rusheadcarerra

I have an 89 F150 4x4. We just bought it and it is a great truck. Problem is the wipers. The first position of the **** style switch on the dash going clockwise (this is not one of those column-mounted multi-function switches) appears to be a delay-type position as it feels like you're turning a potentiometer. The next three positions going clockwise are switches, that is, they click in. Only the most clockwise position to the right works the wipers so I only have one wiper speed working. None of the other positions work. I replaced the dash switch with a switch from an 89 F150 parts truck we have, but it's the same symptom. Now it's possible that these switches can go with time and the one from the parts truck was just bad too. But I was wondering if there is a wiper control board/module between the wiper switch and the wiper motor. The Haynes manual appears to show one. The motor looks like it has a flat section coming off of it with a connector wired to it, and then the motor itself also has a connector attached. Is there anyone who has had this problem that can tell me what to replace?

aliens8mycow

There is also a regulator between the switch and the motor. I think the regulator is mounted behind the same panel that the switch is on.

The far left 'adjustable' area is for delay wipers. The first click going clockwise is off (where the switch should normally be). Next two clicks going clockwise are low speed and high speed. You'd normally have the switch in the center 'off' position, and turn it left for delay wipers or right for low/high speed constant wipers.

Do the wipers work on delay? I'd try a new regulator (especially if you have one in a parts truck)

Just call me Sean

iTrader: (1)

My truck does the exact same thing. At first it was worse, they wouldn't park and they stopped intermittently. I changed the wiper motor and then they would park but still no low speed or delay (even though I think it doesn't have delay). They still stop intermittently. I wasn't sure what I was going to replace next, the switch or the interval governor, but since you say the switch didn't fix it then I'm going to replace the interval governor now.

rusheadcarerra

Yeah I am sort of at a loss now because yesterday I tried the wipers on my spare truck and they are doing the exact same thing. Now I admit I have introduced a variable by using the main truck's dash switch on the spare truck. It's possible that the governor/regulator is bad on both vehicles, since apparently Sean has the same problem. I'd bet that it is a common failure. Perhaps it is designed such that if the regulator fails, the system still defaults to one wiper speed all the way to the right. If that is the case, then the third switch position effectively is wired straight through to the motor, bypassing the regulator all together so to speak. I am going to check the function of the switch with a meter and then trace the wiring to where the switch goes. I would guess the wiper motor is OK and the regulator is gone bad. I'll post the results as soon as I fix the problem!

aliens8mycow

Good logic - like the fan control on your HVAC panel, the blower motor is ready to go full blast. The resistor tames it down to give you 3 lower speeds. If that resistor fails, you have off and full blast.

Same logic should hold true on the wiper governor. The switch itself should outlast just about everything else in the system (unless you wreck the truck and your knee plows through the switch).

Just call me Sean

iTrader: (1)

You are correct, the high speed wire bypasses the interval governor and goes straight to the wiper motor.

rusheadcarerra

I just fixed the wiper problem!! It was pretty easy. The only tools you'll need are a quarter inch nut driver and a soldering iron. Disconnect the big red connector from the back of the wiper switch. The interval governor is a little black plastic box just to the left of the fuse box (behind the headlight and wiper switches). There is one bracket on the bottom rear of the module box and a single screw attaches it to the dash. Remove the screw and pull the module forward out of the dash compartment. Disconnect the black cable connector at the module. It looks almost identical to thee red connector at the wiper switch. Take the module assembly to a suitable work bench with plenty of light. Two screws hold the cover on. One of the screws also holds down the short cable assembly coming out of the box. Remove the two screws and carefully lift the PC board assembly out of the plastic box. Inspect the backside of the PC board. At one corner of the board is a large plastic relay and next to it is a heatsink with a special power resistor connected to the bottom of it. On my PC board, solder connections were broken on the heatsink and resistor leg. Carefully inspect all the other connections on the board for cracks. These are cheap, single-sided PC boards and the solder connections can break very easily, because there is no plating through the holes that the components go through. if you have an eye loupe or a magnifying glass, use them to carefully inspect all the connections. If any connections are broken, simply take some regular 60/40 electronic solder wire (the kind with a flux core) and solder any of the faulty solder connections. Of course, I also inspected the top (component) side of the board to make sure there were no burned components. On my board, the components looked fine. When finished, put the board back in the box and re-install. I did this and voilą! The delay works perfectly, and so do low and high speed wipers. I guarantee this is a common problem with these wiper modules. With those cheap solder connections, and the board rattling around in the dashboard for 20 years, this is the kind of thing that usually goes wrong. Hope this helps everyone. It was really pretty simple.

aliens8mycow

Well done! I'd have to agree that it's probably a lot more common than people think.

rusheadcarerra

Thanks Aliens! You certainly pointed me in the right direction.

Just call me Sean

iTrader: (1)

Cool, I'm glad you reported back with your findings. I'll try this in a few days and see if it works for me.