to be green and black, what are the vtec switch wire colors supposed to be?

Thanks redbull-1!

 

Regarding a manual. Suggest purchasing the Honda shop manual from automanualsource.com for $22. This is an excellent searchable and menu equipped manual.

good luck

 

Thank's TexasHonda, I'll check this one out!