Electrical problem

[John S]

Hi there,

Had M170 jump started by a mechanic and as I can see he has applied too much voltage because the wipers started moving very fast when it was started and the radio amp went up in smoke! Now, the car will start but the glow plugs won't come on and also the handbrake light doesn't light up in the speedo area. What looms/relays/fuses might be at fault here?:banghead: I cannot prove that the mechanic was negligent and to be honest I'm just glad the car works and has working brakes at the moment!

Any help appreciated as always....

John

[tony]

sounds to me like he used 24volts to start it ,the bulb will have burn out and want replacing, as will the timer relay for the glow plugs.
if this is correct the mechanic was indeed negligent.

[H48HPE]

not really sure to be honest. Do the wipers still work? if not you could have blown one on the fusible links off the battery, two shown on the diagram, one has the starter solenoid circuit off it, so thats clearly still good, the other has amongst other things the wipers off it, so a check there will prove if thats still good.

other than that i can only suggest checking each fuse for damage and go from there.

I dont really like jump starting, seen it go wrong a couple of times in various forms so I would always avoid it where possible.

Andy

[Steve H]

Trouble with charging (and I suspect this has happened in your case) can be if you've got a nearly open circuit cell in the battery causing low capacity in the first place, then a fast charger will shoot the voltage sky high. The battery normally holds the voltage down, soaking up lots of current really fast.

This would easily explain why the wipers worked fast, probably blowing the fuse, and also the radio amp blowing. I'm not sure whether they both use the same fuse - it might easily have been blown by the radio going short circuit, taking out everything connected through that fuse.

Agreed with Tony, the bulb on the dashboard is probably blown. You only need 20% overvoltage to reduce a bulb's life from 1500 hours down to 20 minutes. Anything over 20% overload and the bulb blows immediately.:(

Steve H

[exminiman]

why did you get it jumped off in the first place? sounds like maybe the voltage regulator could be faulty... this is the roughly triangular pack bolted to the back of the alternator and regulates voltage to 14.7 volts....if it goes knack then the voltage will spike as engine speed increases symptoms are wipers gong faster heater going faster tapes playing faster and bulbs blowing left right and centre..... the jump machine may have blown it, but elctrically it is a consumable as it comes complete withthe brushes....costs about 12-16 quid and can be fitted in 20 min laying on yr back....good luck

[B18 GPC]

I started kkw on 24v :o

Im back to the forums.. sorry ;)