I put new wiper inserts on my truck today, only to find that the wipers are acting up. Turn the switch and the wipers will work fine for a minute or two, but then they start hesitating and ultimately stop, usually mid-windshield. The wipers will then sporadically work in short intervals. All the wiring appears to be intact, and I ohmed out the wires from the connectors to the governor PCB, with acceptable readings.

The relay in the governor box clicks when the wipers stop working and then again when they start back up. Occasionally, when they hang up, the relay goes crazy, opening and closing rapidly.

My working knowledge of intermittent wiper circuitry limited, I'm looking for advice as to what to check and/or test.

Appreciate it.

 

The two most common failure mechanisms for the windshield wipers (intermittent or not) are the wiper switch, and the park switch inside the motor. When you shut the wipers OFF, you're not actually cutting power to the motor - you're diverting power back to the LOW input through a switch in the motor that stays closed until the wipers are in the park position.

You can check the switch by ohming out the appropriate terminals of the switch against the four different positions. Separately, you can check the motor itself by applying power directly to it. Applying power to the WHITE with ORANGE stripe wire should make the motor operate in LOW. Applying power to the BLUE wire should make the motor operate in HIGH. Do not apply power to the BLACK with WHITE stripe wire. The RED and BLACK with WHITE stripe wires should have continuity when the wipers are extended; there should be no continuity when the wipers are parked. In case it wasn't obvious, you would want to check the motor as I have described with it completely disconnected from the governor.

If both of those check out, suspect the governor. The governor is simply an electronic one-shot timer. Sorry, I don't know of a troubleshooting method because I've never taken one apart. If it's suspect, I'd simply replace it. The relay chatter could be a bad governor, or bad switch that's cutting power to the governor. A bad switch should be easy to spot based on the continuity test. See if the switch loses continuity if the selector **** is just barely moved out of position. The switch on my truck is very worn out - just touching it is enough to cut power to the motor and halt the wipers wherever they happen to be.

Reference the following wiring diagram: http://fordification.net/tech/images...aster_9of9.jpg

 

To follow up on what fmc is saying, I have almost the same problem as you (mine just stops) but I believe it to be the switch because of the simplest test (I'm not as sophisticated as fmc)....JIGGLE that SOB.
Does it change behavior? Mine did, it started right back up. Switch, right? I know, brilliant.
I bought an entire new harness to replace mine because I wanted to get inside my older one, fix it and see whats in that magic little box.

 

Perfect! Exactly what i was looking for, fmc. I'll test everything out tomorrow to see what's up. The governor is simple enough. Replacing a component or two would be pretty easy.

 

Bypassed the switch and the wipers worked fine. Holding the switch with the ground unhooked and the wipers on high, I'd feel the occasional pulse of electricity. Guess the switch has shorted out and is making the governor relay act up.

 

I'm not sure I understand your explanation. When you say you bypassed the switch, does that mean you bypassed the governor as well, and drove the motor directly?

What do you mean you held the switch with the ground unhooked? What does it mean that you feel an occasional pulse of electricity - as in you're getting shocked? Those results aren't really useful. The governor gets its ground through the switch. Any results you see with that piece missing are invalid.

These aren't really quantitative results. If you want to diagnose the switch, ohm it out with a multimeter. Use the diagram I posted to understand what poles of the switch get connected based on the position of the selector ****. Saying the switch has "shorted out" is ambiguous - shorting is what a switch is supposed to do. A switch is considered to have failed if it does not provide continuity between the necessary poles under each position of the selector ****.

 

Everything ohmed out alright.

I applied power directly to the white/orange and blue wires like you advised. The motor worked without a problem. I then plugged the switch in and turned it to high. I'm seeing 11.8 volts in and out of the switch. The governor appears to be bypassed for high and low settings. I'm also seeing voltage on the body of the switch. It appears as though the switch is shorting from the high/low circuit to ground.

 

However it is possible to have good test and have a mechanical problem in the switch that may not be detected by the meter.
For instance my switch works perfectly fine, sometimes. Then when it stops, I reach over and give it a little jiggle and it starts working again.
Not saying that's what it is, but those switches have gone through a lot of abuse in 40 years.
My '61 just had a broken wire just under the surface of the plug at the back with intermittent results.
Fun ain't it

 

I've fixed two trucks by reflowing the solder joints on the governor board. On my truck the wipers would wipe if I hit a bump but intermittent wouldn't work. A friend had a 76 f150 that lost all speeds but high. Both trucks had cracked solder joints on the circuit board. Look for a thin black line around the components lead where it sticks through.

High speed bypasses the governor but low speed passes through it.

 

I, too, had this issue. One day, the ww stayed on continuously. Found that the wiper switch itself had destructed on the back side. One for thought.