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XJR6 – New Parts & Decisions

XJR6 – New Parts & Decisions

I have been working on getting the next stages of the project sorted and needed some more new bits. I have summarised them below:

  • Purchased and fitted a new Brake Master Cylinder & Reservoir from SNG Barratt
    • Pins for reservoir also ordered but the “R” clips were not available so ordered some elsewhere
  • I ordered a pair front shock absorbers (CAC9089B) checking they included the fittings on the top of the shock as some do not appear to come with them
  • I ordered a small alloy filler cap and tiny header tank for the inter-cooler system which I will keep separate from the main engine cooling system
  • About to order an XJS header tank as per Larry Louton used in his car on the Jaguar forum
  • Decided to use the XJR AC set up as much as possible so ordered a new condenser and receiver dryer
    • I will have to have a couple of pipes made up to match the newer XJR pipes with the old evaporator unit in the S2 dash. I have both the old and new pipes so maybe get them cut and joined?
  • Decided to go with a reconditioned S2 radiator I purchased a few years ago (unless I can find the original and it is in OK condition)
  • Came across the size issue with the electric fans as described below but will probably do something similar to Larrys solution as per the link above

The issue with the radiator & electric fans on the XJR is that they are too high to fit into the space in the Series 2 XJ6. This means I need to use either a Series 2 or series 3 radiator and causes a number of issues as follows:

  • There are gearbox cooling pipes that screw into the XJR radiator where as the older S2 radiator used a tube that fitted into the large radiator pipes with the gearbox fluid running inside a collar. I seem to have mislaid that tube/collar too so I will probably have to buy a new one and change the pipes to fit. It might be better to go for a horizontal alloy cooler that I could fit in the front somewhere. Try searching for “universal 7 row cooler” to get an idea of what I am thinking of.
  • I have two radiators to chose from. One is old and rusty looking and will no doubt require a re-core and one all painted gloss black. I do remember purchasing the “reconditioned” one a few years ago.  Neither of them have a fitting for a temperature sensor. This is a little confusing as I checked the older “tear down” pictures and I can clearly see a sensor in the lower right hand corner when looking from the engine bay at the radiator. I will have to hunt around and see if I can find the original radiator along with the gearbox cooler tube/collar.
    • Original radiator & sensor
      Original Radiator & Temp Sensor ~ middle
  • The XJR had electric fans so I need to have some form of electric fans on the new install. As you can see from the pictures below I have the original S2 fan shroud which is all tatty and rusty, A series 3 plastic surround which has the single fan cutout for the engine driven fan and the twin electric assembly from the XJR.
  • Original S2 fan shroud assembly
    Original S2 fan shroud assembly
    Rusty original fan shroud
    Rusty original fan shroud
    Rusty original fan shroud
    Rusty original fan shroud
    XJR dual electric fan assembly
    XJR dual electric fan assembly
    Spot the size issue :-)
    Spot the size issue 🙂

    I plan to cut down the dual electric fan assembly and place them horizontally across the engine bay. This will decrease the height. Currently, I have cut across the bottom right hand corner (where the two lighter coloured flaps are in the photo) so it fits in at an angle but it looks terrible!

Larrys aluminum sheet design (on the jag forum) looks better so I will do something similar. During the rebuild I fitted a new front cross member due to it being rotted away. This means I can drill new holes to mount the radiator a little further towards the front of the car. That will give me a vital couple of extra centimeters providing more clearance between the new fans and the belts at the front of the engine.

Fun and games 🙂

Thanks to Larry Loudon on the Jaguar forum for the ideas and inspiration

XJ6R – Air Bag Module “hard wired”

XJ6R – Air Bag Module “hard wired”

I have successfully wired the Airbag module into the car so it turns off the warning message and I can see the miles on the odometer. It will also stand a better chance of getting through an MOT now 🙂  I have drawn up the modifications if anyone else wants to do the same thing.

Hard wired for no airbags connected
Hard wired for no airbags connected

Please note that the pin-outs for the modules in the electronic guide do not match the actual pin-outs on the module. The groups of three pins and two pins are interchanged. The diagram above show the view of the solder side of the circuit board.

Previous article

Kempton Steam Museum

Kempton Steam Museum

Visted the Kempton Steam Museum today. It was as really fascinating visit. I had been to see the engine run before but just the sheer size of these steam engines is enough to keep my attention. The building is listed and so are the Triple-Expansion Steam Engines. These are huge 3 story high team engines that used to pump ~33 million gallons of water per day to north London (15 miles).  They did this for 57 years! The engines and the building have been restored by volunteers with some support from Thames Water (built a boiler house for them). Just an amazing achievement to get one of the engines running again. They are so huge and heavy, around 100 Tonnes, that they had to start warming the engine on Thursday for today’s run (Saturday)

They do guides tours, definitely recommended, tea/coffee and snacks (great value and good quality). Out side there is a Steam railway and a play area for kids. Today there was  bit of a car show, Jaguars from the Surrey Hants Border JEC Club (Thanks for the lift and company Neil) and a range of other classic cars plus a long row of American classic cars too.

