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Automotive/dashboard door/trunk open light remains lit

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Expert: - 5/25/2011


Question
Good day Ernie – a question for you on my 2002 Buick Century, please.
Recently, the dashboard door/trunk open light has stayed lit in my Century.  I have repeatedly made sure the trunk and all the doors are closed, yet the light stays on.

I am not sure, but I believe it may be related to the trunk. At one point, the light remained lit and upon opening and closing the trunk the light went off, though a short time later it went back on.

What could be causing this and how can I repair it?

Shortly before the light went on, I replaced the bulbs in my third stoplight, the one that sits on the deck beneath the rear window. While this may be unrelated to the door/trunk light remaining lit, I wanted to mention it in case there is any correlation between the two.

Thank you very much for your time and any information you may be able to provide.

Regards,
Jim

Answer
Without knowing any of the specific details of the Century, I can nonetheless suggest that the problem likely lies with a normally-closed held-open (NCHO) limit switch being loose on its mount, our of adjustment, or possibly breaking.

This would be a switch located so that its actuating lever or plunger will be contacted and then held by some actuating tab on on the trunk hinge or latch mechanism.  Should that tab be damaged, ie: bent, or the switch itself be loose, failing or fragmenting, then the necessary action to open the contact will cease to happen, probably sporadically initially, but more definitely and permanently as time goes on.

It is possible too that this is a magnetically-activated switch, rather than mechanically-operated as above.  In that case, a loose switch could still be at fault, letting it fall away from the proximity of the magnet - or the magnet itself could have vamoosed!

In either case, your task is to check out the trunk mechanisms to find that switch!  Once you have found that, you can probably decide on the next move from there.

Good luck and best regards ... 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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