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Automotive/1995 Suburban Electrical

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Expert: - 8/31/2007


Question
Greetings Ernie,

I have a '95 diesel suburban 6.5. Had heads replaced 1 month ago. 1st I lost all interior lights, including tail lights. Still had head, brake lights, signals and hazards. While driving the motor would occasionally burp or hiccup. I found , I thought, a bare wire on the rear tail light assemble and taped it well. Now I had interior and tail lights....for a day. All fuses are good, all bulbs are good and new serpentine belt.
Today, on 401 (ONT) she started to hiccup, buck and then I lost all power, and lights. Coasted to a stop with no braking power. Tried to start and she cranked but would not turn over. Sun was directly in my eyes and I could not see the instrument panel to see if the gauge lights showed. Had her towed to garage. Tried to start again and she started, no problem.
I am wondering, if there is some other short or a bare wire somewhere that could possibly cause this.
Is there a test I can have done at an auto electric place?  

Answer
There definitely are definitely are electrical problems, suggested by the breadth and variety of bugs that have afflicted your Suburban.   Worse, the finding of bare wires anywhere is not a good indicator - it suggests that someone has carried out work on the system who is, to put it mildly, not proficient with electrical practices.

I am not familiar with the Suburban diesel but, from your problem description with that along with the relatively recent year of its manufacture, I would surmise that the control system for that engine is electric, and that electrical power continuity to the engine is required to keep it running.  Your vehicle being a 1995 model would confirm this, as it almost certainly relies on an electronic engine management unit of some type ...  

(The foregoing may sound like a no-brainer, but I am coming from the perspective of owning a 1984 Mercedes diesel which relies solely on mechanical controls to run and a vacuum control to stop the engine.  Electrical continuity is not required to run the engine; engine electrical equipment is confined to instrumentation, overload sensing, and the starting motor.  If the vacuum system fails, I can manually move the fuel rack to stop.  Electronic controls are great, but there is a definite benefit to having a fall-back mechanical mode to avoid an unintended shutdown and to get you home, if all else fails!)

Your best bet in the short term would be to check into a reliable auto electric shop (and I certainly could recommend one in Port Coquitlam BC).  Alternatively, you should get the shop manual and/or electrical diagrams for this vehicle.  Complete power failure suggests that a check of the main bus would be the place to start your investigation but, if I were in your place, I would do a bumper to bumper trace of the system. leaving no circuit unexamined.

I would start at Starbucks with a venti Americano.

Good luck ... 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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