Alan Hawley Posted December 21, 2020 Report Share Posted December 21, 2020 I having problems with my wiper motor.When connected to the wiring but disconnected from the rack the motor runs for approx 25-30 seconds and then goes into start/stop.However if I switch on the heater fan the wiper seems to run for minutes.The motor even runs with the heater fan switched off. I have exchanged the motor but same symptoms.Do you think my voltage stabiliser is faulty or a defective heater fan switch or some other cause.My car is a4A with a two speed motor. Any thoughts appreciated Thanks Alan. Quote Link to post Share on other sites
RogerH Posted December 21, 2020 Report Share Posted December 21, 2020 Hi Alan, Run the motor isolated form the switches etc - ground the green/brown and green/red wires. Remove the blades or lift off the window. This should allow the motor to run freely. If it runs for 5/10 minutes then it would show that the motor is probably innocent. If it stalls sooner than planned then apply +12V to the Green wire to the motor. The voltage regulator has no function in the running of the motor other than the Green 12V wire is common to the VR input. If the motor doesn't run correctly in this free running mode then there is an issue with the motor. Have you checked the brushes etc.? Roger Quote Link to post Share on other sites
Alan Hawley Posted December 21, 2020 Author Report Share Posted December 21, 2020 Roger thanks for your response,The motor works on the bench but not on the car.The motor is the second I have tried.Why should the heater fan switch have an impact on the wiper motor working !!! Alan. Quote Link to post Share on other sites
RogerH Posted December 22, 2020 Report Share Posted December 22, 2020 (edited) Hi Alan, the fan switch in itself can't be the problem. However the current drawn by the fan motor may be doing something. The heater and wiper motor share a common connection on the 10V Voltage regulator If this connection is dodgy then the fan current plus the wiper current may make the connection hot and increase resistance. Clean all the contacts at this common connection. Run the fan with a +12V direct from the battery. see what happens. It runs OK then tidy up the VR wiring and /or replace the VR Look here to see the wiring http://www.advanceautowire.com/tr24a.pdf Roger Edited December 22, 2020 by RogerH Quote Link to post Share on other sites
peejay4A Posted December 22, 2020 Report Share Posted December 22, 2020 Did it ever work properly or is this a new problem? Quote Link to post Share on other sites
keith1948 Posted December 22, 2020 Report Share Posted December 22, 2020 Hello Alan Had a similar problem a while ago which turned out to be a loose connection for the fuse in the fuse holder. Suggest you start there, then check common connection on voltage regulator as Roger said. Then up behind the steering column there is a connection on the loom (look for green wires poking out) and then from there to motor. Check the black earth connections around the wiper motor. Then check the wires that go back to the dashboard switch which in turn earths via one of the black wires next to the motor. Make sure you have some water on the screen or remove wiper arms so resistance from wipers on screen is removed. Pretty sure it will be a dodgy connection. Good luck Keith Quote Link to post Share on other sites
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