Mysterious malfunction

[driller]

Subject: 2006 Town Car

The wife was telling me during dinner the wipers on the Town Car came on magically today while she was driving. They wouldn't shut off. She stopped for an errand and they shut off when the car shut off and did not come back on magically when she returned to the car to come home.

Great, I'm thinking a short somewhere or possibly a bad multi-function switch.

Following dinner, I proceeded to take out the garbage and heard this thump-thump in distance. I went to investigate and found the Town Car sitting in the driveway with the wipers cheerfully running. The radio was on as well.

I returned to the house to get the keys and a flashlight. Looking in the owners manual, I located the fuse for the wipers and that successfully stopped the wipers. I had to pull the delayed accessory circuit breaker to get the radio to go off.

I'm not even sure where to begin.

 

[tixer]

Is there any chance that thing has rain sensing wipers that were heretofore disabled?

 

[SCTBIRD1173]

Well that sounds interesting... Hope you don't have to pull out too much hair trying to figure this one out! :err-what?:

 

[steve]

It's possessed

 

[driller]

It doesn't have rain sensing wipers.

I took the easy way out and dropped it off at the dealer. It needed service anyways.

We'll see what the diagnosis is and go from there. My thoughts is the Lighting Control Module is suspect?

 

[chris2523]

whatever controls retained accessory power (RAP) would be suspect as well.

 

[driller]

Apparently, the car was struck by lightning.

I received a call from the service advisor and after he almost gave me a stroke with the rundown of the estimate, I had him email me a copy.

Customer states WIPER BLADES AND RADIO COMES ON THEIR OWN - EVEN WITH CAR OFF AND LOCKED *INTERMITTENT
ISSUE* ----- TECHNICIAN VERIFIED CONCERN. TECHNICIAN TESTED WIPER MOTOR AND FOUND INTERNAL SHORT IN MOTOR. FOUND WIPERS STUCK ON HIGHEST SETTING DUE TO INTERNAL SHORT IN MULTIFUNCTION SWITCH. TECHNICIAN TESTED RADIO AND RADIO TESTED OKAY. TECHNICIAN INSPECTED GROUNDS AND WIRES AND FOUND LIGHTING CONTROL MODULE SHORTED

I guess my question is how does something like this happen? Three individual items shorted out simultaneously? :eek-large:

 

[billcu]

How can there be a short in the wiper motor if the motor still works?

 

[driller]

How can there be a short in the wiper motor if the motor still works?

I wondered the same though I am aware of the translation that often occurs between the tech and the service advisor. I'd really like to talk to the tech that worked on it.

I can *almost* believe the Lighting Control Module going bad but I think they may just be throwing parts at the wiper issue because I know from experience the lengthy troubleshooting charts involved with the wiper system. I'm just not convinced it's coincidence that the two separate systems failed independently at the same time.

I think I'll just get my complimentary oil change and hope my Lincoln "Owner Advantage Rewards" balance covers whatever diagnostic fees there may be and bring the car home for repairs. Tammie will just have to suffer and drive the Navigator for a while.

It looks like I'll be getting intimate with the EVTM and service manuals for the Town Car in the near future.

 

[LeoC2]

Hire an exorcist, it'll be cheaper.

 

[BlackIceLSC]

I would install a cheap used known-good multifunction switch.
we know the wipers are controlled through this part
we know the lights are wired through this part(hi/lo beams/passing beams)
that is the ONLY "correlation" those two "functions" share in a mechanical part


just my 5 cents

my 94 lost brake lights one day...
bulbs = good
BOO switch = good
CHMSL = worked....
but the outer brake lights did not.

turned out to be the MF switch....the brake lights are wired through that switch because of the HAZARDS.

Just give it a shot and see

 

[driller]

I finally got time to revisit this.

I studied the manual and EVTM diagrams. Logic told me what most likely happened was the cowl drains plugged and the wiper motor got flooded shorting it out. I could see some leaves and debris through the cowl vent.

I discarded the pages of diagnostics in the manual along with the dealer's diagnosis of an internal short in the wiper motor, a shorted out multi-function switch and a short in the lighting control module. I ordered a wiper motor from NAPA (since I get a company discount there and it appears only reman units are available anyways).

After disconnecting the battery, I removed the wiper arms and cowl covers and then proceeded to remove the cowl assembly to access the wiper motor assembly. I noted during disassembly it did not appear to have ever been disassembled before and even the harness plug (which was external to the cowl assembly) did not appear to have been recently disconnected. I did find the drains plugged and a distinctive 'high water mark' in the cowl assembly and on the wiper motor.

I replaced the wiper motor, cleaned everything up and reassembled it all. I plugged in the fuse for the wiper module and reconnected the battery.

My theory evidently was correct as the wipers now function as they should. I hope the reman wiper motor lasts. It wasn't that particularly difficult of a repair, just a PITA to gain access to actually remove and replace the wiper motor.

I suppose what irks me is the dealer diagnosis. I was somewhat confident not all 3 components would simultaneously fail. My guess is replacing the wiper motor, multifunction switch and lighting control module would cover all the probable failure points... at my expense. If I were to be cynical, I guess they could've just replaced the wiper motor and charged me for all three?

 

[tixer]

Great follow-up, JP. And great troubleshooting..

I'm glad you got 'er all fixed up. It's interesting that the dealership "detected a short in the wiper motor" but failed to do anything about it..

 

[driller]

It's interesting that the dealership "detected a short in the wiper motor" but failed to do anything about it..

I'm beginning to wonder about the local dealership. I've bought a few vehicles over the years from them and used their parts/service department before with minimal complaints.

However, a couple years ago or more, they were bought by a growing auto group that owns several dealerships of various makes around the area. They recently have moved to a new facility in a upscale retail development on the other side of town. I noted after the move their shop rates went up fairly significantly and that's understandable I suppose. I just hope their service department retains my trust going forward.

 

[Lvnmarks]

I doubt the mechanics saw any of that up change. The experience in the shop might be on a decline due to that.

Glad you got er fixed, there is a special sense of accomplishment when troubleshooting and finding the issue.

 

[driller]

... there is a special sense of accomplishment when troubleshooting and finding the issue.

Definitely. :thumbsup:

Along with the knowledge it was done right and all the parts were cleaned proper prior to reassembly (even though the rest of the engine compartment was dirty ).

 

[steve]

Most shops are just part changers today. The don't troubleshoot, not profitable. Most people rather have them change the parts then to spend a few hours chasing down the root cause and geting charged $100/hr for the labor then have to pay for the fix.