Hi guys,

I have some problems with a 1995 XJR6 in U.K (Cheshire).
ECU was rusted and had some ‘additional’ wiring to get round renewing broken pins which I have had professionally rebuilt.
I assumed this was my no crank problem but alas, it prevails.
I have a fully charged, nearly new battery that throws a 4.0l X308 over no problem and power to both front fuse boxes.
All lights and wipers work, display illuminated properly BUT Check Engine light goes out with the others.
I have a bleeping and ER on the air con/temp display which goes if I use the blower displaying the desired temp as it would normally.
Ive read through a few threads regarding no crank issues to no avail.
Electrics is my weakest point so idiots guide of any help would be appreciated.
I have a red light in the P position and clicking when moved left to right. No movement of the gearstick makes a difference (I have not moved any switches in the gear selector area).
I have tried a spare BPM from. 4.0l Sovereign of the same number (BB suffix instead of AA) which did nothing.
From the below, stolen from another thread, I checked pin 20 on the black connector showed 0.75v with ignition in position ll and pin 33 on the yellow which showed 12v.
Does this (pin 20) point to the Park/Neutral switch failure?

“McScrabble,

I would look at the BPM to give you an indication of where the problem may lie.

First check pin 20 of the black 48 way connector. You should have 12+v there and then when you turn the ignition to position III, the signal should go to ground. If it does then the Park/Neutral switch is operating correctly

Then check pin 33 of the yellow 48 way connector. You should also see 12+v here with the ignition off and ground when switched to pos III. If you do have a ground signal then all is working well. I would then suspect the rotary switch, the starter relay or the starter itself. Follow the circuit below and you will find the culprit.”

As an aside, the car has some rust issues so should I be looking for groundings? If so where exactly?

Thanks for any help.
Rob

 

By black and yellow connectors are you at the BPM connectors ?

FC2 - 20 is " seeking " a ground

FC1 - 33 the BPM " provides " a ground to close the starter solenoid relay

Position III of the ignition switch is pin 1 to pin 5 and is a momentary contact so it's not a solid meter reading

The following statement is correct except you have the GM transmission on the SC engine so you use the linier switch

rectangle box in the picture to the right of your gear selector and the small not in park switch with the pigtail on it

Also pin 20 should see a ground with the gear selected to park or neutral , the ignition key is a seperate wire on pin 41

I would look at the BPM to give you an indication of where the problem may lie.

First check pin 20 of the black 48 way connector. You should have 12+v there and then when you turn the ignition to position III, the signal should go to ground. If it does then the Park/Neutral switch is operating correctly

Then check pin 33 of the yellow 48 way connector. You should also see 12+v here with the ignition off and ground when switched to pos III. If you do have a ground signal then all is working well. I would then suspect the rotary switch, the starter relay or the starter itself. Follow the circuit below and you will find the culprit.”

Fuses .........

# 5 / 10 amp trunk fuse box , this fuse is hot at all times and the wire runs through the large BT4 connector pin # 47 ( brown / black ) wire above the fuel tank

This is a troublesome connector to reconnect so care must be taken to not break lock pins




# 2 / 5 amp RH heelboard fuse box , hot at all times

# 12 / 10 amp RH engine bay fuse box , this fuse relies on the ignition positive relay to close , does this relay click with key rotation

The relay is the one attached to the fuse box and a switching option is the one on the left engine bay fuse box

The white / pink wire passes through the Papa Indy 1 connector that can get corroded



Editing , wifi keeps dying

 

You're CEL Light going off with the other lights is the key pointer to your problem. This needs to remain on. Using a part of @Parker 2 diagram, this is the circuit you need to focus on. There could be other stuff also, but until you sort this out then you can't check anything else.





So, the flow of the circuit is
- a data connection from the Security module to the ECU to confirm security is OK (coming in on PI 105-35 in the diagram above)
- ECU then provides a Ground (out on PI 104-20) to the BCM (FC2-7) - to confirm cranking enable, and also to the Check Engine Light on the dash.

Problem could be
1. Vehicle is immobilised so Security module not providing the right signal (can't test this without specialist equipment)
2. Security module is dead so not providing signal
3. ECU is receiving correct signal but not providing the output to BCM and CEL
4. Cabling and/or connector damage between any of the above.


What's the history of the car. It is known that Security modules can die on cars that are laid up for long periods and then brought back to life.

Suggest you initially test the output from the ECU (PI 104-20). If you're not getting a ground on that pin then it won't crank (likely security issue if you are confident in the ECU rebuild). You should be able to jump a ground connection to this pin to help in diagnosing. If you do and it cranks, you're very close to the issue. (But if the issue is immobiliser/security it won't start as fueling is inhibited).

There is a function in Jaguar Diagnostics (IDS) that can override the Immobiliser (function is called One Shot fueling) to start an immobilised vehicle.

 

This is for Robbird10 for his clarity

A note on B1mcp's note with the pin PI 104 - 20 is that it is a discreate signal and not a digital serial like on pin PI 105 - 35 in the picture

This signal to pin PI 104 - 20 passes through connector Papa Indy 63 which is opposite left side of the engine block under the air filter

Light green / black wire position # 9

Same corrosion issues as the Papa Indy 1 and 61 on the right side

The more sensitive digital signal at pin PI 105 - 35 passes through the Papa Indy 1 connector at pin # 2 green / black wire

 

Thank you for the response.

Yes I’m at the BPM connectors.

Ive checked every fuse in the car and all sound.
Will look at the inputs/fuses/relays you suggest and the Papa Indy 1 connector.

Thank you

 

Thank you for the reply, much appreciated.

Car history is that its been dry stored and hasn’t run for some years, so that may tie in with the security module issue.
Will look at the PI104 20 and try to jump it 🤔.
I’m 100% confident in the ECU rebuild, Avilec on the Isle of Wight, professional outfit who did a great job on an XK8 ECU.

If it is the issue, I will see if my parts cars has the same security module, as it looks like they are interchangeable.

Many thanks for your time and help.

 

Be aware that the Security module is programmed to the keys, so you will need to overcome that if you swap modules.

It can be reprogrammed, or you could swap the ignition lock from parts car also, or the chip inside the module that holds the key data can be swapped.

 

Gréât thanks again for the advice.

 

Well, having gone through 90% of your very well explained advisories over the whole morning.....and after fumbling around with the ignition wiring as I was at a complete loss, I find, what turns out to be, cut out switch wiring tucked up under the steering column. Previous owner omitted, or didn’t know, to tell me🙄.
connected the dangling wires and boom, off she went.
(Took me back to my Mkll Capri days &#128514.
Attached it to a switch and the beast lives.
Apologies for wasting your time and many thanks for the help.
However, I’ve come to know the ol’ girl a lot better over the last few days. Had to get into crevices I have not needed to in my other X300’s 😉 so not a waste for me.
There’s a hefty screeching and smoking on one of the pulleys at the front of the engine but that’s for another day.

Thank you again for your time guys.

 

https://www.jaguarforums.com/forum/x...-crank-245339/

You can remove the right belt but you won't have A / C

But before removing belt paint a strip on the harmonic balancer pullies to see if they stay together as you load the engine pullleys down with the compressor engaged plus a high electrical load

There is a common Gates # for the idler pully

 

Thanks Parker2, much appreciated.