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- Nov 3, 2014
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The front wipers on my 2009 Ducato based Motorhome would sometimes not start for several seconds, all modes affected. Once going they worked and parked normally. After a few weeks the seconds of waiting had worsened into heart-stopping minutes. Rather dangerous when you have to pull over and wait till they decide to start !
Tests with a voltmeter showed +12 volts and ground were ok at the motor, and that the body computer was sending the right signals to the motor but it wasn't responding. Incidentally, the high and low speed relays are inside the motor casing, so two low current control signals (12V = OFF, 0V = ON) are sent from the body computer. There is also a signal going back to tell the computer if the wipers are parked. I could hear the relays faintly click. By chance the motor was playing up at the time of testing, and an experimental tap on its casing with a screwdriver made it start to work! I was then confident the motor was at fault. Just as well, as a body computer is £££s and needs coding.
I sourced a new Magneti Marelli motor from Euro Car Parts for £107 (Main dealer price £187). To swap the motor you need to remove the wiper mechanism. Firstly take off the wiper arms from the spindles, these may well be tightly corroded on - I used a 2 legged puller. Two of the three bolt heads for the mechanism are hidden below the plastic gutter at the base of the windscreen on the driver's side, so this too has to come off. It's held by 3 visible self tappers, plus 5 hidden plastic mushroom clips behind. I broke 2 of these when easing it off, and had to get new ones from the main dealer at £2 each (crazy - must cost 2p each to make). I couldn't get the gutter off without removing the bonnet ( 2 bolts on each hinge) which made access a whole lot easier. Mark round the brackets before unscrewing so you don't lose the bonnet alignment. With the motor half out its easier to release the 5 pin connector, which has a latch at the top that needs lifting - very hard to see in-situ. Whilst the mechanism was out I took out the arm spindles (one circlip each) and greased them. Or you could pay a bit more and get a combined motor and mechanism assembly.
When putting things back I used some silicone spray on the plastic clips to help ease them in, and some black RTV sealer along the top inside edge of the gutter to stop water from the windscreen leaking behind. I also sealed the feeble centre overlap joint to the other half of the gutter, to stop water leaking down onto the engine. Make sure you transfer over the pathetic piece of foam plastic that is supposed to keep water off the motor.
It might be feasible to swap the motor in-situ, but access to the 4 fixing screws is very tight so I didn't attempt this method.
I now have working wipers - very pleasing.
I couldn't resist taking the cylindrical cover off the old motor. The 3 brushes looked fine, but I suspect the bimetallic thermal/overload trip device on the PCB had developed a dodgy internal contact which would have open-circuited the earth return from the motor, stopping both high and low speeds.
Motorhomes seem to have more than their fair share of electrical gremlins, probably because they sit around unused in winter and the damp gets in without being regularly warmed up to dry it out.
Tests with a voltmeter showed +12 volts and ground were ok at the motor, and that the body computer was sending the right signals to the motor but it wasn't responding. Incidentally, the high and low speed relays are inside the motor casing, so two low current control signals (12V = OFF, 0V = ON) are sent from the body computer. There is also a signal going back to tell the computer if the wipers are parked. I could hear the relays faintly click. By chance the motor was playing up at the time of testing, and an experimental tap on its casing with a screwdriver made it start to work! I was then confident the motor was at fault. Just as well, as a body computer is £££s and needs coding.
I sourced a new Magneti Marelli motor from Euro Car Parts for £107 (Main dealer price £187). To swap the motor you need to remove the wiper mechanism. Firstly take off the wiper arms from the spindles, these may well be tightly corroded on - I used a 2 legged puller. Two of the three bolt heads for the mechanism are hidden below the plastic gutter at the base of the windscreen on the driver's side, so this too has to come off. It's held by 3 visible self tappers, plus 5 hidden plastic mushroom clips behind. I broke 2 of these when easing it off, and had to get new ones from the main dealer at £2 each (crazy - must cost 2p each to make). I couldn't get the gutter off without removing the bonnet ( 2 bolts on each hinge) which made access a whole lot easier. Mark round the brackets before unscrewing so you don't lose the bonnet alignment. With the motor half out its easier to release the 5 pin connector, which has a latch at the top that needs lifting - very hard to see in-situ. Whilst the mechanism was out I took out the arm spindles (one circlip each) and greased them. Or you could pay a bit more and get a combined motor and mechanism assembly.
When putting things back I used some silicone spray on the plastic clips to help ease them in, and some black RTV sealer along the top inside edge of the gutter to stop water from the windscreen leaking behind. I also sealed the feeble centre overlap joint to the other half of the gutter, to stop water leaking down onto the engine. Make sure you transfer over the pathetic piece of foam plastic that is supposed to keep water off the motor.
It might be feasible to swap the motor in-situ, but access to the 4 fixing screws is very tight so I didn't attempt this method.
I now have working wipers - very pleasing.
I couldn't resist taking the cylindrical cover off the old motor. The 3 brushes looked fine, but I suspect the bimetallic thermal/overload trip device on the PCB had developed a dodgy internal contact which would have open-circuited the earth return from the motor, stopping both high and low speeds.
Motorhomes seem to have more than their fair share of electrical gremlins, probably because they sit around unused in winter and the damp gets in without being regularly warmed up to dry it out.
. Yesterday we left for our 6 month trip and after using the wipers and a short stop, they stopped responding entirely and the issue is exactly as you described above (got 12V at the connector, hear the relay clicking...). We now parked at family and I found a new motor on Amazon with Prime delivery expected tomorrow.