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kaisen kaisen is offline
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Join Date: Jan 2005
Location: Minneapolis
Posts: 7,482
Quote:
Originally Posted by lendaddy View Post
No, I agree. The full Size GMC trucks have some kind of issue with the running lights. They almost always have one out, it's weird. Is it a big deal? N0, but it is an interesting and correct observation.
[rant]

Well, from working with GM during that era (the GMT800 platform) I can tell you that a LOT of the problem stems from incorrect replacement bulbs.

Note the AC Delco 4114 bulb I referenced earlier? It is a glass-base bulb. It is exactly the same style and wattage as a clear 3157 turn signal bulb (plastic base). MANY early afermarket parts guides spec'd the 3157 as the replacement bulb because it was the correct connection-style, size, and wattage. In other words, it plugged in and lit up.

Trouble is, a turn signal bulb is used infrequently and intermittently. It doesn't have the chance to get hot. When used as a DRL, it gets so hot that the plastic partially melts and the bulb fails. Not the filament, the base. So using the incorrect 3157 bulb may cause a much shorter life span than the "correct" 4114 bulb.

Still to this day you can walk into some Wal-Mart, NAPA, or Autozone and look at their bulb guide and see the 3157 listed.

GM's thought here stemmed from what had been common practice to run DRLs as a lower-current run through the high-beams of the headlights. That was causing premature headlight failure and GM thought by switching to a dedicated light it would be safer than risking running with no headlight. And since headlight bulbs are $10-20 versus $4 for the correct DRL bulb, it would be a benefit to their customers.

So shame on GM for adding the cost of having a separate DRL. And shame on them for allowing it to be confused with the wrong bulb by the aftermarket, by clueless morons who will later blame the truck itself.

Mercedes-Benz, Toyota, and VW have all had similar issues with "almost-right" bulbs being used in the aftemarket and making problems for the manufacturer.

But it's GM's fault....

[/rant]
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Old 08-09-2012, 02:50 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #36 (permalink)