After decades of working on cars and flying airplanes I accept that rarely are simultaneous malfunctions unrelated.

After pulling the instrument cluster to replace to background bulbs, and the steering column to replace the tilt and reach motors, I have three simultaneous malfunctions that do in fact seem unrelated.

1. The green LED in the dash that lights up whenever our lights are on, doesn't.
2. The Passenger seat heater doesn't work.
3. The "Passenger Door Open" warning is stuck on.

Now, admittedly the car does have a few miles on her, so the door microswitch might be needing a swap, and that actually could be coincidental, but the other two failures are complete mysteries.

The green lite is an LED soldered to the instrument circuit board - what are the odds that it would fail (ever).

As for the seat heater, even the red light in the switch doesn't illuminate. Deadski

OK gang, ... have at it. What unicorn gremlin has beset me "this" time? - lol

Thanks all. You guys are great.

 

OK. Lets start by taking your coincidence down to two items.

The green dash light for the headlights is actually a tiny bulb in a socket on the front or the instrument cluster circuit board. It is not an LED and it is not soldered. You need to remove the instrument cluster circuit board to get access to it. It is an 'E73' subminiature wedge bulb.

These bulbs sometimes fail after the instrument cluster is removed and turned over, probably because because the filament moves after many years of sitting in the same position.

 

Hi White. I looked into the cluster. the high-beam was a replaceable bulb from the outside, but inside the cluster (on the front side of the circuit card) were what looked an awful lot like LEDs. Now, to be honest, I wasn't in the mood to disconnect all the ribbon cables. All I could do was lift the board up about 1/2" and peek inside.

Are you saying that if I remove the front panel of the cluster instead, I'll find the replaceable bulb(s)?

Thanks! - Jim

 

As for the other issues, the BPM, in particular fuse#5 in the driver side dashboard end fusebox has ties to the tilt motor, the seat heater switch and the door sensing. I would check that fuse first.

 

Yes, guarantee if you remove the ribbon cable and take out the board there is a replaceable bulb there. See the two front replaceable bulbs on the right.

 

Interesting. I believe our boards have some subtle differences. But I'm going to buy the bulbs tomorrow and pull the cluster tomorrow night. Are E73s common in the parts stores?

Thank you.

 

Hey White! You're in Arlington? Do you ever hit any of the car get-togethers in the area? I'm down at NAS Pax River.

OK, .... Yes - I've hijacked my own thread - lol

 

Yes, I try to get to most of forum get-togethers. Hope to see you there this year.

Auto parts stores should have it. It may be marked just '73' or '73LL'

 

Sounds good. I'd love to go over your car.

E73 / 73LL? I can't find that, but I have found 37LL bulbs. Typo? I'll check back tomorrow. Ciao!

 

Sylvania/Auto Trans Indicator Mini Bulb 73LL - Read Reviews on Sylvania #73LL

 

Be really gentle handling the circuit board. Also wear cotton clothing (cotton builds up minimal static) and discharge the static electricity in your body to a ground such as a water faucet before handing the board. Also handle the board by the edges. Particularly on dry winter days, these boards can be damaged by static electricity.

 

Good points. I actually have some background with ESD. Now, I wonder where my grounding wristbands are? (last worn 28 years ago! - lol).


I must have been getting goofy last night - I swear, nothing came up for 73LL. Now I've got it. Hope there available locally.


Any tricks/precautions to keep in mind for releasing the ribbon cables?

 

Scardini, dont know if you replaced the bulb or not but here's a difference perspective. When my headlight indicator went out last month i gave it a try without it for a few days. Turns out i like ot better off.

This is one of the only lights that doesn't dim withe the dimmer on my car. I found I love that it no longer glares at me on really dark night drives. Decided to leave it as is. No related issues so all is well without it.
.

 

Probably not Fuse 5. The door was sensed closed yesterday for one run (light out, and door locks working); now it's stuck "open" again. And I believe, if Fuse 5 blew I'd lose a ton of other stuff that's otherwise been A-OK the whole time.

Fuse 15 in the Pax Fuse box is also a possibility: it powers the Pax Door Control Module. But I think I would have also lost my window functions.

I'll check them both though - just in case. Excellent help Steve. Thanks a ton. Keep it coming.

It just may be that all three malfunctions "are" unrelated, but I'm programmed to search for a common cause before jumping down multiple Rabbit-Holes simultaneously. I've witnessed that scenario in action (IN FLIGHT). It took a while to get the other guy to ........ STOP, ... SIT ON YOUR HANDS, ... AND SHUT UP!!! Sure enough - there was a common cause. I don't know what he'd done if he was solo (cringe).

 

Ya know, John, .... I've got the 73LL bulbs in hand, but I'm starting to wonder about the same thing. That light kinda reminds me of the idiot cars that not only have a cruise control "engaged" light, but also a cruise control "on" light. Which of course, is ALWAYS lit. I can change the 73 anytime I want. Like you, I may give it a while.

 

The fuses check out, so I'll wait until the new micro switches get here and then some "Porta Chirurgia". (Door Surgery). Man how I hate having that red light lit.

Steve, I've also WD40'd the latch and exercised it a bit. No response. I wonder why, out of the blue, it started working for a while a few days ago?

As always - Thanks to all responders.

 

The weirdness continues. The pax door just closed itself on the way to Florida. Could still be the switch.

That leaves the recalcitrant pax seat heater as the remaining mystery. More fuse research is on the docket for next week.

Such fun!

 

on pax heater, if the seat moves then either the signal is not being sent from the push button in the dash or the seat module went bad..Try swapping modules the heater lines are in the 16 wire connector

 

Thanks Steve. Where are the 16 pin connectors located.

PAX door update: It opened and closed itself 2 more times during the 700+ mile trip. Gotta be the switch. I have two on the way. Oh goodie - - "another" skill - lol.

 

The seat modules are under the seats, The driver side usually has three connectors and the pax side two. The driver side will have three if you have memory seats. Just swap modules and plug in the 16 wire connector in its position and the 10 wire connector in its position and see if the driver seat heats up. If it does then the pax module is fine, if not then it is faulty.

If pax module is fine, then fault is in body processor module or the heat switch on dash. The body processor module is under the dash behind the area of the glove compartment. I have never had to find it.

So let's work on dash switch. Do you know how to remove all the facia and lower console pieces to get to the switch?
Jaguar XK8 Traction Control Seat Heaters Fog Lights Flashers Console Switch | eBay

Even if the pax heat light came on, that is a separate line than the switch line to activate the heater. The switch acts to ground. You could remove the switch module, disconnect connector and connect ohmmeter to pins 7 and 16 and push driver switch to see if you get a closed circuit and pins 14 and 16 for pax switch. You should get a closed circuit on driver pins, if yes, then you can test the pax side. If no closed circuit on driver pins, then I will need to rethink. If pax side functions and you get a closed circuit. I would then suspect the body processor module is at fault, presuming all connectors to all parts are clean and functioning.

send me your email and I can send you the wiring guide so you can look at diagrams yourself on computer, because this pdf is not readable.