Greetings —


I am a longtime classic Jaguar enthusiast but a “modern” Jaguar newbie-ish.

My wife (!) recently found and purchased a magnificent 2001 XJ*R*(!). We both adore it.

Last week, after roughly 45 days of ownership, the battery went dead (we both thought she had left the parking lights on). I charged the battery and all was well until the car sat for three-ish days, after which time the battery was dead again.

Hoping to eliminate the three-ish year old, Brand-X battery as a cause, I purchased a new, German-made battery and installed it on an extraordinarily quiet Sunday morning (we live out in the country so it was **very** quiet). Upon hooking up the battery, I heard a faint whirring noise in the trunk. It turns out that it was a device sitting behind the trunk liner on top of the navigation DVD drive. While most sellers on eBay treat it as a navigation component (and it may have some navigation functions) I’m pretty sure it’s LNF4170AA, an audio amplifier.

We drove the car all over on Sunday and periodically checked to see if the whirring continued, which it consistently did. I did not have a chance to work on the car during to day and was too tired to work on it Sunday night but went ahead and disconnected the battery cable. Upon so doing, there was a faint “pop” of the kind that older guys like me will recognize as an audio amplifier being turned on or off, the sound coming from the speakers connected to the amp.

This morning I removed the trunk liner and disconnected the amp. The fan turned off. I plugged it back in and the fan stayed off. I let it sit for roughly an hour and now the fan is back on.

I think the amplifier is not turning “off” (and, given the “pop,” I think it’s the entire amplifier, not just the cooling fan on the amp). While I am tempted to buy one on eBay, if the problem is, say, a stuck relay, that will not solve the problem. This “modern” Jaguar has THREE BLOODY FUSE BOXES and is terribly complex (my E-Type daily driver has done just fine with TEN FUSES for nearly a half century, bah, humbug).

In short, I don’t even know where to begin. I have done various on-line searches to no avail.

Has anybody else experienced a problem of this nature?

Regards,


— Kevin (’69 E-Type, ’01 XJR, ’01 S-Type, ’03 S-Type NAS 5-speed manual, lots of others in the past)

 

I have not experienced this, but it sounds like the heat sink sensor for the fan is faulty and causing your issue.

 

 

Thank you for the responses. I think that this is a sufficiently "weird" situation that nobody has had it happen before.

I am going to start a new threat wherein I seek information about how the audio system works (that is, really, how power is switched and routed) so I can divine a repair or solution (such as adding my own logic circuit -- a crude one with relay, perhaps triggered by the antenna, which is working properly).

-- Kevin

 

Here ya go...http://www.jagrepair.com/images/Auto.../jagxj1998.pdf
Taken from... JagRepair.com - Jaguar Repair Information Resource ...you'll want to Favorite this.

 

I would be very surprised if there were any moving parts in that factory amp. Are you sure it's not the nav DVD drive making the noise?

 

The DVD drive did whir, etc., etc. HOWEVER, it is very clearly the fan on the amplifier that is running intermittently. I have started a new thread to address that gremlin.

 

Kevin, I have a 2000 XJR with the same issue I'm trying to sort out. Instead of starting a new thread about the same (potential) cause, I will respond here.

The battery will drain completely after about 3 days. I suspected the audio system fuse (#12, I believe) which is a 30 amp fuse in the fuse/relay box by the battery. When I install the fuse, the cd changer will cycle through each of the 6 decks. It's not quiet enough in my parts to hear any whirring sound, but something is going on. After leaving the fuse out, I did not experience the battery drain issue. Reinstalling it caused the issue. Yesterday I purchased a multimeter to confirm my suspicion and rule out any other drain causes. With the battery disconnected and multimeter connected, open doors and boot lid latched manually, the multimeter set to 10A would read mid-2 amp range when the multimeter leads were touching the negative battery post and the disconnected grounding pigtail. It would quickly drop to .44 amps, then slowly trickle down to .04 (fluctuating between .03 and .04) after about 15 minutes. There it would stay. When I inserted the 30 amp audio system fuse, it sparked a little as it began to draw in the 2.5 amp range and cycle the cd changer. Then, it settled down to drawing .88 amps thereafter. Even after an hour it was pulling .88 amps. So somewhere in the audio system is my gremlin and I suspect the amplifier. Next, I have to pull out the trunk lining and start disconnecting components to find which one is the issue. Of course, like you, I don't know how to ensure that buying a used amplifier or cd changer on ebay or elsewhere won't have the same issue.

-Kent

 

Kent --

 

Update...

I pulled the carpet cover to reveal the cd changer and amplifier. With the multimeter attached and all systems "asleep," the draw was -0.04 (fluctuating between -0.03 and -0.04). Reinstalling the 30 amp audio fuse, the cd cycled through all 6 decks and I saw the cooling fan on the amplifier running. The multimeter reflected around -1.50 amps drawing. After the cd cycled and settled down, the fan on the amplifier was still running, but the draw was around -0.90 (fluctuating between -0.89 and -0.90). This continued for about 15 minutes. I pulled both block plugs on the right side of the amplifier and there was a blip on the multimeter, but no change in draw. When I pulled the round black plug that feeds to the head unit, the multimeter went to -0.04 and the amplifier cooling fan went off. By deduction/process of elimination, the issue is inside the car...seemingly. But the draw traverses two head units. The draw started before my original head unit died. I replaced the head unit with a used one that works perfectly, but I still have the draw. I don't have a wiring diagram, so I don't know if the amplifier is powered by the head unit (via the black wire with the round plug that plugs into the side of the amp) or if the head unit is powered by the amplifier. Don't know if 1998 and 2000/01 XJ8/XJR wiring diagrams are the same, but I'll review the wiring pdf that Highhorse posted for a 1998. But, clearly, when I disconnect the round black plug from the side of the amp that leads to the wiring harness into the cabin, the major draw stops, as does the cooling fan on the amp. Perhaps someone can chime in on this; from where the power originates for the head unit and amplifier.

With any luck my and Kevin's issues are the same, so I'll continue to futz around with mine and report my findings.

-Kent

 

Kent --

 

Kevin,

thanks for the info.

 

May not be the reason in the case of the amplifier being powered-up all the time but just to share my experience with high battery drain.

In my case (Daimler Super V8), one day I found the battery pretty well drained after the car was sitting for about three days. Then I heard a faint whirring sound from the front of the car. When I opened the bonnet, I could hear that the supercharger pump was running and the throttle body was buzzing even though the ignition was off. Looked at the diagrams to identify which relays are relevant and found that these relays (two I think, cannot remember exactly) were energised. Disconnected and reconnected the battery but the relays came on again and the pump and TB started running again. After a few hours looking further through the diagrams, I could see that the mentioned relays are on the same line which goes to the alarm siren. When I disconnected the siren, everything came back to normal. Obviously, something went wrong in the alarm siren and the current from its battery was flowing back into the wiring grid energising the relays which run the SC pump and the TB. Perhaps worth checking whether it is perhaps the alarm siren (its battery) causing the issue with amplifier powered-up all the time.