Automotive/thanks!

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Expert: - 4/7/2009


Question
Your Question was:

i know your probably not an expert on this,  but i have a 99 grand am.  i put in new fog lights a few days ago and they worked for like  15 seconds and then went out.  the fuse is fine and the relay looked ok.  any ideas?

Following is the reason:

The problem could be anything from an intermittent switch or connector to - more likely, given the failure after an initial period of current draw - a break in a bond at a connector, switch or even at the fuse that is initially in point contact but which opens on heating.

There is no need of expertise here, other than skills in fundamental circuit analysis and a feeling for the physical shortcomings of aging connections!

Good luck ... EGK

Expert: Ernest (Ernie) Kenward


thanks a ton man!  im gonna buy a new switch,  whats a good process icould do to solve this issue.  i hope its the switch cause i got no where else to look.  your the man!  thanks so much!

Answer
Thanks yourself!  Thanks also for the chance for me to take a second look at your question, and noting this time that this was a NEW fog light installation.  That can help focus the answer a bit better.

So this new installation worked for the first few seconds, and then that was it - nada!  The fuse you either chose or added to power these lights didn't open, so the "weak point" was elsewhere in the circuit, and I would expect that it will turn out to be a loose or otherwise bad connection that effectively "fused" open as a result of the current draw.  One way to find this problem would be to carry out a section-by-section continuity check with an ohm meter or DMM - the section where continuity is not found will be the site of your problem connection.  Include the switch in that continuity check, before you replace it.

As to the relay, its action - or inaction - will also help you to localise where to look ...  

If turning the fog light switch ON (along with the headlight switch, if your lights are wired to be available to augment the headlights, per practice) causes the relay to operate, in which case you will hear its contact or contacts close, then all the circuitry from the source of supply through the switch(es) through to the relay are functioning as intended, and your further investigation will be on the contact side of the relay.

If the relay does nothing, then the problem probably lies in the switching circuit that controls the relay.

In either instance, do your check in whichever circuit is not working.

As to good process , I always recommend that one get the vehicle's shop information, including wiring diagrams.  Having the specific information always simplifies repairs and custom upgrades alike.

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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