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Discussion Starter · #1 ·
A quick reminder that all the "idiot lights" on our dash light up when you turn the key on for a reason. That's so you can make SURE THEY WORK.

Why was I reminded of this? Because I was halfway between two small towns on I-10 in southern Texas when, seemingly for no good reason, my CD stopped working. Then my ABS light came on. Then the traction system indicator. And then the ABS indicator. Yes, my alternator was no longer charging, but I wasn't aware because I hadn't noticed that the charging system idiot light had burned out some time prior to this trip.

The good news is that I managed to keep going until the engine flamed out about 1/2 mile short of the only rest stop for 80 miles in any direction. I was able to coast into a parking place with a huge handicapped area just ahead (ensuring room for the tow truck). Some quick tests with a meter showed my battery was down to 4.5 volts (!) and stranger still, still dropping (I'd expect it to start recovering once you turned off the car and removed the load). Pulled the battery terminal and my ohmmeter showed 0.5 ohms to ground (which would indicate a draw of 25-30 amps, a HUGE amount of current to be drawing from the battery). I suspected the alternator, and figured that if that was the problem, it would probably be unusually hot... a drop of spit on the case sizzling away instantly confirmed that. Pulling the heavy "output cable" from the alternator let me make sure that was the problem (it was).

My wife found a rebuilt alternator in Fort Stockton (35 miles further east) and it was across the street from a hotel (not luxury, but I could walk to the O'Reilley's auto parts store from there). My RV roadside assistance plan covers our "little cars", so they dispatched a flat bed to pick us up. While I waited, I pulled the alternator (after checking on mdxers.org to make sure you could do that without removing the fans and/or radiator - it's snug and fiddly, but very do-able). I also discovered that the socket set I bought for the car didn't have a 14mm socket (!!!!), which is necessary to remove the big (stubborn) lower mounting bolt for the alternator, and for twisting the accessory belt tensioner to get the serpentine belt off. A local Harley-riding motorcycle club was hanging out at the rest stop having a few adult beverages, and couldn't resist wandering over to see what I was up to. Five minutes later, using a borrowed 9/16" socket (equivalent to a 14mm) and some tugging and grunting from a couple of their guys, the alternator was out.

Got dropped off by the tow truck on the "empty side" of the roadside hotel, nose out in the parking place, and walked across to get the replacement alternator (and a 14mm socket). It was getting dark, but I managed to get the new alternator in and the car fired up in short order. In the end, it was a minor inconvenience rather than a "real problem", given that we were able to wait at a nice, clean rest stop (where I could wash my filthy hands after pulling the alternator), with help from some bikers. Even better, it was a cool 71° because of a thunderstorm that had rolled through a few hours prior to our arrival. So we arrived at our son's place half a day late, and $180 poorer, but still very happy with our (normally) very reliable MDX. No way anyone could have predicted this failure, but it would have been nice to know the failure was underway before it started shutting down the various systems. Check those idiot lights when you start your car!
 

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Discussion Starter · #3 ·
216,000 plus now. It's been ridiculously reliable. I've done a lot of preventative maintenance (lower control arms and tie rods up front, rear shocks, O2 sensors, etc.), but almost nothing has failed. I had a rear window regulator fail suddenly (cheap and easy fix), and a high pressure power steering line start weeping (cheap and fiddly fix), as well as a dash vent controller act up (required pulling, cleaning, re-lubing and adding a washer for better operation).

The way I figure it something "electrical" (not mechanical) went belly-up in my alternator, so it's probably not something that would be a whole lot more likely at 200,000 miles than it would at 20,000 or 400,000 miles.
 
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