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Automotive/95 Sentra won't start
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Question
Hello! I have a 1995 Nissan Sentra. I have replaced the starter several times in the past year. In the last month, if the car wouldn't start, I'd tap the starter and the car would start up no problem. That is not working anymore, in fact, the car does not want to start at all. I had the battery checked and that was fine. When the key is in the ignition and in start position all lights are on and bright. Any ideas as to what could be going on?
Connections at the starter appear to be becoming intermittent, although it is also possible that the problem is with the starter's contactor, or possibly with a connecting cable. Intermittent problems are sufficiently random as to be misleading, and it could be that the tapping-the-starter temporary fix was a bit of a red herring. A bad contactor and /or cable is less work to replace, if necessary, and is therefore a good place to start the investigation.
Disconnect the cables from the contactor and inspect the opened terminations. Any discolouration or burn marks, on the terminal posts or on the cable terminations themselves most likely at the terminal connecting to the lead from the contactor, could be indicative of this type of problem. Cleaning, filing off any pitting, and greasing (Fluid Film or similar# connections before reassembly and tightening to specified torques usually will bring back reliable service. Do note that any parts that are particularly burned, or corroded, should be replaced. A low-ohms resistance check of the contactor itself, or a measurement of voltage over the contactor's high-current terminals while attempting to start the engine, can indicate internal contact problems with the contactor if either readings are excessive.
If the problem is not found with the contactor nor with the connecting cable and its terminations, check the terminal post at the starter itself. Again, look for any discolouration or burn marks, and repair or replace as necessary. If no problem is found there, then you might consider removing the starter for inspection, and also inspect the mounting flange where the starter connects to the chassis common at the engine Pitting around mounting bolt holes could be indicative of an intermittent connection there; this is not common, but should not be discarded out of hand if everything else has proven to be okay. Too, the problem could well be within the starter #brushes at limits), in which case that can now be readily tested and verified, or be seen to need replacement.
Best regards ... 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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