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How To - Hardwiring Sat Nav Cable

1933 Views 19 Replies 12 Participants Last post by  colin-mck
Ive only had the car about 3 weeks but I cannot stand having dangling cables around and deep dashboard in the ST makes it difficult to get cables to reach. Based on previous posts regarding hardwiring road angels (credit to daviddabs) I had a crack at it this afternoon and took some photos on my phone along the way...

You will need:
A 12V ciggy lighter socket About 99p from ebay
<1m of wire. About £1.25 from ebay for 2m.
Fuse holder and fuse (this is optional - I didn't need it as my garmin plug has a fuse built in, but I would advise having a fuse in somewhere along the line)
Soldering iron and solder
Some tape
Wire strippers
10mm socket for earth bolt
Torx screwdriver
Torch and a flat blade screwdriver for poking wires through and finding clips on the panels
Cable ties

1. Remove panel under light switch - held on by one torx screw beside diagnostic port in the recess. There are several spring clips and the door seal doing the rest of the holding. Be gentle and use a flat blade screwdriver for a bit of extra persuasion.

2. The panel comes off as shown below. The diagnostic plug is held into the panel using two metal spring clips, these can be held back to allow the plug to be removed. This will keep the panel out of your way.

3. The cigarette lighter needs to be connected between a switched live and an earthing point so that that the accessory won't be draining the battery while the ignition is off. I couldn't find the big yellow ignition wire the daviddabs mentioned so I decided to tap into the switched live for the light switch. Removing the light switch assembly gives better access to the connector behind it. It is removed by squeezing the two big tabs at the back together and pulling the assembly out from the dashboard.

4. The wire colours don't make it intuitive to find a switched live. So I had to spend some time with the multimeter and switching the ignition on and off to find a suitable wire. I found the red/green one, on the top row, second from left to fit the bill. However this may be different for other model years. Double check by placing a multimeter between it and an earth (like the inside of the front cigarette lighter). Meter should read 12V when ignition is on, 0V when ignition is off.

5. Shave off a small section of the cable coating and solder on the live cable of the socket you wish to fit. Be sure to wrap up the joint well with good tape and also put a cable tie around both wires to prevent stress on the joint when everythings back together.

6. Attach earth cable to suitable earth. The earth bolt I picked is below door hinge level on the pillar. The bolt itself has a washer which cannot be slid off. The washer only make contact with the part below around its outer ring so the only place for the wire to be clamped in place is between the bolt head and the washer. This means that a crimped-on eyelet connector will not work. I simply curved the wire to be a tight fit on the bolt, then soldered it to maintain that shape.

7. The photo below shows the earth wire in place. The trim in front of this bolt is held on by one clip fastener on the footwell side and the door seal on the door side.

8. Soldering on the socket to the other ends of these wires and doing a bit of tidying results in this:

9. I plugged in the satnav cable and taped it to the socket to prevent it working loose. I then turned on the ignition to make sure the charging light was coming on, indicating it was connected properly. I cabled tied the excess cable in a bundle and cable tied the entire bundle in two places to prevent movement or noise over bumps etc.

10. Routing the cable up to the side of the dash is awkward to say the least. but with a bit of patience and strategic poking it can be done. I ran the FM traffic receiver up the A pillar by taking the door seal off.

11. Now just put the main trim panels back on again, taking care to line up clips and not to snag any wires. Start the engine and make sure all lights and your satnav cable all work.

As you can see it was starting to get well dark and cold towards the end so I apologise for the photo quality. But hopefully it gives you some idea of what to expect. Done in around 2hours, a quarter of which was devoted to finding the right live wire. Any further questions give me a shout. And Mods - feel free to stick this in the How-To section.

Happy bodging.

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Here's the final two photos of the satnav in position. I can't embed them as I've exceeded the max image number for two merging posts.
Great "how to"mate, good clear instructions, might have a bash at this sometime!
you only posted that last pic so we can see youve only done 400 miles

good how to tho matey
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Just about to try this myself but noticed that most folk seem to have taken feed from the back of the cigar lighter. Any real difference or any reason not to try the above approach?
I think the reason was that the cigar lighter stays on all the time, regardless of whether the ignition is on or not. Haven't checked it though. Light switch feed or ignition wire will power on/off with the ignition. Plus its much neater to have the satnav on the RHS of the dash so it handy to only have to pull off one panel to access the relevant wiring, rather than having to run wires the whole way across the cigar lighter.
Well ordered a socket and got the page all printed of so lets hope it stops snowing by the weekend
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Brilliant "how to", will come in useful. Thanks!
Nice instructions, well done. I dont like seeing wires myself, but it will surely help all the people that have these types of GPS units
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Just to confirm the same wire (top row, 2nd from left green/red (thick) ) is 12v live on the latest 59 plate aswell. Had to give up installing due to snow and light but wired in and working so far, just need to tape in place and put all back together tomorrow.

Excellent post. I'll move it to the 'How to guides' section.
Thats very similar to how i did mine , but took the feed from the cigar lighter . When the sat-nav is not in the car i tuck the cable into the air vent out of the way
i also took a live from the lighting for our lasses speed camera detector so it is not live when the car is parked up/it is ever left in the car etc.
I have a Garmin sat nav, which is powered by a Mini USB B cable, would it be posible, to just buy one of those directly, snip of the other end, and wire it directly into the 12V at the back, so omitting the need for a cigarette lighter socket, I'd assume I would need an inline fuse in this instance, and to find out which wires inside the USB were the 12 and 0 V wires?

The only other concern I have is possibly the sat nav runs off 5v or something, not 12, so the plug encorporate a TX of some form, to give 5 instead of 12?
No - chances are that the plug itself is the transformer that will either provide the correct voltage or at the very least regulate it. (e.g protect from spikes when ignition starts)

Edit - mean to say since USB is rated at 5v I would expect your satnav to be expecting 5v at its connection...
Yea I'd agree with Alan. If you talking about a standard USB cable then that will never work. Primarily because of the voltage and current difference. If you talking about a standard cigar lighter plug to mini-USB then it may work, but you'll lose the fusing inside the plug itself so would have to add another fuse in making it pointless. If you are talking about the full traffic reception cable than most of the mid and higher end garmins have then you definately have to keep the entire cable as is. The ciggy lighter socket a wire were very cheap (definately a lot cheaper than a second garmin cable) and despite it looking untidy, you can't see it so its all good IMO.
Fair do's, you think there is enough space inside the trim to house the lighter socket, and the sat nav cable, and just run the cable up the side and leave it there?
Yep plenty of room. Just make sure everything is secured so it doesn't rattle around or stress any of the connections. I also taped the plug to the socket incase that came loose.
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