Wipers only function on high

[RVPoppy]

2005 workhorse W20. Tiffin Allegro Open Road
Have had problems with multifunction switch since early on. The four way flashers would only work if switch was pushed slightly to the side. I made a workaround for that since all other functions worked reasonably well. Driving back from Texas in early January, the wipers would no longer work on intermittent or low, only on high, and would stop wherever they were when I turned the switch off.
I finally got time to order a new multifunction and installed it today. The hazard flasher problem is resolved and works perfectly. All other functions except the wipers are okay. The wipers still only operate on high and will not Park when I turn them off. Any help would be greatly appreciated!

[JCM]

I am having problem with my windshield washer- doesn't work or even make a noise. Suggestions?

[Full-Timers]

Check the connector that is on the outside of the firewall up near the brake booster. That is the one that goes to the wiper motor. If there is just a little bit of moisture or corrosion in it, it will do strange things. The connector is in a vertical position and water can get into the back side.

[Ultra RV Products]

Wiper control module has failed.


https://www.ultrarvproducts.com/W000...Control-Module

[yeloduster]

Good Morning,

Jon from UltraRV is probably correct but to be sure that you don't buy something that you don't need you should make some measurements.

There is bundle of wires that come to the wiper motor. For most of us the motor is has a plug that is connected to a wiring harness of the motorhome. Unplug that plug. It should have 5 pins. As Full-Timers suggested it may be full of moisture or rust. Carefully clean the plug then plug it back in. It might fix your problem...but probably not. You need that connection to be clean and tight in any case so cleaning it was not wasted.

Note: THERE IS NO STANDARD COLOR CODE FOR THE WIRES AT THE CONNECTOR. THERE IS NO STANDARD PIN NUMBERS.

Devise a way to number the pins in the connector and make a chart. There are only 5 pins so it isn't too complicated!

If things still don't work unplug the wiper motor again. Get your volt/ohm meter and set it to measure VOLTS. With the ignition OFF measure the voltage between a ground point on the chassis to each pin on the connect that goes to the wiring harness. All pins should measure 0 Volts.

Change your meter to measure Ohms. Again measure each pin. One pin should be very low resistance...probably the same as if you just connect your probes together. Label this pin on your chart as Ground.

Turn ignition to ACC and the wipers to OFF.

Set your meter to measure VOLTS. Again measure each pin. One of the pins should be 12V. If you find no pin with 12V or you find a pin with voltage that is much less than your battery voltage STOP...order a wiper control module (WCM)! If you find a pin with 12V then label that pin on your chart as PARK. This voltage is used by the WCM to drive the wipers to the appropriate parking spot on the windshield. Note: The park pin is always 12V when the ignition is on.

Next, turn wipers to HIGH. Again measure the pins. You should now find 2 pins with 12V. The park pin and another pin. Label the other pin on your chart as HIGH.

Now turn the wipers to LOW. You should now find the PARK pin high because it is always high and another pin with 12V. If you have no pin other than PARK with voltage...STOP...buy a new WCM from Jon! If another pin has voltage then label that pin on the chart as LOW.

At this point you have identified 4 of the 5 pins. Label the 5th pin SWITCH. SWITCH is always 0V.

Here is a sample chart (I have arbitrarily labeled the pins, you will have to assign your own pin numbers):

• 1. Ground

• 2. PARK

• 3. LOW

• 4. HIGH

• 5. SWITCH

If you have all the voltages mentioned above then your WCM may be OK and your motor may be bad. The wiper motor has a low speed and a high speed winding. Low speed winding is used for ALL function except HIGH speed. It is possible for the low speed winding to be bad and the high speed to be good.

If you order a new WCM UltrRv will suggest that you change FUSE #22 to a slow blow self resetting fuse. Do that.