Well, Spring is in the air...

Yesterday I wrote about squeaky belts. Only if this was all.

​Didn't drive much during the winter. Car sat for fairly long stretches. Battery is good (will take a charge on charger and be strong when done - holds charge well) AGM battery and fairly new. Car started up yesterday morning after 4weeks sitting. But cranked a little slow. Drove, Alt providing 14 v...

​​​​​Anyways, this morning I went to get in the car to go to work. Turned key and engine went to crank for a split second and then, clunk - DEAD. No lights on dash, no clicks from starter, just rock dead. Turned the key back and forth a few times, dead. Didn't even get that 2-3 second HVAC fan prime when cycling key. Door/puddle lights working, my little digital V meter connected to an dedicated B+ source showing 12v, just barely 12v. Usually it'll say 12.3 - 12.4....

Clicked the inertia switch up and down a few times. Water corruption maybe?

Could this all just be a weak battery?

Grant had an GREAT write up (as he does) for the ignition/key switch. Could this be that?
Main relay?
Bad earth somewhere?

Sorry for tying y'all up with such seemingly basic stuff these last two early driving season days.

 

I'd start with the easy stuff.

Have the battery tested.

Check battery cables for corrosion and fit. Are they tight? Same for the "+" junction posts on the firewall. And the main ground from battery to body.

Cheers
DD

 

This maybe?

 

Hi Jay

Could be the Fuseable Link on the Battery Positive Wire in the Boot/Trunk

That's the plastic red thingy that's Clamped on the Lead

Make sure its all pushed together Tight as this is the likely problem if you have just changed your Battery

No Crank No Start No Lights

 

Thanks Doug, OB...

I will check all you say just after work today. Beautiful weather here... Finally.

My key has always been sloppy. Really sloppy. I think I may also begin looking into the key gizmo if all else fails. I have a funny feeling that,,,, we'll see.

Tha is so much!

 

Jay,

If you're measuring just 12v whether on bulkhead terminals or direct in battery, I'd say that's where you start, not the ignition switch or anything else.

You need to know why you've only got 12v after running the car. You're either not charging the battery or you're losing it, or the battery can't hold it.

Start by measuring voltage direct on battery, then again on bulkead terminals.

Then start checking the connections on the battery posts. Then charge the battery to full, disconnect, measure voltage then measure sgain in 12 hrs. Then, if 12 5+v, start car and measure charging voltage at battery terminals.

Good luck

Paul

 

Hey Paul,,, and ALL 😊

Just got home, to the car, and strange stuff.

The battery terminals and all connections in the boot are good, tight and clean - it's hard to say that 100%, you know how it is, but all I can check quickly without spending a whole day seems right.

Of course the car didn't reproduce the issue when I got to it. Started right up as usual, starter spun strong. Then funny stuff started happening. But first I'll say with car running I took V readings at the battery 13.96v. at the posts under the hood 14.05 14.10 v. Disconnected the ground car running, car stayed running - my little volt meter shot up some from the usual 13.8 - 14.0, 14.1, 14.2 v to 14.6-7 v. Reconnected the ground at the battery back down to the usual 13.8-14.0 numbers.

I have a second dedicated ground off the alt to the body of the car. I need to get under the car to check the strap at some point and will...

But heres the thing - and this never happened before. If I touched the brake peddle I would a SHARP drop in voltage. The car would kinda hiccup and I could hear something like click (or something) in or under the dash. The IC volt meter would drop severely and the heater fans, which I had running (don't know why) would definitely hiccup. Then, the speedometer (which doesn't work actually) would kinda jump. RPMs would also react... Then, I'll touch the brake peddle and NO change... Do it 5 more times, fine, the 10th or 15th time, same strange behavior. Don't know what's going on.

I turned on the lights, this didn't reproduce the phenomenon. Blew the horn, turned in stereo, hazards, windows, nothing reproduced the THING. Just tapping the brakes. Strange.

Are there other things tied into the brake relay? System? Pump?.... I guess it time to take the electrical diagram dive 😖

 

BTW - this Mechanics Stethoscope is A.W.E.S.O.M.E!

