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Automotive/power locks won't open
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Question
Have a 99 Chevy Venture, power door locks will lock, but not unlock. Only way to get out of car is to turn off engine. Lock just fine, though. Don't know if related but have been having to change turn signal and brake light bulbs pretty often. Also have on and off problem with ABS light coming on, when foot on brake both turn signals on dash light up, sometimes gas gauge goes up and down.
There is no one simple "magic answer" to this, rather, the multitude of symptoms suggest a general problem with the car's instrument panel circuits and likely the instrument power and possibly main power distribution systems as well. The problems appear to be due to intermittent cross connections. This can suggest a damaged wiring harness or one or more damaged connectors, exposing conductors, or something metallic being loose and moving around freely within a circuit enclosure.
Signal and brake light bulbs having to be replaced frequently suggest either or both of (i) excessive voltage and (ii) loose mounting of the luminaires bearing these lamps making them subject to physical shock and vibration - either situation will shorten the lives of the lamp filaments significantly.
Troubleshooting these problems is best done with the vehicle schematics in hand, as that would provide the best way of ascertaining what each of the affected subsystems have in common in terms of location and circuit. This would help to localise the region of the problem and ultimately the problem itself.
In the time being, I wonder what voltage the car's main power bus rises to when the alternator is running, and if there are any significant transients present. A moderately to fully charged battery will provide from about 12.25 to 12.8 volts or so in a car that has not run for a few hours, up to about 14.6 volts just after start-up, to about 13.8 to 14.3 volts after the engine has been running for fifteen minutes or more, sooner if the ambient temperature is warm. Voltages in excess of 16 volts or so begin to noticeably shorten lamp life (Power varies as the square of voltage), while transients going to tens or hundreds of volts can cause faults to insulation and semiconductor devices.
The foregoing is general, the specific details of Chevy products not being part of my library. It does give you possible avenues to explore however.
Good luck ... EGK
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Answers by Expert:
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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