Windshield Washer System - Diagnostic/Repair (2004 Thunderbird)

[JRMedved]

Thought I should share in the event others experience this issue...

I replaced the windshield washer pump in my 2004 Thunderbird last fall. After replacement, I noted that the hoses were relatively deteriorated and the nozzles on the cowl were plugged. I replaced the hoses and nozzles with new parts and all was working fine - for about a month or so.

Then I noted that there was a intermittent failure of the washer fluid spray. The wipers swept as designed when the wash function was enabled, but sometimes it would spray, sometimes it would not...no rhyme or reason. Since the wiper functionality worked fine in every other aspect (which ruled-out a fuse problem), I suspected perhaps it might be the result of a loose connection (at the pump motor). Since I'm pretty much homebound with nothing better to do (thanks, COVID-19!), I thought I would investigate and resolve this 'simple' issue.

Upon inspecting the washer pump connection it appeared to be tight. I checked the power feed circuit with a test light and got no light/voltage when activating the washer pump at the turn signal stalk on the multi-function switch (MFS). One thing that was unusual is that, according to the 2004 Ford Thunderbird Workshop Manual, this power circuit (circuit 30S-KA7) is supposed to be a RED wire with a white stripe (RED/white), but I noted that the connector had a YELLOW/violet wire. Circuit 31-KA7 (pump motor ground) is a black wire.

Concerned that I may have an open circuit, I checked both circuits from the washer pump motor to the wiper motor control module 12-PIN connector/Wiper Motor Jumper Harness (connector C110-9), which is located between the degas (radiator overflow) bottle and the power brake booster, and measured < 5Ω resistance both the power and ground circuit. So that ruled-out an open circuit (broken wire/loose connection) between the washer pump motor and the wiper motor control module.

Next, I removed the cover from the steering column to access the MFS. I checked for voltage between pins 2 and 5 (BLACK/red wire and the WHITE/violet wire) when the wash switch is activated. I noted 11.9-volts (good test). So, that ruled-out a problem with the MFS.

For all intents and purposes, there should be voltage to the washer pump when the switch is activated as no open circuits or switch failures are present. Further research indicated that the wiper motor control module has an integrated washer pump motor relay. Diagnostics indicate a failed internal washer pump motor relay in the module. This is UNUSUAL as this is the most unlikely failure of the system.

I've ordered a new motor assembly (Ford supercede part # 6L1Z-17508-AARM; Motorcraft part # WN778RM). I'll update this posting once I have received and installed the new motor assembly.

NOTE: If you have a 2002 model year car, the wiper motor assembly has a 5-pin connector at the wiper motor control module (instead of a 12-pin connector), and therefore would call for a different part number. That said, I am not sure if the wire color-codes, connectors, or pin numbers described in this posting are applicable to that model year's wiper circuits.​

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[Wolfe]

That is quite impressive troubleshooting. You are the man!!!! Wolfe Andrews

 

[JRMedved]

Just a little update on this endeavor...

I received the Motorcraft rebuilt motor. Was a bit of a task to get the old one out but with a bit of patience I was able to remove it. While everything was disconnected I plugged-in the new motor and checked for +12-volts at the washer pump connector (YELLOW/violet) wire. I got a good reading. Further, when activating the washer function on the stalk, I could hear a quiet 'click' in the motor (from the internal washer pump relay). But just to be ABSOLUTELY certain, I plugged the old motor back and performed the same procedure. There was no voltage at the washer pump connector AND no 'click'.

Satisfied, I reinstalled everything. To my chagrin, I got no washer fluid squirting. I figured perhaps the motor had, for whatever reason, gone bad from non-use? I purchased a replacement motor from a local auto parts store and plugged it into the washer pump harness. No whirring from the motor. I disconnected that new motor and pulled the existing motor from the reservoir. I tested both and both functioned perfectly. WTF?

Unfortunately, as this point it started to rain and I had to shudder my additional diagnostics. I trust the weather will soon yield to permit a permanent resolution. So far this has been an unnecessarily involved and time-consuming resolution.

 

[JRMedved]

OK. Better weather provided a means to further diagnose the washer pump issue. I removed the wiper arms and activated the washer function just to make sure I could still hear the 'click' of the washer pump motor relay. I confirmed it was still present. Next, I got under the front facia and disconnected the harness from the washer pump and grounded a test light to the hood catch...confirmed voltage to the harness connector. Since the harness there is too short to drop down under the car to access, and my big hands/arms will only allow room for 1 to access the harness connector, I removed the right inner fender/splash shield and was able to easily access the harness/connector. After a bit of fiddling, I determined that the female conductor pins at on both circuits was a bit stretched-open. I pulled out the yellow plastic conductor retainer and squeezed them a bit tighter and the reinstalled the pin retainer. Upon reconnecting the connector to the pump and activating the washer function at the turn signal stalk...

 

[hankfl]

Hi, just finished replacing the wiper motor on my 04/84k on the clock, to repair the washer. Tested the pump & multi function switch & were ok. Bad computer in motor, wipers worked fine & so does the washer now. Last thing to repair is the memory for the tilt/telescopic, any help would be appreciated. PS: the plastic gear on the motor was cracked.