Auto Repair: Windshield Washer Motor Replacement

I have no exciting tool restoration to post about today.  Just simple, money saving, diy car repair.  As I was driving to work the other day, I decided to clean off the windshield using the washer built into the car.  I rotated the control stalk to spray the windshield with fluid but there was no spray.  Of course the wipers moved and smeared what ever it was all over the windshield but that is beside the point.  The first thing one thinks, I suppose, is that it is simply out of fluid.  Due to the shape of the tank I can’t tell how much is in there.  I went ahead and topped it off but it still wasn’t working.  Hmm, what’s wrong.
The washer system is pretty simple.  You close a switch, rotating the control stalk in my truck, and voltage is supplied to a pump on the washer pump tank.  The pump pumps water up a hose that connects to the spray nozzles that shoot the fluid out.  As you can see, there’s not that much to go wrong with the system.  Still, we can take a systematic approach to the problem to solve it.
The first step was to refill the tank.  Obviously, the pump can’t move the washer fluid if it isn’t there.  If it still doesn’t work, the second step is to turn the washer on again and listen for the sound of the pump running.  If the pump is running, but no fluid is spraying then you probably have a break in the line from the pump or the pump is clogged.  Sure the nozzles could be clogged too, but the chance of both clogging completely without any previous signs (poor spray pattern) is pretty remote.  I didn’t hear the pump running which leads to two options: the pump is dead or not receiving voltage.

To test for voltage I needed to find the motor and disconnect the connector on it.  Logic dictates that the pump will be at the lowest part of the tank and once the air cleaner box was out of the way, sure enough, there it was.  You can see the pump and the disconnected connector in the picture below.  Note that there is a pink and black wire on the connector.  Black is pretty much always a ground meaning that the pink wire is the positive wire.

 

To test the voltage is pretty simple if you have a multimeter. I’ve found that small paper clips fit into connectors well without damaging them.  Once they’re inserted, and NOT touching each other, the multimeter leads can be hooked up to the paper clips.  Next, attempt to run the washer and see what voltage is present.

 

I used my Fluke 87 multimeter to test the voltage.  It turns out that the pump is pulsed by the wiper control module meaning that the voltage varies up to a max of battery (or alternator) voltage and down to zero.  Luckily, my Fluke has a max and min recording ability which allowed me to easily see the peak voltage.  It also allowed me to easily get this picture!  The truck isn’t running so the voltage seen is ok.  If it was running and I saw this voltage I’d be worried about my alternator.  Since I have the correct voltage, this leads me believe the problem is the pump.

 

What if you don’t have a multimeter?  Then you should get one.  Seriously, they’re pretty cheap especially at Harbor Freight.  Ok ok, if you don’t have one you can use a test light.  The factory service manual makes use of a test light to troubleshoot the washer system.  What is a test light?  It is nothing but a small light bulb connected to two leads.  As you can see below, one of the leads goes to a clip and the other goes to a pointed metal rod.  So, if you connect it between a voltage source and a ground it lights up.  Very simple and useful.

 

The manual has a flow chart that tells you how to hook up the test light to narrow down the problem.  You preform a step and the result leads you to another specified step.  The first step is to connect the test light to a ground and probe the pink wire while attempting to run the washer pump.  If the test light lights it means you’re getting voltage to the pump.  Next, it says to hook the test light to the black wire at the connector and probe the pink wire again while attempting to run the washer pump.  It lit again meaning I had a good ground and thus a good circuit.  At this point the manual instructed me to replace the washer pump.   Pictured below is the test light lit up in a successful test.

 

At this point the washer pump has been confirmed as being defective via two different, though similar, methods.  Time to replace it.  To remove the pump, I disconnected the line to the pump and  pulled the washer tank, which required removing one bolt.  Of course, once I had it out I found that I could have removed the pump without pulling the tank but I think it was easier with it out.  So, there’s the stock pump dated 1994.  The pump has a peg that pops into a recess in the tank and a bottom pickup that fits into a hole with a grommet in the tank.  Replacement is simple, remove the old pump and grommet, put the new grommet in, then put the new pump in.

 

Here’s the old pump (left) and the new pump (right).  They don’t match up perfectly but it turns out that you can rotate the bottom of the pump to align the output tube.  I had plenty of space either way.  If you look closely at the bottom left of the old pump, you’ll notice a few ants.  A colony of tiny ants had decided to take up residence at some point.  Odd.  Maybe they killed it.

 

So, there ya go, simple diagnosis and replacement.  At $15 for a new pump, it was pretty cheap too.  It took me longer to take the pictures and write this post than the actual diagnosis and replacement took.

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