C5 X7 amplifier power cables, trunk ground point

[raqall]

Hello fellas!

I am building a custom car audio system in my 2008 C5 X7. I installed the JL Audio's e6450 6-channel amplifier in the trunk where that "cloth-basket" was initially, on the left side. Now it is time to power it. The thickest power cable that fits into amp's socket is 25 mm² - that's what I bought (100% Copper cable, OFC, not CCA). The amp requires a 60 A fuse.

I am going to pull the positive wire through the firewall using a water-sealed grommet and install a 60A fuse near the positive terminal of the battery. Now the question I have is:
Shall I:
A) pull another (negative) wire through the firewall straight to the amplifier at the back
or
B) use a factory grounding point (I located one near the seat-belt tensioner at that top shelf of my Saloon)?

Will B) impact the electronics in the car somehow? The obvious drawback of A) is that I would have to fish 2 wires instead one.

[wheeler]

I haven't had a close look but im sure there will be an earth point near to where you are installing, probably for the rear lights. If not you would be far better off making your own earth point rather than run a separate cable from the battery.

Also be very careful where you pass the wiring through, I've seen may BSI units written off due to water ingress caused by poor installation of wiring through the bulkhead, The favourite on the Mk1 C5 was wiring for taxi meters being passed through the rubber grommet for the main wiring harness which was located right above the BSI.
EDIT: Original earth location picture added. This is for a saloon model, let me know if it's an estate.

[raqall]

I haven't had a close look but im sure there will be an earth point near to where you are installing, probably for the rear lights. If not you would be far better off making your own earth point rather than run a separate cable from the battery.

Also be very careful where you pass the wiring through, I've seen may BSI units written off due to water ingress caused by poor installation of wiring through the bulkhead, The favourite on the Mk1 C5 was wiring for taxi meters being passed through the rubber grommet for the main wiring harness which was located right above the BSI.
EDIT: Original earth location picture added. This is for a saloon model, let me know if it's an estate.

Thanks, great image!
My car is LHD, though I believe those locations are the same, especially at the trunk.

I have already made use of MC40 ground point, I installed the DSP there

On the other hand, why would they fish new wiring for those taxi-meters? I would just use a fuse-tap.

[wheeler]

My car is LHD, though I believe those locations are the same, especially at the trunk.

I have already made use of MC40 ground point, I installed the DSP there

I Selected LHD when I got the diagram, but I imagine they would be the same.

On the other hand, why would they fish new wiring for those taxi-meters?

Good question, I would use a feed inside the car too. The Mk1 C5 has been around since 2001 thought & piggy back fuses weren't that popular back then.

[raqall]

Actually my parents have the mark 1 since brand new in 2004, I'll be installing some aftermarket rear-view camera and parking sensors real soon

[white exec]

If I read you right (and I might have misunderstood)...
25mm²/60A-fusing for the power cable, and original cabling for 100mm/4-inch door speakers?

[raqall]

Well, yes. Actually those speakers are 165 mm.

I initially planed to go with some smaller/cheaper amp but I needed 6-channel amplification and that JL Audio was at a bargain price, so I bought it. Now I need to power it and it requires such power, that's why such a cable is needed.

I have everything done by now except for fishing that power wire, which I feel is the most cumbersome task of the entire process :/.

Already done: (RNEG2 install, car audio upgrade):

• RNEG2 screen with its bezel and head-unit installed
• roof console fitted with FAKRA GPS antena, USB extension cable for a soon-to-be-installed dash cam and mic for RNEG2
• custom harness made so not to cut the OEM cables
• Pioneer DSP installed and wired: two fuse-taps used (one for power, one for ignition-only power), custom harness utilised to receive the RNEG2's audio signal
• audio cables wrapped in protective loom and fished through the headliner away from the airbags, extra cables wired for additional speakers at the back shelf (for audible parking sensors)
• tweeters replaced with Clarion tweeters
• crossovers installed behind the glove box (LHD) and connected
• door pockets in all 4 doors treated with sound dampening butyl/aluminium mats, OEM moisture-barrier also replaced with butyl mats
• Clarion speakers installed on aftermarket rings (separated set for the front, coaxials in the back doors)
• custom-made sub-woofer enclosure fitted to the trunk's right pocket and shallow-mount subwoofer installed
• amplifier mounted into the trunk's left pocket

a lot of work! I will visit a car mechanic to ask for help fishing that power wire through.

Some photos I took throughout the process:

[raqall]

Thank you for your answers, the amp is finally installed!

I fished the hot-wire from the battery to the trunk going under left doors' kick-panels. There is just a perfect factory grommet, goes right through the firewall, more/less on the level where the steering wheel (LHD) is. One needs to look from below the steering wheel rack. I can post some pics if anyone interested.
I grounded the amp using factory ground location MC61 used for tail lights.

I've been listening for some time - no issues with the electronics of the car.

[Holmes]

I would like to see those pictures of the cable routing if you still have them.

[raqall]

I don't have the pictures but I have the car
Tomorrow I will make some pictures to show you how I routed the +12 cable from the battery to the trunk.

[pbdi4]

Hello. I came across your post while searching for a solution for my project.

I have a 2016 C5 x7 with the SMEG+IV2 nav and Philips HiFi factory setup and I'm facing an issue regarding the parking sensors sound volume.

How did you manage the parking sensors sound with the aftermarket dsp and amp? Did you bypass the sound somehow?

[raqall]

You can alter the parking aid volume using Lexia in RNEG settings. I don’t remember if I made changes or it was OK when left at default.

Is it too loud or too quiet for you?

[raqall]

I have added two dedicated (only for beeps) speakers under the sedan’s back shelf and wired them directly to the RNEG as rear speakers and set the RNEG balance to 100% front because I capture front only signal from RNEG with my DSP.

RNEG always mutes (or significantly drops volume) of the music before playing beeps from the parking aid at constant volume (selectable via Lexia) and I keep my Amplifier at fixed amplification/volume level so it is possible to set it so that it works just like OEM setup with no addded amps, DSPs or speakers.

[gab24]

Thank you for your answers, the amp is finally installed!

I fished the hot-wire from the battery to the trunk going under left doors' kick-panels. There is just a perfect factory grommet, goes right through the firewall, more/less on the level where the steering wheel (LHD) is. One needs to look from below the steering wheel rack. I can post some pics if anyone interested.
I grounded the amp using factory ground location MC61 used for tail lights.

I've been listening for some time - no issues with the electronics of the car.

Hi, old post but I give it a try as I'm struggling to find a way to route a cable from the battery of my C5
By anychance do you still have a picture of this pefect factory grommet ? If someone has aslo.
Regards.
Gab

[raqall]

Hi, I will take pictures tomorrow and post it here