AFAIK, nothing in the convertible top sequence is linked to the engine start.

Long shot- the hydraulic roof draws on a 40A fuse, so maybe it’s shorting so pulling down battery charge, preventing the start.

 

Thanks Dave.

At this stage in the game I've been placing a "naked" relay in the starter relay slot so all I gotta do is go over and give it a pinch to turn the starter/engine over. I've got and have always had plenty of juice...

I am afraid to say (makes me crazy cuz she started at key turn alllllllllll this time) that either I'm over looking something pretty simple (some kind of confusion I've caused in the CAN starting sequence) or I have a problem deeeeeep inside the modules that are supposed to give the greenlight for start up...

In my XK8, more than once, I have hit and held the roof button while in gear, while moving (slowly) and the car would give a "restricted" message and once I think a gear box fault for raising or lowering the top in Neutral while moving. I've gotten terrible problems from ABS lights and brakes improperly bled. Had to shut the car off and right everything for those messages to go away for messing around with the top while in motion, before.

I have had problems where I would do something that seemed a million miles away from other systems that would end up effected... I'm never surprised by these cars and the things that pop up electrically.

I don't know definitely BUT I don't think, as a safety measure, it's not impossible for me to believr that there is something that has caused a hiccup in the starting sequence on these cars.

Once I heard someone pinched a wire screwing in a sun visor and the car went nutts...

But,,, and I have been before, I could be wrong.
​​​​​​​Anyways, I'm at a loss on this one

 

For those that are still with me, lol

Mertz hooked me up with this information long before I'd thought I would need it in a different thread... He must be a fortune teller... Starting on page 14...

Means more investigation,,, but its spot on giving a good road map!

 

BTW... This is what I found of the "Realgauge" system... I since resolder and replaced. Ashamed to show my soldering job but I think it's ok.

 

And then there's this. The dreaded P1638!!!
Mind you,,, the connector above.
Are things starting to make sense?
Wouldn't that be something, if !?!?!

Except for the 02 sensor DTC (and the dreaded P1638) I caused all the other faults...

 

Trying to solder that real gauge component,,, it's the size of a nickel, smaller than a quarter!!! I'm going to remove it ALL for now.

 

Never did get the (pg 15 of attachment) the dreaded P1260 code tho... I guess my problem, whatever is causing the p1638 and (I think) the Realgauge, wouldn't trigger the p1260? Now I'll have to wait until Saturday... CrazE maker!

 

Still not entirely clear if you get an engine start by manually operating the relay. I imagine that you don't?

 

No I don't sad to say. I'm sure I'm not getting normal spark or fueling (if fueling ever was "normal") conditions... I was "layed off" yesterday. Corona. So I will be back at it again today. Benefits of the Zombie Apocalypse.


​​​​​Something came back to life tho, it seems. I'll look back and look at some of the OBD screen shots, but I think this is the fist time I've seen the p1638 code describing a dead or faulty instrument cluster (IC)... From 2003 on, the IC plays an integral role in start up, and other things "passive security".

In other threads I've read where folks say when they get the p1638 code the car shuts down immediately and will not start. The p1260 describes a fault in the conversation (with sub faults when using a better code reader) between individual components of the start up challenges. From the key to the relay itself.

Let me try and repost the article (page 14) provided me by Mertz,,, the future teller.

 

No joy!

I've swapped out the exciter. No change
If I set the alarm and reach thru the window with key into the ignition and turn, alarm trips... Keying door shuts it off.

I'm checking relays and fault codes again. New one today. P0646 - something to do with the AC clutch...

I just don't know anymore. I need a computer and a cable hookup.

​​​​​

 

Looks like heat.
New KLM on the way with matching digits for 30 bucks...
Then,,, the Russian key programming dude...
See what he has to say.
I hate spending money for people to do my work.

But,,, good things happen. Roof works!!! Goes up and down with the button, and the key, bleed out nicely... Tricky getting the hoses right...

So,,, I'm into this thing for $200 or so, now.
Just can't start the doggone thing, lol. Yet!

Inside module case

KLM innerdz...

Cleaned up Neutral Switch

 

Well, what was the outcome?
Did you ever get it started?

 

I did... there were a few angles...
Where are you with yours?

 

Oh, I have no issues, knock on wood.
Sometimes posts can read like a good suspense novels. Had to know the ending. 😊

 

Hahaha... I wish I could claim, ending, ending...

It was/is a flood car and I'm amazed that the problem (and I'm sorry to everyone here about being so bad with following my threads thru tocompletion) is really the only problem that remains.

Yes, the key transponder module needed replacing, which meant a new key and some programming... Yes, there was a lot of digging into the function of the security system and BPM and more and the car STILL will not start with the key. Its basically (is anything basic with these machines) an issue to do with the 12v power from the trans module OR the ECU triggering a the starter by grounding the relay on command with key turn - either or both ain't right to this day. I have a 30yo Sears roebuck trigger on the passenger seat, car fires right up - she's purty...

I've been meaning to have a trans-Atlantic call with one of the guru's here to finally try and hammer out the problem... summer fun has gotten in the way...