Intermittent wipers not working

[LincolnLSPaul]

My intermittent wipers will only work for about 2-3 minutes after starting the car. Does anybody know which of the 3 relays control the intermittent speeds? My thought is the relay needs replacement.

[The_Mechanic_33]

year make and model?

[shorod]

Make and model are Lincoln LS, but year would help, and for most posts, please also include engine.

In this particular case, is it only the intermittent function that doesn't work? Does the low and high speed work? Does your car have the rain sensing feature?

-Rod

[LincolnLSPaul]

Sorry for the oversight. It is a 2002 LS with the V8. It also has the Rain Sensing feature. The Hi & Lo are working just fine. Per a previous post I checked the amber light on the Rain Sensing unit. It is working. The intermittent will work when I first start the car but after 2-3 minutes it will quit working. The fuse in the passenger kick panel is fine, as well. Thanks for helping.

[shorod]

So is it when you're set to the rain sensing mode that the wipers stop working, or is it the same if you use the manual intermittent mode? If you wiggle the stalk or change the setting do the wipers make a pass?

I've had to disassemble and clean the contacts in the wiper stalk before on other Fords to get the intermittent feature to work reliably.

This afternoon I'll try to take a look at the wiring diagrams and see if something jumps out.

-Rod

[LincolnLSPaul]

It happens in the manual intermittent mode. Additionally, the rain sensing does not appear to work when the intermittent stops. Unfortunately, it does not make a pass if I adjust the manual intermittent setting. It will only restart if I turn the car off and usually it has to sit at least a few minutes.

[shorod]

The wiring diagrams for this system are not as clear as I'm used to from Ford. From the diagrams though, it is evident that the relays are the same whether you are in the intermittent mode or the high/low modes. So I don't think you'll benefit by playing with any of the three relays. The relays are controlled by the Front Electronics Module (FEM) and the Rain Sensor Module does feed in to the FEM, as well as going straight through the clockspring to the Multifunction Switch.

Your symptoms sound more like a cold solder joint or connection that is going open circuit once it heats up. It would appear from the diagram and description that the likely culprit would either be the rain sensor module or the FEM. I'm not sure how to determine which is the culprit without tapping in to the trigger output from the rain sensor module to make sure the FEM will allow a pass. Also from the diagram, one input to the Rain sensor module and FEM is at the same resistance for "Off" or "Intermittent." That same line then is at the same potential for "High", "Low," and "Mist." The other line connected to both the rain sensor module and FEM is at the same potential for "Low" and "Mist" but at varying resistance/potential for "Off" and "Intermittent" and shorted to common for "High."

If you enjoy wiring diagrams, send me a Private Message requesting the diagrams and I'll send you PDF versions. I've looked at them about as much as I want to.

-Rod

[LincolnLSPaul]

Thank you for looking into it. I will send you a private message for the diagrams. I will post my findings when I get some results.