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Hi Guys
Just recently, my 2005 SL350 does not show the 'P' & 'C' indicators in the right hand dash display. When this happens, it also 'thumps' into gear when placed into drive and then, will not go past neutral from Drive until the engine is switched off where it can then be put back in Park again. If reverse is selected, it does the same and 'thumps' into gear. If Drive is selected, it will stay in (what I think is) 2nd gear and will not change up.
If the engine is left idling for a few minutes, switched off, key removed and ignition switched on, 9 times out of ten, the 'P' and 'C' indicators come back and the gearbox behaves normally. I initially thought this was a voltage problem as the incorrect consumer battery had been fitted so a brand new Varta AGM battery was obtained and fitted but this did not cure the problem. Further checks showed that I could still get the 'P' and 'C' indicators even when the voltage was getting down towards 12V and conversely, not always get them when the battery had been fully charged. This is as far as I've got at the moment and haven't had chance to get the codes read as yet. An internet search did come up with a company in Australia that repaired gearbox modules which looked to be in the selector leaver assembly. They also stated these were coded to the car so a 'used but good' one from a breaker could not be used. Anyone know if that's correct?
I'm offshore at the moment so limited in what can be done but would be grateful for any advice if anyone's had a similar problem.
Thanks for reading.
Yes, the shifter is a likely source of your problem. And yes, the shifter has a security code which must be programmed to match the ECU and EIS. However the shifter's security code is in a small module which can easily be transferred to a replacement shifter. Of course you have to open the shifter assembly for that, and that is a good time to replace the troublesome/breakable plastic lever with a stronger metal one.
Too bad you already wasted time and money replacing your consumer battery. There is nothing special about that battery, any 12V battery that can supply even a modest amount of current would work fine. I suspect MB specifies an AGM battery knowing that these cars are likely to drain the battery and AGM are more likely to recover from over-drainage.
Hi mrvedit
Thanks for the response. I agree re changing the troublesome plastic lever that breaks when the shifter assembly is out of the car. So is the gearbox control module located within the shifter assembly along with the separate security code module? And is it the gearbox control module that controls the indicator lights in the dash display? Strange that it's intermittent but these cars seem to throw up all sorts of anomalies. The drivers seat access buttons on the top of the back rest haven't worked since I bought the car last July and started working again of their own accord last week. I love faults that fix themselves :-)
The consumer battery that was on the car wasn't brilliant so needed changing anyway so thought I might as well get the correct one. It tends to get left for long periods when I'm offshore if no-one uses it.
Hi All
I'm a little confused as to what is in the gearshift assembly as, from the pictures on eBay, there doesn't look to be much in the way of wiring. A previous thread also shows an 'ETC' Transmission Control Module located (on a LH drive car) on the RH side behind the panel in front of the door (where the bonnet release is on a RH drive car). Which part do you actually think is causing the problem (to confirm I have the 5 Speed Auto, not the 7G 7 speed)?
Thanks
Are we not all talking about the "shifter" for the automatic transmission as in the picture below where I am removing it?
There are two electrical modules. IIRC, the right side has the optic pickup (or microswitches) which indicates the position. The left side is the security module.
Thanks for that mrvedit, that's the bit I was confused about. Most of the items on eBay don't show the connectors. I know what I'm looking for now.
Thanks
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