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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 > Car Horn replacement blows fuse
Automotive - Car Horn replacement blows fuse
Expert: Ernest (Ernie) Kenward - 8/26/2008
Question
I am trying to replace my original car horns on my 2000 Dodge Dakota. I have hooked up wires to the new horns, which then work. But when I place them in the spot and screw them in where the others were my 20 amp fuse blows. I am using the original screw that held the first horns. I have placed electrical tape on the back of the new horns so the metal will not touch on the frame, but still the fuse blows.
Answer
The most likely possibility is that you did not pay heed to polarity or colour code when connecting the wires to the horns. It would appear that you connected the supply wire (supplying 12VDC via the fuse and perhaps from your horn switch as well, depending on the system's design - see note below) to that terminal on one or both horns that connects to the horn case and thus to the vehicle chassis ground when the horns are mounted.
Disconnect the horns and then use a low-ohms range multimeter or ohmmeter to determine (i) if there is continuity from the terminals to the horn case and, if so, (ii) which of the terminals has the LOWEST resistance to the horn case. Note that a low-ohms range meter will be needed because both connectors to the horn will exhibit quite low resistance, due to the horn coil being a high current coil that will itself be of very low resistance. If a continuity path and resistance reading are found, then follow the step in the next paragraph. If, however, both terminals offer very high (MegOhm range) or infinite resistance to the case, skip the next paragraph and proceed on to the NOTE below.
Similarly, the horn lead which is intended to provide the negative-side connection will be found to offer very low resistance to the vehicle chassis. This will be the lead that should connect to the grounded terminal on the horn.
NOTE: Check the leads for the presence of VOLTAGE. You may find that 12VDC is ALWAYS present on one supply lead to each horn. On the other hand, you may find that 12VDC is present ONLY WHEN THE HORN SWITCH IS ACTIVATED.
If one lead to each horn supplies 12V AT ALL TIMES (provided the fuse is good), then your horn system is the design type in which one terminal is connected to the supply and the other goes to vehicle chassis ground by way of the horn switch; closing that switch completes the negative-side path and operates the horn. These horns must ALWAYS have two terminals, and NEITHER should be connected to the horn case.
If one of the leads supplies 12V ONLY WHEN THE HORN SWITCH IS PRESSED (provided the fuse is good), then your horn system is the design type in which the negative side of the horn is always grounded to the chassis and the horn operates when the horn switch passes 12V to the horn positive-side terminal. Most newer horns of this type have both negative terminals, but many older ones will have the positive terminal only, and will rely on the physical mounting of the horn to the chassis to provide the negative side connection.
The overall evidence suggests that your horn system is of the second type, and that you have connected the switched supply lead to the horn's negative terminal.
Good luck ... EGK
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