XJ40 ( XJ81 ) 1986 - 1994

Aftermarket stereo install

Old 12-11-2018, 01:50 PM
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Default Aftermarket stereo install

Hi all,
The six speaker factory stereo in my '90 Majestic was sounding pretty crappy and I would like some modern conveniences like CDs, blue tooth and so on.
I began my install this afternoon using my Alpine CDE133BT from an X300 I parted out.
I have a copy of the wiring diagram and had no problem finding the two front door speakers and the right rear door speaker using the AA battery trick.
I can't find the connection/s for the left rear door speaker and the under seat speakers. Am I missing something?
Any advice, direction and instruction?
Thank you all,
Old 12-11-2018, 08:15 PM
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Late XJ40's (like 94's, VDP's etc) don't have under seat speakers, just door and tweeters on the back deck - maybe X300's don't have under seat speakers either? Or maybe no rear door speakers and the what you think is the right rear is actually the underseat subwoofer?

Just guessing ...

Maybe check the x300 forum audio guys.

Old 12-12-2018, 08:47 AM
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Hi, thank you.
The two rear are the under seat subwoofers and they have to be replaced.
They are completely deteriorated and useless. I did, however, get the right subwoofer to respond
to my battery trick. I can't get the left ear door speaker and left rear under seat sub to respond to my battery trick.
My car is almost 30 years old and I will replace all of the speakers.
I'm really not surprised; the job is greater than I wanted, but it is what it is.
I'm installing my Alpine CDE133BT to drive the four door speakers and I'll use an Alpine KTP445U to drive the under seat
Old 12-12-2018, 08:39 PM
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There is one issue that I recall having which applies to these XJ40s.

Something about a common ground for the front speakers? I recall having to pull new speaker wire to the front doors when I replaced the Alpine unit with a JVC Arsenal.

Old 12-13-2018, 09:25 AM
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Could be, I'll turn my new Alpine on for a sound check before I finish up.
While I was locating the speakers with my AA battery I could not get the left rear door speaker and sub to crackle.
Using my Fluke multimeter I located a common ground in the plug...?
Old 12-13-2018, 11:38 AM
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Roger: I installed a compact Kenwood KSC-SW11powered subwoofer. I just placed it on the parcel shelf between the headrests. I am happy with the added base. It is very small and looks good in that space but you can move it elsewhere in the interior. It definitely won't deliver the thump of a trunk mounted 12" but it significantly improved the mid-range base notes for me. I am toying with the idea of trying box speakers placed on the same parcel shelf, behind the headrests. I would disconnect the four rear speakers if I used enclosed speakers so I can supply the most power to each box. I would imagine I might be able to find 5x7s. I wish I had the door panels of a '94 VDP as I believe Jag bumped the size to 5.25" which provides better sound than the 4" that I have. Ren
Old 12-13-2018, 01:22 PM
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When I bought my car the door speakers were deteriorated. I purchased a Pioneer head unit and matching speakers 4 5" for the doors and 2 5.5" for the sub woofers.
The Pioneer head unit came with 4 paired outputs (which I used for the doors) and 2 sets of RCA outputs. 1 set of RCA output was used with a Y coaxial to wire adapter to power the new 5" subs.(not powerful enough for good Bass)
The other RCA output was used for an Alpine PWE -S8 self powered sub woofer which I have under the rear seat armrest. Sorry, no more than 4 passengers.
Tried to insert some pics but can't for some reason.
Old 12-13-2018, 06:40 PM
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Other than a little detail and cleanup work I finished the installation of my Alpine CDE133BT and Alpine KTP445U. All speakers play as installed. though I am curious about the common ground. I found a common ground for the left rear speakers and I'm wondering if I should use it for the entire install?
The 3A fuse for radio illumination blew and I'll replace it with a 5A.
To be sure the door speakers are next.
Old 12-16-2018, 11:00 AM
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My Daimler/Majestic has the DBC2459 with the six speaker common ground. And that, as others have said, is the problem.
The second pic is the PCB from the radio (PCB P/N 099-7825-01), with the lamp module switched power wires (GR/BR, BR/WT) and the speaker ground (GR/BLK) connected to a relay to complete the circuit to ground (?).
The lamp control modules are switched power with glass tube fuses (pic 1). I used one as the switched power source for the radio.

Having removed this pcb from the radio I understand why the 3A fuse blew. I have no idea why Jaguar chose to control the lamp control modules through the radio (P/N 099-7825-01) and I will use a different switched power source?

Everything works with that 3A fuse replaced by a 25A fuse (head unit 10A, amp 15A). The wiring to the center fuse block (in the console) looks to be robust enough to handle the load. However, that circuit was designed to use a 3A fuse and not a 25A fuse. I'm in no particular hurry to complete my install. My goal is an electrically competent install. My current plan is to try to duplicate the circuit on the pcb using typical 30A relays for ground and a new switched power source for the head unit and amp.

Any thoughts? Any direction from electrical engineers

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