And a shortage of blinker fluid

When you say that the electrical system of a car is “flatly insane,” it’s easy to jump to the conclusion that said car is some misbegotten British box whose electrons are flowed sporadically at the whim of Lucas, Prince of Darkness. “With a monopoly in place,” says the anonymous Wikipedant, “Lucas proceeded to supply electrical equipment that was commonly cited as the best reason not to buy a British car.”

Yet somehow, without buying from Lucas, the Americans managed to duplicate the experience, as Ric Locke explains:

The electrical system is quite flatly insane. Things work or not according to some scheme I have not yet identified, probably having to do with the phases of the moons on some planet in the Andromeda galaxy. For instance, the turn signals — which are driven by the computer, not anything simple like a flasher module — are supposed to have an audible signal, a soft beep each time they flash. That started working one afternoon last September, worked perfectly for a day and a half, and hasn’t worked since.

Most annoyingly, from time to time it just stops. While traveling down the road the engine quits as if the ignition had been turned off — no coughs and spits like fuel starvation, no “run down”, no nothing; just one moment running, the next moment not. So far it has not yet failed to start again once the transmission lever is set in Neutral and the ignition is switched off and on to reboot the computers, but it’s annoying as can be. (No, I don’t think it’s a Windows operating system. That’s barely possible for the time period, but the logo doesn’t show up anywhere.)

Early-90s Mazdas showed signs of this latter, which was eventually traced to thermal overload in the ignitor. This part was theoretically available separately, but part places in general and dealers in particular would rather have sold you the entire distributor.

On a car of a Certain Age, however, I tend to suspect that the wiring harness has assumed the general shape and inscrutability of the Flying Spaghetti Monster (pasta be upon him), and only divine intervention can save it.





5 comments

  1. Ric Locke »

    7 January 2011 · 9:16 pm

    No, it isn’t British. It’s worse, It’s GM. It doesn’t have a distributor, at least not a rotary one with a cap; it has three coils, and the coils aren’t grounded. Each end goes to a spark plug; when it fires on the cylinder coming up on compression it also fires on the counterpart coming up on exhaust.

    General Motors has always done electrical systems >>almost<< well. What makes it "almost" is the control the bean-counters have over the process. They always end up saving a couple of cents too much on the components. The result usually works fine until the car gets old, and the corrosion, vibration, and heat work their way on the connections.

    You used to see it most prominently on grounds. GM was almost the last manufacturer to add a ground wire to the harness. Their philosophy was that the metal of the car was by God ground, and that was good enough. Some bright engineer parlayed bad grounds into blinking marker lights — "ground" the tiny bulb to the hot wire of the turn signal. I know without any contact whatever that the guy who figured that out had been frustrated by the taillights on a '63 Chevy. On an old GM car, if something isn't working the first thing to try is to get a clean ground.

    On my car they overcompensated. It has at least six separate, independent ground circuits that all lead back to a common bond point. This is very good practice with anything that uses computers, but once again they saved half a mill more on each connector pin than they should have.

    Some generous soul has scanned the service manual and posted it on the Web. If I didn't have that it would be hopeless — but it's an image PDF with no index, and no way except brute force to translate manual section designations like "8D-204-2" into PDF page numbers. I am currently filling a notebook with cross references. Wish me luck. I am bloody f*ing determined to at least get the gas gauge and trunk release working.

    Regards,
    Ric

  2. CGHill »

    7 January 2011 · 9:28 pm

    Sheesh. At least Nissan was kind enough to give us a separate coil for each cylinder. (Not that they last all that long; my car is on its second replacement set, and a set installed runs $700ish.)

    Still, “phases of the moon” might be more of a factor than I’m willing to admit. I had a ’93 Mazda that used to quit shifting in the rain — but not always.

  3. Ric Locke »

    7 January 2011 · 10:42 pm

    My boss is a tool and die maker, a highly skilled and specialized subset of “machinist”, and has the usual shop-floor love-hate relationship with the designers. He said something about engineers being anal retentive. “Jerry,” I said, “Engineers are supposed to be anal retentive. When an airplane falls out of the sky or a bridge falls down it’s because the engineers weren’t anal retentive enough.”

    Sounds like the engineers at Nissan weren’t quite obsessive enough about what all needed to go into the coils. One of the reasons my engine has three coils is that you can overdesign them enough to make them last a long time and compensate for wrong polarity on the plugs, and still come out cheaper than installing six separate ones. It’s a fine, nearly definitional example of what “engineering” is all about.

    Regards,
    Ric

  4. CGHill »

    7 January 2011 · 10:59 pm

    I think we can safely say that Nissan didn’t overengineer these coils.

    The other weird issue on this model is that occasionally the idle air control valve will fail, and it takes the ECM out with it. I have yet to experience this particular delight.

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