SL320 1999 Does not want to run after flat battery

[alan ainsworth]

Got a 1999 SL320 battery went totally flat 0.61vdc. Vehicle now runs after a jump start but with major probs.

no response to the throttle.
engine running very rough.
dash lights showing roll bar active but its not.
electric hood switch showing active/partial open but its not.
electric windows totally inoperative.

I feel the vehicle may have fault codes stored and needs a MB reset.

Any ideas?

 

[joe bloggs]

Check these (any order)
1 Check overvolt fuse under big plastic panel, n/s under bonnet (5? screws)-known to blow after a jump (dont we all)
2 ignition on , slowly fully open/fully close throttle at pedal (to re-teach throttle position to ECU)
3 Try driving car round a bit, roof / roll bar need logical roadspeed/ steering angle signals to function (often happens when battery has been flat, or car has been hanging on a wheelfree ramp with only 2 wheels turning.
4 Re-teach windows - note that the switches have a double action - push slightly the windows work normally, push fully and they auto work - if they work on the first position then fully open / pause / close them on this position (without stopping halfway) and the auto function should recover - this has to be done before the roof / roll bar will work.

5 Have a cup of tea
6 Hope no-one was silly with the jumpleads and connected them up arse for tit.
7 Check fuses in boot on o/s upper edge, for windows/roof etc.
8 My money's on the overvolt fuse(s), you are looking for a silver relay with some fuses on the top under a clear plastic cover, the relay may have a black plastic cover over it.
9 Still thinking...

 

[alan ainsworth]

320SL Not well after jump start

Thanks Joe(?) retaught the throttle to ECU now runs fine, the hood,rollbar, window situation is as was. At least we can now use the car. I have checked all the points you mentioned but can find no faults. I presume the windows are interlinked to the hood/rollbar somehow?

 

[Arnie]

Yes, the hood and window mechanisms are operated by the "body electronics" control box. You may have blown a fuse that supplies this box. Check the OVP relay again, as mentioned above. MB electronics are very sensitive to battery voltage. You've found out the hard way, but in future, if possible, it's best to recharge a battery with a trickle charger overnight rather than risk all these problems. (If you have BAS/ESP, you will also need to turn the steering from lock to lock if you see the warning light, to reset this system.- Strange, though, if you have BAS/ESP and did not get this warning?? It's probably the most sensitive system.)

Incidentally, the rough idling means that the ECU has lost its memory and will have to relearn the idling parameters, starting from base values. This is normal and should be ok after a running the engine for a while.