Archive for October, 2007

project schedules: the 80/80 rule is still in effect

You may be familiar with the Pareto principle, otherwise known as the 80/20 rule. When applied to project schedules, the first 80% of the project takes 80% of the budgeted time. Slightly less well known but still true, is the corollary: the remaining 20% of the project takes the other 80% of the budgeted time.

Have you seen this often when writing software, writing a book, painting a room, organizing your finances, or basically any other non-trivial project? Why does this happen? I think it is well-meaning hard-working people who are optimistic. People fail to be pessimistic enough about complexity and roadblocks. As a result, a large increase in effort is needed near the end of the project to keep it on schedule. Our optimism gets us in trouble.

So what do we do? Be pessimistic in your time estimate. Then double it. Seriously.

It’s better to finish earlier than expectations than later. As I keep telling students: with schedules, it’s more important to be accurate than optimistic. Also, take this quote from Star Trek III: The Search For Spock:

Kirk: “How long to re-fit?”
Scotty: “Eight weeks. But you don’t have eight weeks, so I’ll do it for you in two.”
Kirk: “Do you always multiply your repair estimates by a factor of four?”
Scotty: “How else to maintain my reputation as a miracle worker?”

things i wish i knew before working marcelk 23 Oct 2007 No Comments

cars: replacing the dash lights in a Honda Odyssey

I have a 2000 Honda Odyssey, and although it has been a wonderful vehicle, it is at the age where the dash lights are starting to burn out. So my clock backlight has failed, along with the lighting of several buttons on the dash. When I went to get parts at the dealer to replace the clock backlight, it turns out that the person in front of me in line at the parts department was there for exactly the same reason for the same model. It’s relatively easy to do, if you know where to start. That’s what I’ll explain here. I started taking the dash apart to access the clock backlight, but you’ll get to the other lights along the way (except the instrument cluster).

First, the bad news. The clock doesn’t pop out forward from the dash. It pops out backwards behind the dash. So don’t try to pop out the clock from the front of the dash, you’ll just end up damaging the dash. This means to access the clock you need to take out 3 large pieces of the dash. The good news is that most everything just pops out. What doesn’t pop out is held in only with standard screws. Once you understand how it works, you’ll say “ah, that wasn’t so bad.”

Click on these thumbnails to get a full-size image.

wedge to pry the dash apartThe first two major parts of the dash just pop off. It’s not difficult, but it’s not obvious what to do. I started prying next to the steering column and gently worked my way across. I started at similar points on both sides. Then you can slip your fingers behind and gently work it until it pops completely loose. For the prying I used a plastic/vinyl flat tool that happened to come from my kitchen. I would recommend against a hard tool like a screwdriver because you’ll leave marks. The plastic kitchen tool I used left no marks.

right wiresOnce you’ve popped it loose, don’t try pulling on the fascia to get it completely away from the dash. Each piece of fascia has switches with wiring that goes behind the dash – those wires are still connected. The wiring for each of these switches can be disconnected from the switch, and once that is done then you can move the fascia all the way away from the dash. Each wiring connector has a tab that locks it onto the switch, so don’t try disconnecting the wiring by force. Instead you’ll need to find the tab for each connector, depress the tab (they do take a bit of effort), and then the connector should slide off with an unforced pull or a little bit of wiggling. DO NOT pull by the wires; instead you should be pulling by the block connector while depressing the tab. Some wires have more slack than others, so you may find that a certain order of disconnecting/reconnecting is needed.

For the right fascia around the stereo, the shortest wires are for the interior light switch and the fog lights (if installed) – do those two first. Then you’ll have more slack for disconnecting the three wire groups for the climate controls. My van does not have the satellite navigation.

rear view of right fasciaHere is a picture that shows the back of the right fascia, so you can see where the wires connect to.

For the left fascia around the sliding door buttons, the wires were about equal length so just do them in the order that you can reach.

Now the bottom half of the dash on both sides is removed.

screws for left side of top half of the dashscrews for the right side of the top half of the dashNext comes the top half of the dash. This is all one piece. It is held in by screws along the bottom, and tabs across the top. Get a phillips screwdriver and remove the screws (don’t lose them). Then gently work the top half of the dash out. It is not connected to the instrument cluster (speedometer, etc.), just the border.

wires for clock and hazard blinkersAgain, be careful of the wires for the clock and hazard blinkers – you must disconnect the wires using the tabs before pulling the fascia all the way away from the dash. Once you’ve gotten this far then you have completed disassembly.

rear view of clockNow that you can access the rear of the clock, the bulb comes out with a quarter turn of a screwdriver. It looks to be the size of an LED, but I think it is a regular but very small bulb. You can also verify it is burned out by using a multimeter to test for continuity. Put the new bulb in (should cost about $3 at the dealer). While you are there, check the rest of the bulbs in the switches and the climate controls. I think there are two different kinds of bulbs: the common one is for backlighting, and the other is for “on” indicators such as the cruise control and fog lights.

For the top half of the dash, position it in the correct place, reconnect the wires, pop it in, and replace the screws. Do the same thing for the left and right fascia, except that there aren’t any screws. Just remember to reconnect all the wires, or some things will stop functioning.

You’re all done! See, that wasn’t so bad. Don’t you feel proud that you didn’t pay the dealer $90 in labor?

life tips marcelk 05 Oct 2007 20 Comments