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About 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 for every car in existence! While I have been described by colleagues and students as having an encyclopedic knowledge of automotive and transportation equipment in general, I do NOT have a collection of shop manuals and detailed specifications for every vehicle in existence! What I DO have is a good collection of literature 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 similarly making a point of learning about their vehicles. In regard to manuals and specifications, your automotive parts shop, automotive parts houses and, often, the public library are good resources for these.
I also have a good track record for trouble-shooting and solving emissions problems in older carbureted vehicles. Doing the latter requires that one has the interest and makes the effort to learn how combustion systems are intended to work and can appreciate how the various systems and settings interrelate - there are no short cuts nor "quick fixes" here; this is a job definitely doing properly and with one's eyes open, as the payoff is not only an honest pass of an emissions test, but an engine which will perform with its intended power, economy and reliability!
Experience
One of my key skills both in my work and in my hobby pursuits is STRATEGIC TROUBLESHOOTING. In addition to having been the Power and Driveline resource on the Edsel Owners' Club "E-Team" for the past several years, I am a senior instructor in the School of Electrical & Computer Engineering at the British Columbia Institute of Technology. My main area is Electrical Power and Industrial Control (including PLC applications and programming), and I round this out with course development and teaching of courses in electrical and electronics design and manufacturing, and in AutoCAD and electrically related CAD/CAE software.
From the hobby perspective, I do automotive restoration of all aspects of automotive systems (1959 Edsel Corsair since 1972 and 1978 Ford E250 van since 1985), class-B motorhome conversion (my reason for reworking an E250) and electrical and mechanical custom upgrades as viable ideas and opportunities present themselves. I have designed and produced custom circuit boards to bring back or add features to vehicles when no new parts were obtainable or where a better specification or operation could be had using a more modern circuit. I designed, installed and continue to revise a custom electrical system for my E250 motorhome conversion and, since 2002, this has been managed by an onboard industrial PLC (programmable controller) which has made many revisions since as easy as plugging in my ThinkPad and uploading new firmware.
I am also remanufacturing a sixties-vintage travel trailer, and am using a Moeller 620 mini-PLC in that application as a battery manager.
Also keen on vintage cameras, telecommunications equipment, railway passenger equipment and locomotive technology, fusion cuisine and renaissance music and chorale activities.
Current project - and the one which drew me to this website - is my "new" but very nice Mercedes 300CD, one which developed a minor vacuum problem ... I do not have a shop manual for it yet, so thought I would pose a question ... thanks!
Organizations
IEEE - senior member ... WCC Student Activities chair 1985 - 87
SME - senior member ... greater Vancouver chapter chair 1988-89
Edsel Owners' Club - have served in various capacities on chapter executive during earlier years
Education/Credentials
B Sc in Physics, UBC
Awards and Honors
Certificates of appreciation from both IEEE and SME for work in student and chapter activities
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You are here: Experts > Industry > Transportation and Logistics > Automotive > trailblazer voltage problem/idle & A/C
Automotive - trailblazer voltage problem/idle & A/C
Expert: Ernest (Ernie) Kenward - 10/6/2008
Question
Sir,
We own a 2006 trailblazer xlt 2wl.drive w/an I6 engine. it has 48Kmiles. Recently, when at a stop or redlight, the voltage would drop from 14 to near the redmark of 10volts, the a/c starts to blow hot, and the lights would dim slightly. If you increased rpms, while at a stop, the voltage would rise accordingly and the a/c would "kick back in". The check engine light is on. after running above 1K rpms, either driving or just in park, the voltage would return to 14 and the a/c cold. Note that the rpm idle speed never fell below 500 rpms unless I pressed the accelerator the entire time(s). The battery was original. I checked to see if the battery had corrosion or needed water, but it was maintainence free. I believe disconnecting the battery cleared the check engine lite. We brought the trailblzer to a mechanic. He connected it to the diagnostic and put in a new battery. He said it had no codes, but ran fine with the new battery. I started the tblzer and the rpms varied from 400-600, voltage holds at 12, and the a/c & lites work fine. When you increase the rpms, the voltage rises to 14 (which I know the manual says it should when you increase rpms). The check engine lite is back on, the rpms vary at idle speed, and the voltage falls off from 14 to 12 when the rpms decrease as you come to a stop.
Shouldnt the voltage always be at 14? I own a '96 1500 4.3 v6, have a chevy work truck w/a v8, and drive other chevy vehicles at work and w/friends. What am I missing as I believe the vehicle is still "broken"?
Thanks,
Chris in new orleans
Answer
Modern alternator regulators will initially (on engine start-up) provide 14.5 volts plus to the battery in order to equalise its cells and to provide a fast bulk charge to make up for the starting motor draw. Thereafter, the voltage will taper off to 13.8 to 14.2 volts, a voltage below the battery's gassing point, in order to take on the electrical system load while providing a nominal charge to the battery.
The regulator is there to provide voltage regulation and does this by modulating the alternator's field excitation. The alternator supplies power as a function of the mechanical power it takes in from the engine, a product of torque and speed. At idle speed (500 rpm or so), most alternators will develop full voltage under very low load, but the voltage will often drop below the regulation setpoint if the connected load draws more power than the alternator can produce at idle speed. Note that most gasoline engines will initially run at a "fast" idle during the warm-up stage, and alternator output can be greater during that time than it would be once the engine has settled to normal idle.
It ids possible that the alternator itself may be faulty, perhaps an open rectifier diode, or it may just be that its mechanical drive - the belt - is just loose. These are the things that you might want to check out.
Shop manual information would be good to have to speed diagnosis and to avoid assumptions.
Good luck ... EGK
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