Xsara2 AL4 auto fault code - solenoid short to positive

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Haakon
Posts: 21
Joined: 18 Feb 2011, 12:39
Location: Melbourne, Australia
My Cars:

Xsara2 AL4 auto fault code - solenoid short to positive

Post by Haakon »

Brand new transmission, new everything (all sensors, solenoids etc, converter...) will after some time on a motorway unlock its converter and stay unlocked until a restart.

Fault code it throws it either intermittent or permanent short circuit to positive for either or both of the converter lockup and pressure modulation solenoids.

Ive had the engine loom apart and visually inspected the wires, all good. Multimeter tested the resistance values for the solenoids, all good (well, they are brand new...). New valve body loom too.

in short, the short appears to be phantom. Anyone seen this? ECU a bit schizophrenic perhaps?
Haakon
Posts: 21
Joined: 18 Feb 2011, 12:39
Location: Melbourne, Australia
My Cars:

Re: Xsara2 AL4 auto fault code - solenoid short to positive

Post by Haakon »

If I start the car and leave it idling in park for a few minutes, it will go into limp mode and flash the snow/sport lights. Teh code with be the intermittent fault pressure modulating solenoid short circuit to positive.

When the torque converter lockup lets go, the code it throws is intermittent fault lockup solenoid short circuit to positive.

Sometimes, one will come up as a permanant fault.

Let's assume for a moment that the brand new BW solenoids and the brand new valve body loom (which I've tested with an ohmmeter anyway...) are ok. That leaves software/ECU...

I have been told the software has been updated for the BW solenoids. But what is the likelihood of this havin not been done right? Or more accuratly, what would happen in a car with old software and BW solenoids?

The short to positive from either of the solenoids seperatly, which share a common positive supply from the ECU, says to me that the ECU is seeing a resistance in the solenoids it's not happy with. Usually that would say suspect solenoid, but am thinking maybe it's not happy with the BW solenoid?

Time to try another ECU methinks....
Haakon
Posts: 21
Joined: 18 Feb 2011, 12:39
Location: Melbourne, Australia
My Cars:

Re: Xsara2 AL4 auto fault code - solenoid short to positive

Post by Haakon »

Today I had the lexia plugged in and showing parameters when idling, and caught the PMV fault as it happened.

The selected pressure was 2.7 bar, and the oil pressure wandered up and down a little from 2.45 to 2.7, spending the most time around 2.6. Seems about right I suspect.

Then for apparent reason, selected pressure flipped to 21(!!) bar and the oil pressure went to 3.4ish. Snow/sport lights flashed, and the short to positive fault code logged.

That's damn odd. Now. Where does the selected pressure information come from? Is this a calculated figure straight from the ecu?

Why would it suddenly decide it wants 21 from 2.7 when just idling in park?

All other parameters on that page were normal, so no speed sensor issues I think. Throttle position stayed at its normal 6% at idle...
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