matt-c

Sat Nav Aftermarket Gps Build

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Decided to follow up on this sat nav build, since I never got round to it. I bought the 7" housing a couple years ago, and bought a cheap Chinese GPS off eBay, then when it got here, realised it didn't have an AV input (for reverse cam that I also want to install), and when I tried to send it back under their "no quibble 14 day UK distance selling regulation" return policy, they would only accept returns to China, even though they were advertising as a UK seller! Complained to eBay and got full refund, inc postage, and was able to keep the GPS! So they've both sat here for a couple years doing nothing, until I decided I should really give it a go, hopefully with help on the wiring (my achilles heel) from a work mate, after I put in the physical build work.

So, the other night I ripped it apart;

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Did a quick. slot in, test fit with the tablet;

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And then set about ripping the tablet apart - the connectivity is all on the side of the unit, and there isn't room inside the housing to plug anything in. I'd have to rip it apart to get to the PCB anyway, and I wanted to relocate it if possible, thus avoiding having to solder directly onto it for power etc

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With the PCB loose, I can easily plug a USB cable in for power without having to solder directly onto the PCB, thus making the USB port still operational if I need to plug it into a computer for updates etc.

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Then, I broke a wire off the PCB! Turns out to be the wire that lets the Battery charge, so I can still boot up at the mo, but not charge. Not the end of the world because it will have constant power once in the car and wired in

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Anyway, with a couple holes drilled in the back casing to cable tie the PCB down, I glued a couple of crude wooden blocks to the sides of the housing. Reason for this is it holds the tablet perfectly snug and tight, but allows me to pull the tablet out if need be - more on that later;

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The reason for being able to slide it out is 1) in case I need to plug it into my computer for anything, and also 2) this is just the test bed. Because this GPS owes me nothing, I'm happy to experiment with it (I've also compromised the screen ribbon cable, so it's a bit iffy displaying an image), but if we can get this all working how I'd like (which is to try to replace the GPS on/off switch with a trigger, so that it powers on with ignition and off again with power cut) then I'll buy a newer one, this time with the AV input for reverse camera, and possibly also with Bluetooth so I can (hopefully) connect my phone to it for handsfree (the idea is I can plug the 3.5mm jack from my Grom into the tablet, and possibly solder a separate mic onto it, rather than use the internal mic, which of course will be inside the housing.

Also, I spotted this http://www.ebay.co.uk/itm/361119746945?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT which would be good to connect to the microSD card slot on the PCB, run it behind the head unit and under the console and maybe have it come out in the ashtray? That way I can load stuff onto a regular size SD card and hot swap it on the move, rather than having no access to the mSD slot without removing the entire tablet.

Wiring is my problem - I can't solder and I'm useless with electronics! But hopefully a work colleague is gonna help me try and get it all working. Plan is to wire the power for the housing to a computer molex connector, and then tap into the cars wiring for that power, to another molex - making it completely removable, rather than hardwired (should I want to sell it or move it to another car later on). As for power for the tablet, the plan is to simply use the USB to cigarette power adapter, but wire a female cig socket (probably into the wiring for the existing cig lighter) and just mount it behind the dash and plug directly into it - again making it simple to unplug if need be.

And hopefully, with the newer tablet, I might be able to get this logo to be the default splash screen during boot (can't get it to work on the current one)

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Project on hold now, as one of the wires for the power switch also broke - so now I can't turn it on, or charge it! Guess I'm gonna have to buy a soldering iron and brush up my (non existent) skills!

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I see there's a lot of interest in this project LOL. Oh well, I'll just keep "blogging" about it as I go...

So while I'm waiting to see if the GPS PCB can be fixed, I made up some temp wiring to test the nav housing - yep, had it 2 years and not even powered it up to see if it even works! I used to have a nice little 240-to-12v box, but I'll be damned if I can find it (think I binned it actually :( ) so I just hooked up directly to the old Battery that came out the Lexus this winter! Wired the perm and switched live pins together, to positive, and ground pin to negative, and it works! Using the same wiring, I took the illumination negative and ground pins to Battery negative, and the illumination positive to Battery positive, and they work too!

