CLK 270cdi No gauges or electrics on dash after jump start?

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alf1956

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Jul 1, 2011
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Car
clk270 55 plate diesel
Hello fellow members.
I have a 55 reg 270clk 270cdi which has been stood for couple of weeks & I went to start it last Thursday & it only just started, I went to it today & it turned over but very slowly then it died so we jumped it off a pick up whilst I put the jump leads on the pick up my friend connected the jump leads to the Merc but unbeknown to me he had connected the jump leads directly to the battery & not to the red positive terminal on the top of the strut & when the car started up I noticed that there were no temp/fuel gauges, no speedo, no rev counter in fact nothing on the dash was working. Could putting the jump leads directly onto the battery maybe caused an electrical problem?
 
Just jump starting could cause untold damage tbh.
Try getting the codes read but money is on a damaged SAM
 
Would I be correct in thinking that if you jump start the car with the leads on the red post on the suspension top & the earth strap on there that it does not cause any damage as I have jumped the car lots of times over the years using that method but never jumped started it directly onto the battery
 
I can’t think of any reason why connecting directly to the battery would do any damage on a clk.
happy to be proved wrong, and I’d be interested to find out what the actual fault is.
 
Jump starting is jump starting, does not matter where you connect the jump leads, either on the battery terminals or on the live terminal under the bonnet.
If you need to do it again, try putting the headlamps on as it takes some of the spikes out, that can cause damage.
At the moment, I would disconnect the battery for a while and then connect it back up and see if that has cured your gauges not working.
Then if not .... as WM has said, codes read and take it from there.

Steve.
 
Anything newer than a W202 can in theory cause catastrophic damage.
 
I can’t think of any reason why connecting directly to the battery would do any damage on a clk...

Jump starting is jump starting, does not matter where you connect the jump leads, either on the battery terminals or on the live terminal under the bonnet....
^^^^^^^^^^
As above.

Anything newer than a W202 can in theory cause catastrophic damage.

^^^^^^^^^^
This could be your issue. The proper way of jumpstarting a modern car is by removing the battery from the other vehicle and connecting it to your car in parallel as an external battery. This protects both your own car and the donor car. And yes me too I have jumpstarted cars directly when under duress and got away with it... but it's a statistical matter.

So yes, you may have damaged the electronics on the car, but equally your battery might be dead, or the terminal connections are cortoded or somehow became loose - you really need to check these as well. Start by testing the battery voltage between the charging point and the strut. You can also try trickle-charging the battery to see if it can be revived in this way, or replace it with a new battery altogether.
 
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I would still check all the fuses one by one before going to a specialist to have more detailed checks done.
A fuse often does it’s job in a situation like this, protecting the electronic items during a voltage surge or short circuit.
And get a new battery.
 
The battery is in good order & has charged up with just a little run & started ok this morning & is only 1 year old it only went flat due to the car been stood for a good few weeks without being started & run for any length of time.
 
Checked every fuse under the bonnet & in the boot & all good, took the battery off for approx. 10/15 minutes & re-connected but it was the same.
 
I am going to disconnect the battery today & put my c-tek charger on it for a few hours to see if that will do anything, I am really clutching at straws
 
I am going to disconnect the battery today & put my c-tek charger on it for a few hours to see if that will do anything, I am really clutching at straws

Clutching at straws not recommended, not very effective. You should try something else! Unfortunately no idea what.
 
So, bad news that a disconnect did not cure anything, at least it is a cheap option.
It is good that the battery charged up quickly when running the car and will now start it. Using your C-TEK will just top up the battery, it is a maintenance charger, If you need to charge a battery from flat ( below about 8 volts ) then you need an old type charger.
You say you have checked the fuses, was this just visual? Do you have a multimeter, have you tested that there is power going to every fuse that is relevant, a simple 12 volt tester with a point on it can be just as useful.
Is it just the dashboard and gauges that have gone? everything else on the car works? If so, you just need to identify the circuit that provides the power to the dashboard. You really need a wiring diagram of the front SAM unit or which ever one feeds power to the dashboard to do this properly. Ultimately, the front SAM will need coming out and checking for blown components or tracks.
If any oof this is beyond your diy capabilities, then get a good Auto electrician to have a look. You do not need to do any more damage. He will thank you for a bit of a wiring diagram though if you can find one. If you let us know where you live, then someone may know someone close to you

Steve.
 
Was the engine of the donor car running while connected to yours before or after it started?

My post 202 (203) car has been jump started and has also started other cars quite a few times, all without drama. The key to successful jumping as far as I'm concerned is no engines running during the start process, then disconnect the leads before starting the donor car.
 

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