L322 '07 tdv8 multiple faults, electrics related

Hi all,
I'm in trouble here. The following issues all appeared at the same time:
- Steering wheel does not return when ignition is switched off
- Steering is as it should be for the first few seconds after starting, then goes heavy as if the speed-sensitive assistance is told I'm going fast.
- One-touch window opening non operational (one-touch window closing still works)
- Steering lock fails to engage / disengage with the insertion/removal of key
- Remote central locking "forgets" the key signal. Resets after disconnecting / reconnecting car battery.

All the faults mentioned above occurred at the same time on the same morning a few days ago. Since then I have had to disconnect the battery a number of times to get the remote locking working. A couple of times this has also cured the heavy steering, but only for the first trip after the disconnect / reconnect. It always returns to heavy after a stop / start sequence.

Two days ago, the battery was flat when I went to start in the morning. Charged overnight and next morning everything was back to normal, but only until I stopped the car, when the steering column failed to retract. On this occasion, I noticed that the wheel did retract a few seconds after I locked the car by remote. That only happened this one time.

I have checked battery voltage and charging voltage. With everything off, battery is 12.6v. After engine start, it is 13.0v, then climbs to 14.5v after maybe 30 secs. After a run, with engine ticking over, it sits at 13.4 - 13.6v. A bit low?

I'm suspecting an alternator diode, ignition switch or noise suppressor, but really I don't know.

Have any of you had similar or identical behaviour from your rr, and what fixed it?

Thanks!
Henrik

You should be looking at 14.9v ar 2000rpm with lights and everything turned on, this the first cheap but suspect the alternator is dodgy it may well be just the diode as you suspect.

Cracked it!
As implausible as it sounds, all faults were caused by the webasto FBH. I tried to think of what events took place before the faults first occurred, and I could only come up with one: I had replaced the FBH shortly before. The original one was smoking badly and kept going out, so I bought a used one off ebay, overhauled it and installed it in place of the original. It worked perfectly. I did notice that it had been removed from a different vehicle, an X5 I believe, but it did everything it should. Yesterday, after trying most everything else, I dove in and disconnected the cables from it, put the battery back in the car and hey presto! Everything back to normal. The list of things that were affected is long:
- Steering lock failing to engage / disengage
- Steering wheel not retracting after engine shut-off
- Power steering heavy
- One-touch driver's window lift inoperative
- Remote lock/unlock intermittent
- Wipers on timed interval in 1st and 2nd pos on the stalk, slow continuous on 3rd. Correct operation is 1: rain sensor, 2: slow cont., 3: fast cont.
- Battery drain in 2 days
Probably some more I can't think of at the moment.
It doesn't make any sense at all, but it is what it is.
So, if you have odd problems which the dealer fails to diagnose and cure, try disconnecting your FBH before you start throwing parts and money away.

Cheers,
Henrik

Henrik97 said:

Cracked it!
As implausible as it sounds, all faults were caused by the webasto FBH. I tried to think of what events took place before the faults first occurred, and I could only come up with one: I had replaced the FBH shortly before. The original one was smoking badly and kept going out, so I bought a used one off ebay, overhauled it and installed it in place of the original. It worked perfectly. I did notice that it had been removed from a different vehicle, an X5 I believe, but it did everything it should. Yesterday, after trying most everything else, I dove in and disconnected the cables from it, put the battery back in the car and hey presto! Everything back to normal. The list of things that were affected is long:
- Steering lock failing to engage / disengage
- Steering wheel not retracting after engine shut-off
- Power steering heavy
- One-touch driver's window lift inoperative
- Remote lock/unlock intermittent
- Wipers on timed interval in 1st and 2nd pos on the stalk, slow continuous on 3rd. Correct operation is 1: rain sensor, 2: slow cont., 3: fast cont.
- Battery drain in 2 days
Probably some more I can't think of at the moment.
It doesn't make any sense at all, but it is what it is.
So, if you have odd problems which the dealer fails to diagnose and cure, try disconnecting your FBH before you start throwing parts and money away.

Cheers,
Henrik

Click to expand...

Shows the folly of linking unrelated systems together via a common data bus.

Dead on! This is the sort of stuff that can drive you totally bonkers. I went to two different workshops, one indy and one dealer, and I could tell they hadn't the faintest clue where to start looking. When a factory-trained LR tech is thrown off that easily, you know that the training is insufficient, or the car is just too effing complicated. I'm leaning towards the latter.

H.