Family has gotten a bit too big to fit in our '96 ZJ, so I picked up a 2004 LX 470. Traveled halfway across the country to find one in Nebraska that had avoided the East Coast salt. Overall it's in great condition for a 20 year old vehicle. Just two owners I think, and has stealership service records for the first part of its life. AHC is functional and recently serviced I think, and timing belt is in good condition. Replacement of the belt is high on the list of things to do anyway, just to be safe.
Good timing, since shortly after the transmission on the ZJ exploded. Still made it the few hundred miles back home though, so I can't complain too much.
Anyway, here it is when I bought it. I have plenty of bad ideas in mind, but will be starting with getting it in a factory-like state I'm happy with and can use as a baseline. Things are going to start out slow, but hopefully will become more interesting soon enough.
First order of business was to get some audio besides radio/cassette/CD. I have seen some modifications of the cassette player to accept input from an external source, but those methods have had some flaws. First, the audio chip from the cassette is always left connected, which introduces noise into the line, even if no cassette is inserted or playing. Second, these methods rely on the cassette player mechanism still operating, which draws power unnecessarily (a very small amount), and which has an unnecessarily high failure rate.
By completely disconnecting the audio chip and emulating the necessary inputs required for the controller to accept input from the cassette connection, these problems can be eliminated. The two inputs that need to be emulated are the reel rotation and tape position sensors (ES and POS lines). A 1 Hz 50% duty cycle grounding of the lines in question works for this, and I just used a 555 timer to generate it. Once the signal is active, grounding the tape load sensor line tells the controller to start playing from the cassette player.
This interaction with the load line doesn't need to be repeated after you've switched inputs, but under rare conditions that I haven't been able to identify yet, the controller will forget it has been told that a tape is loaded. This has only happened twice in several months, and during that time I did a bit of other electrical work. I have plans to tie one of the cassette-specific buttons to the load line so that this reset can be done easily, but want to try and identify the cause of the issue first. It might be as simple as the battery dying/being disconnected for long enough.
Here is the current setup using common standard components. I will put it onto a circuit board and use more specific components when I get around to it, but this has been working great in the meantime.
And here is a circuit diagram:
For this input, I soldered a 3.5 mm TRS cable to the head unit's inputs from the cassette player. In a later project, I want to do something similar with the CD/DVD player, but use it for Bluetooth instead. I think this will be a bit more straightforward than the cassette player, since it shouldn't have the same emulation issues.
I noticed that the grounding cables in the engine bay didn't have very good connections and were pretty corroded. There were also penetrations to the wheel well area with a welded nut on the wheel side. The grounding bolts and a few of the wheel well penetrations are M6x1 threading, and I had some appropriate fasteners lying around that worked well for the application. Anti-seize on threads, dielectric grease on the electrical connections, and some rubber-backed washers for the empty holes.
I'll be doing a lot more work on the electrical system, and there are some more penetrations I want to seal up for corrosion prevention in the near future.
I went ahead and replaced the cabin air filters with Fram CF11923. I've heard that a lot of these vehicles just don't have filters installed, but thankfully mine did and the inside of the housing was fairly clean. The Fram filters seem to be quite good, but they're expensive and Fram has been going downhill lately. I'll probably use the frames of the Frams to DIY the replacements. Probably foam prefilter, followed by granular activated carbon, then MERV 13+ particle filter media. It would be designed to allow easy washing of the prefilter and replacement of the GAC.
Good timing, since shortly after the transmission on the ZJ exploded. Still made it the few hundred miles back home though, so I can't complain too much.
Anyway, here it is when I bought it. I have plenty of bad ideas in mind, but will be starting with getting it in a factory-like state I'm happy with and can use as a baseline. Things are going to start out slow, but hopefully will become more interesting soon enough.
First order of business was to get some audio besides radio/cassette/CD. I have seen some modifications of the cassette player to accept input from an external source, but those methods have had some flaws. First, the audio chip from the cassette is always left connected, which introduces noise into the line, even if no cassette is inserted or playing. Second, these methods rely on the cassette player mechanism still operating, which draws power unnecessarily (a very small amount), and which has an unnecessarily high failure rate.
By completely disconnecting the audio chip and emulating the necessary inputs required for the controller to accept input from the cassette connection, these problems can be eliminated. The two inputs that need to be emulated are the reel rotation and tape position sensors (ES and POS lines). A 1 Hz 50% duty cycle grounding of the lines in question works for this, and I just used a 555 timer to generate it. Once the signal is active, grounding the tape load sensor line tells the controller to start playing from the cassette player.
This interaction with the load line doesn't need to be repeated after you've switched inputs, but under rare conditions that I haven't been able to identify yet, the controller will forget it has been told that a tape is loaded. This has only happened twice in several months, and during that time I did a bit of other electrical work. I have plans to tie one of the cassette-specific buttons to the load line so that this reset can be done easily, but want to try and identify the cause of the issue first. It might be as simple as the battery dying/being disconnected for long enough.
Here is the current setup using common standard components. I will put it onto a circuit board and use more specific components when I get around to it, but this has been working great in the meantime.
And here is a circuit diagram:
For this input, I soldered a 3.5 mm TRS cable to the head unit's inputs from the cassette player. In a later project, I want to do something similar with the CD/DVD player, but use it for Bluetooth instead. I think this will be a bit more straightforward than the cassette player, since it shouldn't have the same emulation issues.
I noticed that the grounding cables in the engine bay didn't have very good connections and were pretty corroded. There were also penetrations to the wheel well area with a welded nut on the wheel side. The grounding bolts and a few of the wheel well penetrations are M6x1 threading, and I had some appropriate fasteners lying around that worked well for the application. Anti-seize on threads, dielectric grease on the electrical connections, and some rubber-backed washers for the empty holes.
I'll be doing a lot more work on the electrical system, and there are some more penetrations I want to seal up for corrosion prevention in the near future.
I went ahead and replaced the cabin air filters with Fram CF11923. I've heard that a lot of these vehicles just don't have filters installed, but thankfully mine did and the inside of the housing was fairly clean. The Fram filters seem to be quite good, but they're expensive and Fram has been going downhill lately. I'll probably use the frames of the Frams to DIY the replacements. Probably foam prefilter, followed by granular activated carbon, then MERV 13+ particle filter media. It would be designed to allow easy washing of the prefilter and replacement of the GAC.
