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Matt
Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 22160
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a late 2003 CL55 AMG. It is stuck in park. There is

Customer Question

I have a late 2003 CL55 AMG. It is stuck in park. There is also some kind of electrical fault as it drains the battery, a brand new one, overnight.
Submitted: 3 years ago.
Category: Mercedes
Expert:  Shantal-Mod replied 3 years ago.
Hello,

I'm Shantal and I'm a moderator for this topic.

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Customer: replied 3 years ago.
Yes please I would like to continue
Expert:  Matt replied 3 years ago.

Hello

I'd 1st investigate the connections to the brake pedal switch and the wiring to it for any crimp damage or fraying. Ideally use a multimeter to check that the switch is working OK. This is because the gearbox controller won't allow the lever to shift from park until it sees that your foot is on the brakes

There should be 2 switches one for the brake lights and the other for the gearbox and both are located at the top of the brake pedal in the drivers footwell.

If this is OK then check the selector lever linkage for any broken parts and or missing bolts or if a bolt is partially out and is jamming things up

 

as for the current drain I'd first check the easy things like is the boot light or any other interior light staying on then check that the main battery connections are tight and in good condition also check the earth strap to the engine / gearbox.

Next I'd check the current drain aspect, the best way to find what circuit is causing the excessive currant drain is to fit a current sensing multimeter in series with the positive battery lead on the car and the battery, or use a current clamp meter on the battery positive cable.

A typical current drain with everything off and un-alarmed should be around 0.05Amp and if its higher than this remove a fuse and re-measure, if measurement doesn't change then replace the fuse and remove the next.

Once you've isolated the circuit with the excessive drain check the wiring connections and plugs to components and the wiring harness that runs by the engine bay fuse box - the wiring harness chaffs / rubs through and gets damaged - but its not always easy to see so be careful when checking..

Also check that the alternator is actually charging the battery in the car by taking a battery voltage reading with the engine off then another with the engine running. The 2nd reading should be higher than the 1st and climbing steadily. And also check that the alternator is secure to the engine as this provides the ground for the charging circuit and make sure that the engine / gearbox earth strap is secure and the contacts are clean and bright.


if the alternator appears not to be working - take it to a electrical specialist and ask them to test it as sometimes you can replace just the diode pack and this will repair the alternator without requiring replacement


And one last thing is – how old is the battery? – As even good quality ones need replacing every 5 years and faulty battery just won’t hold a charge


Customer: replied 3 years ago.
Hi Matt, thank you, I will translate your reply in Italian to give to the frustrated Italian mechanic! I also can hear a single click from the gear box when I put my foot on the break pedal .
Many thanks
Beverley
Expert:  Matt replied 3 years ago.
Understood Beverly

let me know how you get on,
just reply on this post
Customer: replied 3 years ago.
Hi Matt, found the two boxes near the brake pedal, looks as though I need a 02W20 part ! Can you send me one from the UK or should I just go on line an order one?
Many Thanks
Beverley x
Expert:  Matt replied 3 years ago.
Hello Beverley

It would best to order 1 online as I'm not setup to take parts orders