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2000 Mountaineer Washer pump


August 8, 2015
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City, State
Crivitz, Wi.
Year, Model & Trim Level
2000 Mountaineer
Before anyone dismisses this as a typical "you forgot to check this" thread" I'm hoping it's that easy, but I don't know what I'm missing.
So my washer pump quit working just as we started getting snow of course. No big deal, check the fuse all OK, wipers front and rear work. Couple of bolts and two nuts and the washer/ coolant reservoir is out. No clogged screen, so pull the pump. Insert 12V test light to positive socket of pump harness and ground negative to battery. Push the squirter button and on comes the light so button is working. Changed leads so light is on negative side to prove I have a good ground. Yep all OK.
Purchased and installed new pump. Worked once and then quit.Still won't work. Checked fuse again and now it's blown. Replaced fuse and still no pump. Found a splice in the harness of both wires so it could still be a grounding issue. Cut wires and retest./ Each time the button is pushed my light comes on, but no pump. Pulled pump and direct tested with 12V from batter. Pump works fine.
I'm starting to think at 53 my brain is failing. How can something this simple be so frustrating. Is there something I'm missing. I don't see a relay of any sort that could be dropping my voltage enough to prevent the pump from working. I ran out of time to get my meter in there to be sure that I'm getting 12V, but the test light is nice and bright. I just nutted the wires back together so I could test easier until I figure it out. I'm also thinking of splicing in another ground to see if there is a ground somewhere else that's bad.

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When mine quite working one day, the problem was the connector to squirter motor, all I had to do is pull it (wire connector) off and on several times to make a good connection to get it to work.

Thanks for the reply. I'll look at that closer. I've had it on and off several times while trouble shooting. One thing I forgot to mention was that when I installed the new pump it worked one time and then quit and that was when I found the fuse blown. I added this to the original post.

Sooooo... I got the dang thing working, but it doesn't make any sense to me. I ended making some pins that would fit in the plug so I could check the actual voltage when the button was pushed. I only got like 2V. When I used an external ground I would get 12V so I was correct in believing that it was a grounding issue.
The confusing part is that when I spliced the two sections of the factory ground together and tied in the external ground it would drop back to 2V. I ended up disconnecting the harness side of the ground splice and just grounded to the chassis and to the plug and it works fine. My confusion is that it seems like there must be a 12V shorted to ground somewhere, that would cause the voltage to drop back to 2V when hooked to the harness ground. However when I check the voltage at the harness ground I don't show any voltage that may be coming from something else and I don't have any blown fuses or check engine lights on. Also, I had noticed that since this issue started my gas mileage has been very poor. I normally run in the 18mpg in the Fall and then when the temps drop below freezing I will drop to 15.5-16.5mpg. I have been consistently in the 13-13.5 mpg range since it cooled off. Any body have any ideas

You may have chaffed wires somewhere. I have seen chaffed wires on my 97' Explorer down to bare wire, fortunately it was against plastic and not metal.

Very odd situation
Seems like the multifunction switch is okay because with your homebrew (bypass) ground wire you get 12V
Its only when you include the factory ground that the voltage drops to 2v? and even when combined with the bypass ground?
I would need to look at the wiring charts to see what ground location the washer pump uses........ something in there has a short.

For your MPG drop, have you checked tire PSI? Alignment? Any brakes dragging?

Thanks for replies guys. Yep, if I use the factory ground wire even in conjunction with the factory ground I get 2V. It's going to be monumental trying to figure where a wire chaffed. The thing is a road queen except for the 13 miles of gravel going back to our camp.
As far as the mpg I was running my summer tires @ 42psi with a max of 44psi and getting the 13.3mpg. Then I switched to my Khumo AT51's for winter running @ 46psi with a max of 50psi. and the mpg stayed the same. The thing runs straight as an arrow with no pulling. I'll check the brakes closer tonight. I only get about 20 minutes of decent light after work this time of year. If anything I can only be accused of over maintaining my vehicles. There's only about 15K on the all new front brakes. Kind of makes me mad when I think about it. I've put 50K on the truck and when I first bought it, I bought top of the line everything for the thing. Brakes including rotors, pads, calipers, then bearings, hubs, axle seals, cv's, shocks, ball joints, tie rods etc. at all 4 corners and I still have had to replace one hub assembly and the front brakes and like I said she is pretty much a road queen since she's my DD. I sure lover though.

