P0026 & P0028

[ericinboca]

2004 986S special edition

I got error codes P0026 & P0028.

I checked the voltage to the solenoid hydraulic valve pin 1 and ground - it was fine.

I checked resistance of the solenoid across its two pins - it was fine.

I want to check the continuity of the triggering wire. It says measure resitance between III/1 on the wiring harness module and solenoid connector pin 2. Connector III is the third one down right? The one with the mark on the mounting plate that says 3....the 52 pin module connector.

If I have the right module connector, there is no wire coming from the harness into the pin 1 spot on the connector module.

Then I noticed the diagnostic says the wiring for the solenoid hydraulic valve is routed via the connector X 59/2 pin 8. I have no clue what that is.

Anyone know what is going on here?

[Loren]

Hmm... valve lift control fault on both banks at the same time. I think highly unlikely. I would clear the codes and see if they come back.

[ericinboca]

I can't make these codes go away. Still have them in both banks. 2004 986S

Is this the connector for the hydraulic valve control solenoid, or is this the oil level sensor, or the camshaft sensor?

I also see another sensor farther aft, but it looks like a speed sensor. I think I am looking at the camshaft sensor, which I guess doesn't really help me determine if anything is wrong electrically or mechanically with the solenoid.

I gather the solenoid valve is "inside", so I am not even sure there is an external connector. Do you have to remove the valve covers to really check out the solenoid pin resistance, voltage, etc. as outlined in the diagnostic check?

When I use Durametric drive links and "activate" control valve lifter bank 1 & 2, I do not hear anything, or find anything different in how the motor runs.

http://photos.streetfire.net/photo/1690767.htm

[Richard Hamilton]

I'm not sure I can help much, but connextor X59 is a 21 pin plug/socket, located near to the DME control unit in the rear trunk. I got this from sheet 23 of the wiring diagrams, which shows the grid location of all the connectors.

[ericinboca]

I'm not sure I can help much, but connextor X59 is a 21 pin plug/socket, located near to the DME control unit in the rear trunk. I got this from sheet 23 of the wiring diagrams, which shows the grid location of all the connectors.

Thanks Richard. I traced the two wires from whatever connector I am looking at back to the rear trunk, through X59 and was able to determine continuity on both. Starting to understand some of the names of things on the wiring diagrams.

I just don't know if I am checking the sensor, which would mean I am not checking the real problem, or if I am checking the valve. I think the valve is under the cam cover and cant be tested for real without removel of the cover. Just not sure.

[Richard Hamilton]

The picture you posted is of the Variocam Solenoid Valve connector, so you are looking at the correct connector. As Loren says, extremely odd that the fault is on both banks.

[ericinboca]

The picture you posted is of the Variocam Solenoid Valve connector, so you are looking at the correct connector. As Loren says, extremely odd that the fault is on both banks.

If I apply 12 volts directly to the pins on the valve, if it was working, shouldn't I be able to hear it clicking? When I tried this, I could hear the electrical spark, but even with a stethoscope, I could not hear any clicking internal, and Durametric drive links didn't seem to make them do anything either. There is continuity across both pins on the valve, the connector gives me battery voltage, and the triggering wires are continous back to the DME and to the relay.

Looks like both valves have a relay in common - I swapped out the relay with an identical one in the box and still didn't get any result.

The DME is new - new hardware, and identical software as the original.

I left thinking they both are gone - strange, but I suppose possible.

[wvicary]

What resistance value do you read across the solenoid?

[ericinboca]

What resistance value do you read across the solenoid?

11.8 Ohms with the motor warm, not hot...just warm.

After it cools off in a hour or so, I will give you the motor cold reading.

[ericinboca]

What resistance value do you read across the solenoid?

11.8 Ohms with the motor warm, not hot...just warm.

After it cools off in a hour or so, I will give you the motor cold reading.

Resistance across the solenoid pins, now that it has cooled down a lot, is showing 11.4 on both valves. According to my manual, that is within spec.

Here is another bit of likely important info.

I got these codes after putting in a new DME. New hardware and new software. My DME guy (reputable) swears he is certain he has the right version of software on the DME - that it is VIN specific, and eventhough I have a special edition 986S that has some slightly different bits and pieces in the motor (intake is actually a 987 intake), there is no problem in the DME.

I talked to him today about this fault code, along with a PSM fault code, and he argues these codes are not uncommon with a new installation, and that sometimes Durametric cannot clear them - that it needs be cleared with a PST2.

Anybody buy that theory?

Edited May 18, 2009 by ericinboca

[ericinboca]

Just closing the loop on this thread...

You will note above that these fault codes showed up after replacing the DME. Turns out the creation/flashing/choosing of the maps for the new DME did not go exactly right and triggered these codes. Reprogrammed correctly and all is right with the world.