temporary start problem

[steenschalls]

Sometimes my C5 2.0 HDI 2006 will not start at once, but needs 3 or 4 attempts. Lexia failure code is U2000, main wake up call. What does this mean and what can I do to solve the problem?

regards
Steen Joergensen

[GiveMeABreak]

Remote controlled ECU wake-up: Partial wake-up request absent or not valid

That means that a remote request to wake up certain ECUs did not happen or was invalid. An example is if unlocking the car with the fob, the BSI will start telling come of the ECUs to wake up in anticipation of you starting the car. For one reason or another (there is no specific reason given as it can be from any of the RCD wake up calls) some ECUs were not brought out of their sleep state into readiness.

A cause of this can be a weak or discharged battery.

I suggest you follow this procedure and get the battery off for a good overnight trickle charge: At the same time it will also reinitialise the various ECUs to make sure they shut down and re-awakened correctly.

BSI Rest / Battery Disconnect / Reconnect Procedure

In your case it may have caused a delay with the transponder getting the signal through the BSI to the engine ECU to authorise a start.

[steenschalls]

Lexia says Batt voltage before start 10.64V, after start 12.35V ( too low ?)

regards
Steen

[GiveMeABreak]

Yes too low.

It should be about 14.3 - 14.7V for charging with engine running and at least around 12V at rest - but remember to open the bonet, but keep all the doors shut and wait 5 minutes for the BSI to shut everything down before measuring (with a multimeter is best) otherwise there will be some current being used by the ECUs when being interrogated by Lexia.

So I don;t know how old your battery is - but if older than 5 years I would suggest it is past best - especially with these cars that have a lot of electrical systems.

Try giving it a good charge overnight anyway, and see what you are getting with the a multimeter across the terminals after it has being charged and back on the car. If it is not charging at over 14v then you may find that the battery is at end of service life or there may be a fault in the charging circuit (alternator / wiring / earth). Also check out and clean the battery terminal posts and cables.

[moizeau]

That sounds like a cell down, this also means that the dead cell saps the power from the good cells faster. Charge the battery overnight, check the voltage with a meter (battery not connected to anything) then leave it for a day (still not connected to anything) then retest with the meter. There shouldn't be a significant drop in volts between the two meter readings. This will confirm if the battery is good or not. Hopefully it's no good as it's the easiest fix.

[steenschalls]

Thank you for your remarks. I will go ahead with charging and testing the batt

Steen

[Kennyd90]

If it still doesn't start properly, you may have a worn out starter motor. All the Hdi engines I've had did need new starter motors. As the starter motors wear out they get slower and slower and they get to a stage that they will struggle to turn the engine over fast enough for it to start.

[steenschalls]

Hi again

Info to battery.
After a long run, batt disconnected12.97V, 24 H later 12.92V
Batt connected 12.62V, 24 H later 12.45V
Now normal start, (first attempt)
The starter motor runs nice, fast and with no noise
I will check the Batt voltage next time I have the start problem

regards Steeen

[steenschalls]

Hi again

Now this morning I had the problem again. Only starting in second attempt. Batt Voltage 12.64, and no fault in Lexia this time? No big deal but why do I have these temp start faults?
regards
Steen

[Peter.N.]

The starter on mine is very slow, it does start ok though. I checked the battery with a load tester yesterday and its reading very good although it looks quite old so I'm pretty sure that the problem will be with the starter, if yours turns over quickly it won't be that of course.

These starters are of the high speed motor - geared type, I did once take one apart and found the gearbox virtually dry, I added some oil and grease and it was like a new man, that was on an XM but same sort of motor.

Peter

[steenschalls]

The starter is fine