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And this is my intention for wiring the housing into the stereo wiring. Unless I can get hold of the standard plug (was quoted nearly £25 by a breaker!) I'm gonna use a computer molex connector, so it's easily plug and play if I need to remove it;

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Then for the GPS power, I'm just gonna spur a female 12v cig plug off the existing one by the gear shift, and just plug the supplied USB adapter into that - again, easily unpluggable.

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Couple small updates;

1) managed to get hold of a loom plug for the housing, but unfortunately it's missing a couple of the pin connections I need. Seems that even though the plug is identical, earlier models (5" version) doesn't have the same pin connections, so there's some blank spaces where I need pins. Hopefully it will be rectifiable, but if not it's back to the original plan to use the molex connector, and just wire the negatives (ground plus illumination - to the same pin in the connector)

2) Bluetooth is now struck off the list. Although my Grom unit has USB, iPod and AUX (3.5mm jack) connections, and you can switch between them using a key sequence on the head unit, you can't actually have the plugged in at the same time. Tested this last night by having my iPod playing (iPod connection) and Iphone also plugged in (AUX) with a vocal speech playing (to replicate voice directions for a nav, or the callers voice if I was taking a call. Whilst both will function at the same time - iPod music is playing and I can hear the speech over the AUX, the volume is halved for both devices. Unplug the AUX jack and the iPod is restored to full volume. Considering that I'll be using the iPod 99% of the time, and the AUX would only really be used for taking a phone call (I almost never use voice directions on sat navs) this is no good to me. Shame they aren't isolated and would only work by switching inputs on the Grom, but I guess it's not to be. I'd never use the GPS media functions for music, as I have iPod for that - with much better control and sound - there's no reason to use video playback either; 1) because I can't see the point in converting video files to the correct codecs and resolution, putting them on a card and playing them back while driving anyway, and 2) because there's no point having video with no audio. So there's probably no real reason to get the card reader extender cable thing I linked to either, as the microSD card slot would solely be used for maps now, so I shouldn't need to get to it, to hot-swap.

So we're back to only two core functions; touchscreen turn by turn offline maps (ideally TomTom if I can hack it to run) and reverse camera (which if version 1.0 works, then that will be coming in version 2.0)

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Just ordered up some more connectors, this time for the table power supply. My plan is to hang a 12v socket off the wiring under the centre console that goes to the cig lighter. Then run the 12v socket up being the stereo, and plug in the standard power adapter that came with the tablet. Reason for this is not having to mess around soldering in resistors etc to get the voltage down from 12v to 5v. The reason for getting some more connectors (BEC type 2pin) is so I can hide the cig plug and power adapter behind the stereo, and just feed a pair of wires up around the air vents, terminate them in a connector, and then have the cable coming from the table (out of the nav housing) terminate in the other connector. That way, if I need to remove the nav housing, it's as simple as unplugging two connectors - the molex connector (for nav housing power) and the BEC connector for tablet power. It'd be nice to have something less bulky than the 12v socket and adapter behind the stereo, but so long as there's room it doesn't really matter so much. I was going to use a USB bullet adapter and just use the supplied USB cable, but I did that with a phone charger solution in my work van, and it wasn't a roaring success (it provided power, but not enough to charge the phone up properly. May well have been a rubbish USB cable, but either way I'm not going down that route for this project. I don't want to fry the cheap chinese PCB with incorrect voltages/ampage!)

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Pulled the dash apart today to have a look at the wiring I'll need to tap into and to check space for routing cables and the power adapter

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Found a nice little nook I can tuck the power adapter and 12v socket into, and there's plenty of cable on the end of it to route up behind the heater vents. Will need to lengthen the wiring on the molex harness to give enough slack to wire to the radio plug and be able to pull the housing out and not have it snag, but that should be simple enough, with a metre of 1.5mm wire, as I only need to extend each wire by 20cm or so. Need to order up some heat shrink to tidy it all up with - hoping that 3mm will be ok to fit over the crimp terminals (to insulate them inside the housing plug socket) and 6 or 8mm to cover the bundle of wires from the molex plug down to the radio plug. Gotta decide on colours now

