Automotive/97 Chevy Cavalier

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Expert: - 8/16/2008


Question
I have a 97 Chevy Cavalier that my teenage daughter has been driving for the last few years.  After a minor "wrap around a mailbox" with the front passenger door (don't ask how) I have had the door re-set to where it closes properly, however, the overhead dome lights seem to be staying on much longer than they use to.  No matter whether it's someone getting in or out of either the driver or passenger front doors, the dome lights appear to stay on well beyond the few minutes that they should after closing the doors.  Any suggestions as to what to do?  I see this as something that can wear the battery down in a hurry.


Answer
First, I would check out the dome light switch on that door which was damaged.  Either the switch mount was modified by this adventure in such a manner as to keep the switch from being re-opened consistently by the closing of the door, or the switch itself is damaged and causing the same problem.

If that passes muster, then an alternative possibility (inasmuch as the doors on BOTH sides are keeping the dome light on for extended periods) is that the time-constant circuitry in the dome light's electronic controller has gone awry, possibly due to the disconnection of a bleeder resistor that normally would drain down the charge on the capacitor that keeps the transistor turned on for a period after the door switches have reopened.  Do note that I am taking the time to describe the old-and-simple analog circuit that could be used for this function, as a digital or processor-based dome light shut-off circuit should not have its timing affected one way or the other; it either would work or it would not!

"last few years"?  At what age did your teen-age daughter begin driving the car??  (Mine drives her brother's, which should save me from this adventure, and others, I hope!)

Cheers and happy hunting ... 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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