 

Jay,

Just a thought, the application of the brake pedal with strange electrical things happening on an interval basis COULD be linked to the abs pump kicking in periodically as the accumulatir discharges. If that were then linked to an earth problem either at the bulkhead or instrument cluster, it might explain your symptoms.

Next time it happens, see if you can hear the abs pump kicking in.

Paul

 

Jagjagjay, NEVER disconnect the battery, car running. You can damage your alternator doing that. Some XJS have a load dump module which is supposed to prevent damage, but don't chance it.

Jon

 

Good Morning, Paul. Thanks.

I can't say that I've had the sense or noticed the "hiccup" connected to a KICK from the abs pump. I drove the car in this morning and still, when I hit the brake 1 out of 5 times, give or take, I get a reaction at the trip computer (dims and brightens) the speedometer (which has never worked) bounces up to 20mph then falls back, the tach - basically the instrument cluster gets a jolt. And who knows what else? Also, a thread I started a while back as first inquiries, my heater blower fans actually SPEED UP when I hit the brake pedal.

I am no good with electrical issues really but I'm getting some sort of back feed from the braking system, brake light system, to the OTHER things.

I don't know if this is or isn't connected to the flat rock fault that shut the entire dash, key and starter engagement the other day - but I better figure this out.

I can say that when I turn the key the speedometer jumps and will go up to 70-80mph (which I expect from the tach) as the starter spins - and then fall back as soon as the car starts.

I'm all sorts of puzzled and this needs to be cleaned up ASAP.

All sorts of open to ideas.

 

Thanks Jon. I did NOT know that - I don't need anymore troubles... Im pretty sure that I discontinued that module but I'm not sure... Thank you.

 

Without posting pictures of all common ground points what I just saw,,, learned I dare say,,, is that the instrument cluster, the brake light switch and the blower motors are all connected/grounded at G12 ground point BEHIND the AC system....? Basically low down in there behind the dash.

What would cause power to travel back up thru a ground system into these components - and is it logical to assume (and you know what they say about assumptions - multiplied by the fact that it's an electrical assumption) that it's source is the BRAKE, since the issue appears with applying the brake??? Ohhhhhhhhhhh, why why why, lol

 

So, I'm at work, windows down, public street, just went to turn the key - all's DEAD. No power in the car - anywhere. Going to be an interesting day...

 

Jay,

Feed back is a fickle thing at best, and finding the exact culprit is more by accident than plan.

My thoughts from afar.

+ve power issues. Check and clean ALL the battery cable points, battery (done as you stated), +ve post LH side in the engine bay on the firewall. +ve post in the engine bay, RH side firewall. This RH side post has the power feed TO the Alt, and starter motor, and sometimes other stuff.

EARTHS, mainly the engine strap/s, or run a BIG diameter dedicated cable, engine to chassis.

Instrument cluster earth path, crap from the factory, guess how good that be 30+ years later, oops.
Tail light cluster earth integrity, not good from new either.

There are some earth straps on the A Bank Inlet manifold, rearward. More on the radiator support panel, RH side.

FORGOT:
Battery disconnected when messing with any +ve connection. One stray spark and I would hear you from here.

That is step one, and usually cures the Gremlins.

The ignition switch electrical section, as you mentioned, is in dire need of a service, and may be another item causing this odd issue.

 

UPDATE: Seconds after writing that message I did what I usually do FIRST when working on electronics... I BANGED on the knee bolster with the key in the slot and in the on position... Low and behold, dash lit up, car started I rolled up my windows and went to work...

Just read your post Grant and I'll be getting into what you're describing and taking you hints and warnings. Will also be taking out and servicing the ignition switch assembly...

So,,, BANGING on it??? Ain't that sumpthin!?

 

Want to see/hear how a desperate Man on the side of the road in NYC freaks out when an XJS finally DIES, lol... Well, needs some CPR, lol

So I got in the car after work. Things were testy from the outset. Everytime I hit the brake, car would hiccup and eventually died... Heres what I did. Pulled over, dropped the knee bolster on the LH side. Reached in and started jiggling wires with key in the ON position. Nothing.

Reached in DEEPER, convinced it was a relay (brake light relay or something connected) and the back of my hand HIT something and the dash lit up. Kept giggling... Finally found the offending harness...

