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Automotive/98 Buick Park Ave Ultra Rear Wind. Defogger

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Expert: - 3/12/2008


Question
I have a 98 Buick Park Ave Ultra and my rear window defogger quit working. My RWD switch still lights and my heated mirrors still heat. I heard a rumor that ther might be a junction plug that gets corroded down the side of the car somewhere but I don't know where to look and I can't find a wiring diagram for this circuit(it is not in my repair manual) My cruise control went out about the same time frame but I don't want to chase two things at once. Any ideas where I might start?

Answer
Chasing down two problems at once is not highly desirable, but can be productive if, for example, it points to a problem in a supply bus or fuse feeding both.  However, I rather doubt that any cruise control system would share a circuit with a high-draw item like a rear window defogger!

Given that the defogger controls work back to the switch and telltale light, I would agree with your assessment that there could be a corroded or otherwise damaged (thermally, due to current draw through increasing resistance) connector in the feeder going back to the defogger.  This is all the more plausible given the likely passage of the feeder through unheated and possibly damp passages in the car.

The manual not being much help, you might be able to get a wiring diagram from the resource used by many auto-electric technicians, that being Mitchell's On-line service resource.  I would find a friendly auto-electric shop and simply see about getting him/her to print out a page or two that contains the wiring information.  Most of these guys have plenty enough work, and thus usually are happy to help out when they get a query from someone who knows what they need and when it takes little time to accommodate the request.  This can generate good will for future work anyway!

By the way, I have exactly the same problem with my Mercedes 300CD nearly-vintage turbodiesel two-door hardtop.  I haven't dealt with it yet only because I baby the car by driving it in good weather anyway.  My work with that car thus far has been confined to engine preventative maintenance, some custom electrical instrumentation, and adding a pod that nearly looks like it belongs there for a "boost" gauge for the turbocharger.  Lots of fun.

Hope the above helps.  If you strike out on the wiring diagram, do get back to me.

Cheers ... EGK

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Ernest (Ernie) Kenward

Expertise

The challenges I most enjoy are thoughtful technical questions of a trouble-shooting nature in both electrical, power electronic and mechanical systems, mainly automotive but also machine control and small-machine PLC applications. Please note, however, that I am NOT a walking shop manual! I DO, however, make it a point to have those manuals and other service literature for those vehicles I DO own, and highly recommend that anyone serious about maintenance or modification of their vehicles do the same; MOST of your answers WILL be found there. For that matter, I do NOT go out of my way to acquire shop manuals for any vehicle I do NOT own! That being the case, any general query to me along the lines of "What is the meaning of this code read from the ECU of my 2015 XYZ?" or "Where is the fuse for the windshield washer pump found?" (try your car's electrical distribution panel for a start!) will not go far. What I do offer is a pretty good collection of literature, insights and hands-on experience with 1950s to 1980's Ford products (plus a developing database of information and practice with the Mercedes diesel cars), along with an engineering perspective and the ability to design and implement custom control, electrical and mechanical subsystems for vehicles. For that reason, I am happy to make my thoughts and efforts available to those who are of like mind and/or are seriously making a point of learning about their vehicles. Use the Opportunity to Learn!

Experience

A key skill in my work and hobby pursuits both is STRATEGIC TROUBLESHOOTING. I am a senior instructor in Electrical Engineering Technology at a leading Canadian polytechnic, my areas being Electrical Power and Industrial Control, electrical and electronics design and manufacturing, and AutoCAD and related CAD/CAE software - plus equipment problem-solving and new equipment design and prototyping. Hobby-wise, I have 30-plus years of experience in auto restoration, mostly in electrical and mechanical systems. Ongoing projects include a 1959 Edsel Corsair, my 1978 Ford E250 class-B motorhome conversion, and the care and upkeep of my Mercedes 300CD. My vehicles become engineering test beds for electrical and mechanical upgrades as ideas present themselves. This includes the design and production of circuit boards to restore or enhance features for which no OEM replacement parts are obtainable, or where better specifications or reliability can be had via newer concepts. Regarding the E250 RV conversion, I designed and continue to revise a custom power distribution system, managed by a Programmable Controller (PLC); this has made most revisions as easy as uploading new firmware as I develop it. The "mini" PLC is a powerful device for custom automotive control systems. One good example (there are many) would be the Moeller "Easy Relay"; these offer a wealth of control, monitoring and variable-and-status display options for such projects. A good example project which has worked well is that one for my RV noted above, which has been on the job - revised in firmware only - for a decade now. It is a load management and charging control system to avoid the sulfation-induced early failure that often befalls deep-cycle batteries used in RV power applications. The battery installed in 2003 lasted long enough to more tnan pay for the PLC that contributed to its longer life ... and the PLC will be there for the next battery as well!

Organizations
IEEE - senior member ... past WCC Student Activities; SME - senior member ... past chair, greater Vancouver chapter chair 318; Edsel Owners' Club - have served in various capacities on chapter executive during seventies; have been Power and Driveline resource on the Edsel Owners' Club "E-team" for more than a decade.

Education/Credentials
Graduate of UBC

Awards and Honors
Certificates of appreciation from IEEE and SME for work in student and chapter activities

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