Automotive/radio will not work

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Expert: - 9/5/2007


Question
I recently changed my spark plugs, distributor, and wires in my '99 Dodge Dakota 4x4 5.2 liter engine.  Before I started I removed the battery wires and replaced them when I finished.  Everything works great except my radio does not work.  I checked and replaced the fuse for the radio but it still does not work.  Any suggestions on what else I could try to fix the problem?

Answer
Is there any possibility that you might have inadvertently reversed the battery connection at some point in the work, however briefly?  This is a long-shot question on my part, and I ask it only to be complete.  

All but the cheapest electronic devices are protected against reverse-polarity connection misadventures and, in any case, if HAD made a reverse connection error at the battery terminals, it is very likely that this would have taken out two or more diodes in your alternator's rectifier stack.  You would know if this happened, as you would not be getting any output from the alternator, and would shut down in fairly short order as the battery discharged.  Not to worry - your comment that "everything works great" (except for the radio) would lay this to rest (unless you spoke too soon!)

Another point to investigate: Might there be some sort of reset required on the radio - setting its clock, for example - before it returns to normal operation.    

Failing that, it could just be a matter of coincidence.  Check out the power connector to the radio for presence of voltage.  If you don't get the expected 12.8V or so (battery only, on Accessory position of the key), then trace back to the fuse.  Be sure that the fuse terminals are clean.  In fact, it may well be that the simple act of pulling apart the connector at the radio and then plugging it together again will clean off oxides and clear the problem.  If it does, make the fix more permanent by applying some electrical contact grease to the connector pins.  This same material can be used on the fuse terminals.  

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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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