troubleshooting windshield washer pump

Discussion in 'Chevy Tahoe Forum (GMC Yukon, Cadillac Escalade)' started by heftylefty58, Nov 30, 2007.

  1. heftylefty58

    heftylefty58 Member

    I bought a used 2003 Yukon w/ 50k miles on it, and just realized that the front washer pump doesn't work--it doesn't even make any noise when I try to trigger it. (The wipers work fine, and the rear washer pump/wipers work fine, too.)

    I'm not terribly experienced with working on cars, but I figured I could at least check the easiest thing first: The fuse box.

    According to the owners manual, the fuses for the pump relay and the pump are located at the underhood fuse block. I confirmed that the actual fuse for the pump is fine.

    However, I'm not familiar with the fuse for the pump relay. It's much bigger than any fuse I've seen before, and I'm hesitant to yank it out because it looks like it is locked in there pretty good. Is there a tool I should use for pulling this sucker out, or is it not meant to be pulled off the block? In the diagram, this particular fuse has the numbers 86, 30, 87, and 65 on each corner. Any idea what these numbers mean?

    Any other troubleshooting tips you can offer before I just buy a new washer pump and try to replace it myself?

    Thanks in advance! :great:
  2. 84fiero123

    84fiero123 Epic Member 5+ Years 1000 Posts Platinum Contributor

    You can use a jumper wire from the battery to the pump after unplugging the wiring harness from it to see if it is working and a wiring problem or fuse.
  3. Sooner

    Sooner Rockstar

    I'm pretty sure what you're calling the pump relay fuse is the pump relay. I think the easiest way to troubleshoot your problem is to disconnect the wiring harness from the pump and have someone hit the washer switch while you check for power at the connector using a $2 test light. If you have power, it's most likely your pump. If you don't have power, I'd start with the relay. You can verify the pump by running the jumper wire from the battery. The relay can be tested too. But, it's a little more indepth.
  4. heftylefty58

    heftylefty58 Member

    Thanks all! I don't have a jumper wire or a test light, but I do have a basic $20 multimeter.

    At this point, I have another set of lamebrain questions since this will be the first time dealing with automobile electronics in my profoundly non-eventful life:

    For Sooner's test (where someone hits the washer switch while I check for power at the connector), I want to use my multimeter instead of the test light. Assuming my multimeter looks like the attached drawing, where should I set the dial? Also, what value(s) should I hope for in the reading when the switch is on vs off?

    I'm embarrassed to admit that I don't even know if I should be testing for voltage, current, or resistance. However, if this is any consolation, I do know this much:

    • Volts = Current * Resistance
    • Power = Volts * Amps
    • My read multimeter lead must be plugged into different holes depending on whether I want to test for current, voltage, or resistance. The black lead always goes into the COM hole.

    That pretty much sums up the extent of my electrical knowledge...despite 16 years of schooling.

    Please advise?

    P.S. Also, if I wanted to do Fiero's test (ie, connect a jumper wire from the battery directly to the pump), wouldn't I actually need 2 wires (ie, one for the positive and one for the ground) to do this test? Where exactly are the connections made?

    Attached Files:

    Last edited: Dec 1, 2007
  5. TahoeFever

    TahoeFever Epic Member 5+ Years 500 Posts

    take two leads black goes to comm and red goes to the other port on the meter set the meter to volts dc if thats an option since some meters give you the option of ac and DC in the car the most you would need is 12 volts DC unplug the connector on the pump it kinda clips off then you will two holes stick a lead in each hole worst it will do to the meter if the connectors are backwards will make the needle jump the wrong way. while connected get someone to activate the switch in the truck then see if anything moves on the meter.

    when you have a chance go to your local automotive shop and pick up a light testor since it will almost become the most used tool you can have for troubleshootiing.

    good luck :)
  6. 84fiero123

    84fiero123 Epic Member 5+ Years 1000 Posts Platinum Contributor

    Basic test light I have made in junk yards when I didn’t bring one with me to check things out before pulling them. Is a peanut bulb, spread the 2 wires on the plug out away from the bulb and there you go. One test light that is great for testing plugs like the one you are unplugging from the washer motor.

    Funny the meter you have looks just like the one I have in the desk right here for checking batteries in toys and remotes in the house.

    Turn the meter to the right and it has a V with a squiggly line over it and to numbers, 500 and 200, that is AC.

    Turn the meter to the left and that is DC, it has 500, 200, 20, 2000m, and 200m. Looking at your picture and my meter it looks like you have it in just the right place to test for 12 volt DC. You need to have the meter set for more voltage than you intend on testing to prevent burning up the meter. So 20 should be what you set it to.

    The rest, as far as plugs into the meter TahoeFever said right.
  7. heftylefty58

    heftylefty58 Member

    Sorry fellas--I didn't see your responses until after I worked on the car and then called it a day.

    Here's what I did, as well as my findings:

    1) Tested the pump connector's voltage while the wife triggered the pump. Result: Zero volts.

    2) Tested the pump's voltage at the fuse box while the wife triggered the pump. Result: Zero volts.

    3) Tested the radio's voltage at the fuse box. Result: ~12 V. (Dammit!)

    I was hoping that my multimeter wasn't working properly, or that I was misinterpreting the results. So, I proceeded with the following tasks:

    4) Removed battery.

    5) Siphoned out washer fluid tank; then uninstalled it.

    6) Bought new replacement pump from local auto parts store; then replaced the pump.

    7) Put everything back together. Result: The pump still don't pump. (Dammit!) The wiper blades still work, so at least I didn't worsen the situation.

    Apparently, steps 4-7 were a waste of time and money.

    Based on my results from steps 1-3, what would you say the problem could be, and what should I do from here? Should I replace the connector? Do I have to visually inspect the entire wire circuit between the battery and the connector? If so, how do I do this considering everything's so friggin crowded in there?

    Thanks again for your help.
  8. 84fiero123

    84fiero123 Epic Member 5+ Years 1000 Posts Platinum Contributor

    Blown fuse,
    Bad switch,
    Broken wire,

    Could be any of those, now that you have your pump out try testing that with a battery, I bet the old pump is good.

    As far as the rest, my bet is on a fuse. There is another fuse box under the hood. Did you check those?

    I’m not real familiar with the newer stuff so I really can’t say much more, I’m sure someone else here is. Wait before doing to much more.
  9. heftylefty58

    heftylefty58 Member

    Please delete this particular post. (My question in this post is now irrelevant because I found out that "w/s washer" exclusively refers to the FRONT washer. It does NOT include the REAR washer.)
    Last edited: Dec 4, 2007
  10. heftylefty58

    heftylefty58 Member

    I just bought a GM service manual (as well as a test lamp), and I can't believe I attempted to troubleshoot my problem without it. It's shocking to see how grossly I oversimplified things--the schematics and other diagrams are very helpful.

    The manual instructs to perform this test:

    Does anyone have any tips on how to do this?

    Do I need to buy special long-a$$ multimeter leads so that I can stick one of lead somewhere on the turn signal lever (where the wiper switch is), and the other multimeter lead on the windshield wiper motor (which is at the bottom of the windshield)?

    Also, has anyone removed/installed the windshield wiper motor? Seems like a pain in the buttocks--do I really need a battery terminal puller to remove the wiper arm from the drive shaft? Were you able to separate the wiper motor from the transmission assembly without buying these special tools:
    -J 39232 Wiper Transmission Separator
    -J 39529 Wiper Transmission Installer

    If I have to buy those tools for this job, I'm wondering if it'd be more cost-effective to simply have my local mechanic (or the dealership) try to fix the problem.

    What do you guys think?

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