Valeo Service has received a number of wiper motors returned under warranty, with a fault stated as intermittent operation or not working. After analysis of the returned parts where no fault has been found, further investigation has revealed an issue with the vehicle’s wiring.
As a vehicle gets older the wiring becomes brittle and the insulation hardens. When the wiring passes through different sections of the body (bodyshell to boot or door for example) the wiring is flexed and bent.
On a vehicle where the wiring has become brittle, this flexing will cause a break in the circuit and will show a non-operation of the unit it is supplying power to, causing an incorrect diagnosis of a failed part.
If the plastic covering has hardened through age, the wire will no longer be sufficiently insulated and will come into contact, and short circuit, with either a metal section of the vehicle’s body or contact another exposed wire in the area.
This will produce either an intermittent fault with the part, the part will not work or an erratic fault with an adjacent part (for example, the boot central locking not working but rear wiper motor working – even when the switch has not been operated).
Wiring has become brittle due to flexing in boot apeture
If a part is misdiagnosed as faulty and a replacement is fitted, the issue will still be evident so this will result in lost time and money from replacing a non-faulty part.
When replacing an electronic part that is showing signs of a non-mechanical fault, the wiring feed must be checked first to ensure power is not interrupted by another issue on the vehicle.
This issue can also affect window regulators, central locking systems or any electrical part where the wiring is supplied through an opening body section.