In the 1990 is this pair of WAY too big connectors under the steering column. One of them brings battery voltage into the ignition switch (they do a few things apparently) then back out depending on key position to the second giant connector and between the two of them they are the initial electrical distribution points sending lightning to various (and this is all kinda speculation-ish) to different systems in the car, bringing systems to life. Providing power to many areas for right running and operation.

Sure enough the connector, one of the two, had failed. I saw a thread the other day where someone had discovered that the male to female connection point INSIDE the connector had failed internally. Same here. I cut the one (main heavy brown wire) that seemed to be causing all the grief when I went thru and carefully touched or jiggled wire by wire,,, then, I connected it directly. EVERYTHING went back to "normal"...

And get this. Volt meter on dash went higher than I've ever seen it, heater fans stopped pulsing on pressing the brake pedal and stopped pulsing in time with the blinkers,,, AND THE CAR RAN BETTER... I'll be DIPPED in MOLASSES and DUMPED on a FIRE ANT hill, lol... OMG these cars...

GRANT, we gots ta talk...! So, me being me, never satisfied with good enough, I removed the ignition switch when I got home and figured I'll just do the Grant Francis ignition fix thing while I'm in here... I opened the thing and SIX springs popped out,,,, 4 more tweezer worthy parts and,,, a GD BALL BEARING...

I almost busted out the phone so I could buy a ticket to Australia, track em down and GIT em, lol... Good ol GF! Making it sound all easy! I'll save how the ignition switch adventure went for another day? GF!!! Imma git ya!

So, cars back running, all back together.
Nuther XJS adventure...

Thank you all for your never ending help, guidance, support and the feeling that something is right in the world, everytime I tune in here 😊

Innerdz of the ignition switch

2 giant connectors under stearing column on the side O the road. Connecting brown wire made things better than they've ever been.

Offending pin(s) in plug... Actually, I believe it was the female side gone wrong.

A few of the springs bits and pieces inside the ignition switch. Bad photo, but I was so nervous I couldn't take pictures. New ones ain't cheap!

 

Terrific find and fix, JJJ. Well done you. When I did my rebuild and had the dash out and cleaned up evry single connector, earth, etc etc, it was noticeable how much sharper the electrical system worked. I take it you insulated that twisted together join though!

 

Thanks Greg... I did, I did... Bubble gum and a shoe lace...at the time

On the spot I used a short section of black tape that I pirated from another loom, left the bolster off and the under cover of the steering column and what not. Started to try and tidy up when I got to the safety of my street... When I got home is when I decided I would pull apart and clean out the ignition switch. What a thing. Give me hammers, crow bars and wrenches any day. Suddenly I found a need for good lighting, tweezers and fairly clean work surfaces. Under the dash, I have to go back in and clean things up.

Of course the ignition switch came APART ok (I can take things apart like a true professional, lol) but putting it back together, another story. I did get it though. BUT (and there's that famous word) the plastic was brittle and I did some damage to the casing. I CANNOT afford another right now so I will have to go back tonight after work and figure out a way to make sure that the front and back half's do NOT come apart - which would usually happen somewhere on the highway in Virginia. I don't want that. Epoxy? Some small zip ties strategically placed. The spring pressure INSIDE the device that pushes the arm against the contacts (pushing the two halves away from one another lightly) isn't so great, it's that circular spring, last stage of ignition/starter engagement signaling the starter relay, that puts a lot of stress on the body of the device in a rotational direction. Anyways. If anyone has any suggestions about how to SURE that up, I would be greatly appreciative.

In one of the photos I think you can see a 6 way connector supplied by Brads disassembly of his HE XJS. Same gauge wires where it matters BUT, that connector is itself as old as the one I would be replacing. Different design, more robust, but as old. Still, the OE stuff from Jaguar, even though 30yrs old, is still more robust than most aftermarket stuff. I have some decisions to make and am all ears.

Gotta run into work now. Good day all. I'll be back to this

And Doug!!! The brake PADS made a great difference. I'll post back to that thread as well ASAP...

 

Hi Jay

Well done! you may even have to show me how to do this one day!

Meantime why not try Hot Melt Glue that can be cut through with a Craft Knife if you need to get it apart at any time

Well done again!

Alex