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Still not further on, as I still need to hook up with my mate to do some soldering and try to find a work around for the on/off switch in the GPS tablet. I've discovered that if I bridge the points where the press switch used to be, the tablet will power up. However, if the points remain bridge, it will turn itself off again after a few seconds - and it can only be rebooted by removing the bridge, and rebridging it. So, I need to find a work around that will allows these two points to remain physically bridged, but only allow a power flow through them fir the first few seconds, then after that either divert the power flow somewhere else or interrupt it. Something like a pulse power circuit, or in layman terms (and I'm a proper layman when it comes to this :D ) a "gate"

On a brighter note, I got hold of the original plug that fits this nav housing, only to find after receiving it, the pin connections aren't quite as they should be. Seems it's from an earlier model, and although the plastic plug is the same, it's missing some connections for the pins I need to use. So I reverted to the original plan of cutting up a computer molex connecter - one end of which will have female spade crimps on the wires, which will attach to the pins on the nav housing, and the other end of which will be hard wired into the stereo wiring. Turns out, that's easier said than done, as the smallest crimps are just that teensy bit too big; they can be made to fit, but they touch. I could insulate them with heat shrink, but I'm still not 100% convinced.

So I looked out a brand new ISO harness I've had in a drawer for years and years and never used (think it's ISO to mk4 Escort plugs) and hacked that about until I got two of the female pin receivers out, with their wires. Not a direct fit into the Lexus nav plug, but a bit of bending and squashing with some pliers and I got them in, and with a bit of careful angling, the plug fits in the nav, and all connections are made - tested it hooked up to a car Battery and (same as the video above) and all functions work. So that's pretty cool, as all I'll need to do now is put a half metre or so of wiring on each of the 5 wires, insulate and wrap them, then they can be spliced directly into the stereo wiring for power, ground, and illumination

Ordered me some heat shrink and a "my first soldering set" off eBay, so when that arrives I'll have a go at extending the wires, fit the two-pin plug to the GPS power wires (so that that can be plugged and unplugged at the dash-top end too) and hopefully won't be long after that, that we can start on trying to hack the power button on the GPS tablet

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Well done Matt, Following this with interest as I am starting on the same project, except I have a TomTom Start60 to go in. Just figured out the wiring from another forum.

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Thanks. I'm on a bit of a hold at the moment because I'm waiting to hook up with my mate who's much better at soldering than me, and hopefully he's gonna be able to figure out how to turn the press on/off switch into an auto on/off switch. Everything else is done - it's just a case of splicing into the stereo harness for the 5 wires to the housing, and the cigarette lighter harness for power for the GPS. But no point doing that until we can get the actual GPS to power up.

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Same with me Matt. My IS200 is my second car. (Got an Audi A6). I am trying to figure out my Battery problem. Got ERR3 so bought a nice Sony double din and the amp bypass cable. If I drive the car every day, its fine. Leave it for 3 days and the Battery is flat. I do notice that the clock stays illuminated all the time after the install. Disconnect the bypass cable when I'm not using the car and the Battery is fine???? Once I get this sorted out, I can confidently wire up the Sat-Nav

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There's something you have to do with the bypass cable - cutting one of the yew wires and connecting another one. I don't know as I've never used one. Have a search on Google, as it's been covered plenty of times.

The wiring on the housing is easy - three wires for power (perm live, ignition live and ground) plus two more if you want the buttons to illuminate (just a positive and negative). Wiring to give power to the TomTom is easy too - just tap into the wiring for the cig lighter - it's a switched live so won't drain the Battery charging the TomTom when the car is off. The main problem is making the TomTom come on and turn off automatically with ignition - unless your model has an option for that. Mine doesn't, which is where the headache is

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Thanks Matt, I'll have a scout about. My TomTom Start 60 auto powers on when it gets power from the cig lighter

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Not a lot going on at the mo, but did spend a few mins sorting out the multiplug I got for it. Even though it's the right plug, seems there's more than one configuration for the pins, to do with year of car, size of screen, remote control type, etc. The one I got wasn't the right pin config I needed, so I used a couple pins from an ISO lead and made them fit (as mentioned a few posts above). Anyway, I tidied the rest of the plug by trimming back what wasn't needed, and had a quick connect up to test everything works as should

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The red and black plug above is for the USB power connection to the tablet. I put it on a two-pin plug so it's easily detachable should I need to remove the whole thing from the car

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And some coloured wiring turned up today, along with a loom sheath to tidy it all nicely. Just need to figure out a path to run the mini loom down from the dash top to the HU plug. I was originally gonna go to the side and drop straight down, but with a test fit, the plug sits much further back, as originally the wiring was part of the main harness that runs above the heater matrix. So I need to figure out a path to run it down behind that, without having to take the heater matrix out! Cos that'd be a ball ache!

