Tuesday, May 28, 2013

Fixed: Toyota Highlander Brake Light

Note: This post has nothing to do with wireless. 

Toyota Highlanders are well made cars - I bought a 2004 for my wife who later upgraded to a Sienna minivan, so I took the Highlander for myself.  It's at 100,000 miles and still going strong.  However, apparently they have a known problem where the brake lights on one side will intermittently stop working.  I've had people pull up next to me at stop lights and tell me I have a light out, then I get home to find the light is fine.

Then recently the light went out and stayed out.  I replaced the bulbs but they remained out.  Fuses were fine, my trusty Fluke 77 said voltage was getting to the assembly.  Posters in Toyota forums said that dealers are asking $40 - $140 for diagnostic, plus possibly $300 to replace a "circuit board"...?  Sounds like a scam to me.

I did some searching online and found reference to how the contacts on the bulb holder will get compressed and not make proper contact. (Kudos to Berto for the original post and Kujath for the photos.)  Kujath suggested using a flat-blade screwdriver to bend the contacts a bit, but I think a needle-nose pliers works better since you can control the amount of bending.  I did both bulb holders and the lights are working just fine. 

Monday, May 27, 2013

TK-890 Amateur Radio Mod

Over the past weekend a friend of mine asked if I would help him convert his Kenwood TK-890 mobile to work on the ham bands.  I wasn't sure how successful we'd be, since most every online search came up with at best little information or at worst flat out statements saying "Nope, can't be done."  As it turns out, it can be done.  Kudos to Tim K for his notes posted to Radio Reference which gave enough hints to make this happen. 

In general this is how it went.  My friend wanted his radio to work on the Bay-Net repeater system, which operates 443.225 with a +5 MHz TX split.  TX was fine, but RX was giving a steady "beep-beep-beep..." which indicates PLL unlock.

In the PLL section, under the copper foil, are three adjustment pots: A = TC302, B = TC303, and C = TC301.  (Don't ask why they're out of order.)  According to the Service Manual, Pot A sets the PLL for the low end of the receiver range, Pot B sets the high end of the receiver range, and Pot C sets the TX PLL.  The goal is to monitor test point CV with a voltmeter and adjust for minimum voltage during RX and TX.  This requires re-programming the radio's test frequencies to match the band of interest, so you'll need the KPG software and cable. 

Once we had the PLL voltages minimized for RX and TX, I found that the radio's TX frequency was way off, so a frequency alignment was needed.  This again required the KPG software - for some reason we couldn't get the radio into Panel Test/Tune via the control head.  It was easy enough with the KPG, once we realized you need to press "Enter" to lock the modified value. 

Other things like adjusting the BPF and checking deviations should be done.  In the end, the conversion was very easy and the radio is working well on the UHF amateur band.