Well your bad mileage could be based on the factory your not running the right tire pressure. 30psi is the correct pressure on our vehicles. Also have you had a tune up done recently? Plugs? Wires? Fuel Filter? All fluids maintained? Cleaned the maf and throttle body? Is it AWD? Got remember that'll hurt your mileage as well. Any other issues that need addressing? I know these vehicles can be a pain because they are older. Trust me I understand Im currently in process of replacing my oil pan gasket. On a AWD that is a venture in of itself.

morbid, thanks for the reply. Keep in mind that the psi rating you give is for the stock tires that originally came on the vehicle. Once you replace the tires you have to go by that tires manufacturer psi settings. My summer tires which are generic wranglers have a max psi of 44psi. I run at 40-42psi on those and my winter tires are Khumo AT51's with a max pressure of 50psi that I run 44-46psi. A harder tire typically increases mileage due to decreased rolling resistance.
When I say my mileage has dropped it is based on the same tire combinations and pressure settings. I've had the truck for 5 years and it is AWD, but again, I'm basing my observations on my exact experience with this truck, not what I think I should be getting, but on what I have actually gotten based on miles driven and gallons of fuel used. I don't put much stock in the factory display of mpg.
I actually have a can of MAF sensor cleaner in the truck and I was going to go for the air filter after that. I have about 30k on the filter and plugs so they are probably due. I am also looking at the plug wires since they have about 50K on them.
That said since I eliminated that factory ground on the washer pump my mileage has come up to 15mpg even with 10 minute warm up times in the mornings since the temps have dropped into the teens.
I'll keep you guys posted.

oil pan gasket in the truck is a PITA but it can be done.
Here's a hint: cut the new gasket.
Makes it much easier to get in the pan and around the pickup.
Cut the gasket at one of the back corners... then use silicon to glue it back together.
This way you do not have to drop the pan completely out and can fish the gasket in place

I understand about not having any sunlight after work!
I live in North Idaho......waaaay north sun is down at 4:00 pm at my house this time of year

Tire PSI has alot to do with MPG on these trucks, I adjust my tires based on where I am going, long trips on highway, run the max PSI (48-50)
Snow or slush on roads, take them down to 38 or so
Gravel road all summer, 32 psi is nice and soft ride.......
It maybe time for a fuel filter, air filter, clean the mas air flow sensor and of course check condition of spark plugs and wires. I have heard the 02 sensors get "slow" after 150K miles or so and new ones can help bring back some MPG...only the two main 02 sensors need to be changed, not the catalyst monitors....

Top of the line parts are not always so top of the line, sometimes you are paying for the same cheap part just in a nicer box
I had some trouble with even the good parts! You can get front wheel bearings for these trucks for $40 each or less! You get what you pay for. Over the years I have learned to stick with Ford, Spicer, Timken, Bosch and the like it saves money in the long run

410 I feel you man! After doing my own brakes for the last 35 years I thought I had found a good combo. I typical use as good of a rotor as I can and the use semi metallic pads. For me, I have found that no matter the claims there are no rotors that will withstand the heat that the ceramic pads create. As far as the pretty box syndrome I can't agree more.
I do tend to run my tires a little higher than you even on the gravel, because up here gravel is anything from 3/4" crushed to 2" breaker run which is like running on broken beer bottles. With the side wall flexing at lower psi flat tires due to punctured sidewalls is way too common.
I'm up at camp in the UP trying to fill one of my buck tags during the black powder season and the temps down home are supposed to get up around freezing this coming week so I'll be hammering out some of the obvious stuff. Meanwhile up here we have a foot of snow on the ground, temps will hit about 3F tonight, and I have a couple 12'ers of creamy dark for snacks so I'll just lay out my plans for the week while I enjoy the absolute solitude. From what I can tell there is only one other guy up here about a mile away and he's a good buddy of mine. Otherwise it's about 13 miles as the crow flies to the next human being. Man I Love this place!