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Well a very productive afternoon - it's all in and working! No pics of the final finished article because it got too dark, so here's a couple from the install.

First, the unit plug was soldered to the wiring I bought, to make a "loom"

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With that done, it was out to the car and the bit I was dreading - cutting into the radio plug wiring. My poor virgin Lexus - the one I've had that hasn't been messed with and was all stock (well, apart from the mirror closure kit I did the other week - so I suppose at least that popped it's cherry!). Following the pin out guide, we cut and spliced the wiring with the new nav loom, and at least did a nice tidy job of it, using heat shrink and sleeving to make it look as factory as possible

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Here's where the pics end. There wasn't an awful lot more to see, although I do wish I'd got some of the next bits. After the above, we wired the female 12v socket to the wiring for the original 12v socket (cig lighter) under the lower console, to provide power for the GPS tablet. For this we just tapped into the live (switched) for the cig plug, and crimped the negative to a ring terminal and used one of the bolts going to the gear shift cover. Then we had to figure out what to the with the GPS tablet itself, in regards to turning on and off. My work mate (who did all the soldering for me, cos I suck at it) resoldered the wires that broke off the PCB when I've been messing around with it (the charging wire from the Battery, the positive wire from the Battery (that broke while we were handling it today) and the two wires from the on/off button. We then tested it to see what was what - basically one of the switch wires was a constant live, showing about 3.5-3.7 volts, and the other showing nothing - make the connection by depressing, and holding, the button and it completes the circuit, turning it on - press and hold again and it powers it off. Problem was, we couldn't see an easy way to give the PCB a short burst of 3.7v when turning on, or again when wanting to turn off. We looked at using the motor - so that when it opened it turned the tablet on, and when it closed it turned it off, but there were two problems with this. Firstly, the motor was kicking out between 9 and 10 volts, so too much power, and secondly, the red and black wires from the motor weren't positive and negative, they're forward and reverse! We ummed a bit about connecting up both wires (forward to turn on, and reverse to turn off) and using resistors to step down the voltage, but then decided against at. as 1) that's a PITA, and 2) having both wired into the same wire on the tablet's PCB would probably short it out. Also, the power button on the tablet power button acts as a home button - so when you're in any app (such as sat nav, music app, etc) a single short press of the power button takes you back to the home screen; just like an Iphone. So, had we wired in using the motor, then pressing the tilt button would constantly be kicking the tablet back to the home screen.

So...... We decided to extend the wiring from the tablet PCB power button down behind the dash to the heated seat and TRC button panel, and fitted a teeny tiny little press button. So although the tablet doesn't power on and off with ignition, it's a simple little button press, which is tucked out the way where it can't be seen or knocked, and I also retain the "home button" function too - useful for changing the backlight brightness without having to exit the sat nav app to do it in the main screen.

More pics of it up and running in the daylight on Wednesday, as although I'm off this week, I'm being a hero and going back into work tomorrow to help out with the backlog! In the mean time, here's the "skeleton" in and working in the car;

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Next on the list - swap out the actual tablet to one with an AV input (as mine turned up sans AV input) and run a reverse camera to it, and then try to hack TomTom to run on it. Be nice if I could find a way to change the boot up splash screen from a Manga cartoon girl to the Lexus logo too.....

Anyway, finished pics in a couple days :)

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In the car pics

Home screen

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Nav app

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And of course, the obligatory video

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Brilliant work,i am getting round to doing mine next week,planning on just using the in car charger to power the tablet on an off though.Hope yours is still working well?

Will keep you posted on how i get on

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Hello everybody.

Just want to say Good job.

Matt, when You go into the device features, do You see model m515.. I think internal memory is not enough.

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