FITTING AN OEM WIDESCREEN SATELLITE NAVIGATION SYSTEM
IN A NON-NAV LEXUS GS

Click each photo to view a bigger version.


Navigation unit end of wiring harness.  Some colours on these plugs don't match the ones in the Lexus wiring diagrams, but this doesn't matter as long as the correct pins are used!  You can't see in this picture, but one of the three-core cables has been marked with tape at each end so that they can be told apart.  All connections have been soldered and taped, with each pair of wires cut at a different position so that the joints are staggered instead of being in one fat bundle.  In addition, staggering the joints reduces the risk of a short-circuit if any of the tape slips off.


The same connections sleeved and taped.  Because of the staggered joints there's no big bulge in the harness and the sleeves fit over nicely.


This is as much as can be done without installing the cables in the car, as you don't want to try routing the plugs themselves through the car's cable channels!


A pair of DPDT relays have been fitted here, end-to-end.  This is not required when fitting the navigation system, I've added these to be able to replace the navigation unit's RGB+Sync signal with my own, part of another project.


The same pair of relays taped up.  Note that two grey cables exit to the right.  One of these is the cable entering from the boot, the other contains the three wires that go to the combination meter and diagnostic port.  The original wires have been pulled out and the three wires threaded through instead.  This gives the wires greater protection.  The two grey cables to the left come from the relays, one goes to a SCART plug and the other carries the power feed for the relay coils.


The connections are starting to take shape now.  The black cable that leads out towards the top of the picture is another example where the original wires have been pulled out and the sleeve re-used for protection.  This one contains the REV and SMUT wires from the navigation unit in the boot.


The three-core mains cables make a stop-off here on their way to the amp, so that power can be fed to the navigation unit in the boot.


These are the plugs that go into the back of the combination meter, otherwise known as the instrument panel!  The violet and blue wires head just out of shot to the right, then double-back towards the radio.  As you can see in this picture, all of the connections are being soldered.


The white plug on the left plugs into the clock.  The brown wire is tapped into the wire that's used to dim the clock when it's dark, and does the same job for the touch-screen display.


I had a spare R3 plug, so instead of cutting this one off I just tapped into the wires feeding it.  Also visible in this picture is the PKB (parking brake) wire, I've taped it up instead of connecting it, but will be connecting it soon as it's required to access the diagnostics screen.


These two wires are easy to miss, as they don't appear in the radio or navigation wiring diagrams!  Leave them out and the buttons on the display won't illuminate.  Connect them and the buttons can be dimmed along with the rest of the dashboard lights.  Nice!


Here's the spare R3 plug, connected to M3.


All plugged in!


Don't forget the gateway ECU!  Fortunately the plug for this is already there, it's just a case of plugging the box in.  It should come with a bracket, but if it's from a LHD car it won't bolt in place.  Fortunately it'll fit roughly where it belongs (up above the accelerator, next to some other modules) without rattling around, if you unclip the relay that's already up there and clip it onto the slot on the gateway ECU's bracket.
Also in this picture you can see the orange wire that connects to the diagnostic plug.  This was fed through the same grey sleeving that went to the combination meter, then dropped down.


The N-MU (navigation mute) pin is missing from the S10 plug in non-nav cars, or at least it was on mine!  Fortunately I had a spare R2 plug which had three spare pins that fit S10, so I scrounged one...


...and popped it in!  If you need to do this you'll need a small jewellers' flat-blade screwdriver to release the plastic bar in both plugs and pop out the pin.


The wires to the front-right speaker are cut and the two three-core cables connected to the ends.  Get the cables the right way round or the navigation unit will be talking to the amp instead of the speaker!  The green/yellow cores were cut off behind the radio, and the same is done here.  Also visible in this picture is the REV wire.  I've not bothered connecting it, so I've looped it back and stuffed it into the sleeving out of the way.  The orange SMUT wire has been connected to the newly-fitted N-MU pin.


All taped up and plugged back in.


It boots!


It controls the aircon!


It plays music!


Oh, and it navigates!  The project has reached its destination!