Nice video of the engine starting on youtube.

Engine Number 6
Engine Number 6
Steam Turbine driven Water Pumps
Steam Turbine driven Water Pumps
Engine Number 6 running
Engine Number 6 running
Engine number 6 running
Engine number 6 running

kempton-steam-009 kempton-steam-008

These futuristic looking Glass Bulbs are actually AC to DC rectifiers (Diodes) They use Mercury as one contact and mains AC electricity is fed in whilst DC is the output. These are replacements and came from an Opera house of all places.

Mercury Rectifiers
Mercury Rectifiers
Mercury Rectifiers
Mercury Rectifiers

XJ6R – Air Bag Module Wiring

XJ6R – Air Bag Module Wiring

Following from the earlier success, I put the battery on charge which then limited further testing. The airbag module testing was complete however I had to make a choice. Modify the Air Bag Module (ABM) or build a circuit to fake the signal required. I decided that the quickest way to resolve the ABM output signal requirement was to hard wire the connections as if the airbags and impact sensors were connected. I will find a space for the ABM somewhere in the drivers side dash. Maybe to the right of the foot well just above the sill and under the air intake. I have put a second fuse box in that space on the passenger side.

I printed out the connector pin outs and drew the various links needed. This reminded me of having to do updates to circuit boards years ago but my eyesight was much better then! I still need to add the resistors to simulate the Airbags. There are no suitable resistors in my spares box so I will order some ASAP.

Air Bag Module and Pin outs
Air Bag Module and Pin outs

The blue wires are those I added to the module as drawn in above

Hardwired Links on Air Bag Module
Hardwired Links on Air Bag Module – click for a closeup


Loom requirements
Loom requirements

The loom is much simpler now. The original loom is used with the unused wires removed. Only one of the two plugs are needed now so I will use the empty plug to fill the open socket and seal the wire entries with some sealant or glue.

The following wires are needed:

  • Two ground connections that go into 1 after a few inches
  • Continuous +B power
  • Switched +B power (ignition switch position 1)
  • Air Bag module signal output

I just need to order the resistors to finish the job.

XJ6R – Major step forward!

XJ6R – Major step forward!

I have just turned the engine over using the original S2 ignition switch! That might not sound much but what it actually means is that the Security and Control Module, the Body Processor, the Exciter/Reader, the XJR key, the ECU and a few switches and relays have all agreed that it is OK to turn the engine over. The engine immobiliser circuit is accepting the new setup.

Overjoyed at this moment. Still a huge journey ahead but a major hurdle overcome.

I did paste a little update on the Jaguar forum but I will paste a full explanation later as I want to check out a few other things.

Later …

XJ6R – Airbag Module Output Signals Uncovered

Airbag Module Output Signals Uncovered

Following on from my previous post on the airbag warning message, I did some testing of the Air bag Module (ABM) today.  I identified the correct output signal that the Instrument panel expects following a “power on” of the ignition system. First, I used the original, yellow sheathed Airbag wiring loom and some resistors to fake the existence of Airbags. It turns out that the steering wheel Airbag reads approximately 1.2 ohms when in good condition.

Please be very careful when doing anything with “live” Airbags, they are dangerous hence I used resistors instead.
  Please, Please view any one of a number of videos available on the subject at the well known online video site prior to connecting anything electrical to an Airbag. If you do not know what you are doing, get someone who does. I  suggest you do not touch them at all. I have measured mine so you don’t have too. Just keep them locked away somewhere safe or dispose of them safely.  Do not come back to me of one goes off accidentally, you have been warned!

I did not have any 1.2R resistors. I ended up using four 6R resistors in parallel and just pushed them into the appropriate plug in the loom. It took a little debugging to stop the Airbag module from buzzing an error code. Once I had the rig working, I could see what the output signal should be in normal operation. The issue I had was that the Safing module does not have a separate wire for its ground connection. It relies on the connection to the chassis via the mounting bolts. As I had the module sitting on a wooden panel, I needed to provide it with a separate ground to get it working.

Airbag Module test rig
Airbag Module Test Rig

As expected, it turns out that although the circuit diagram says Ground and +B as the active/inactive conditions the reality is a little more complex than that.

  • With power permanently applied to the module the output signal is +B
  • Turn on the ignition power and the signal drops to ground for approximately 10 seconds
    • This is the Self test Pass signal “sequence” I was unaware of prior to this test
  • After that, the signal returns to +B and remains there unless an error is identified
  • I did try disconnecting the resistor packs (pretending to be the Airbags) one at a time and the signal goes from high to low as follows:
    • 3 times high to low
    • A short pause at high
    • Followed by either two or three high to low again depending on which “airbag” (actually a resistor pack) was disconnected
    • It then repeats the sequence again until the problem is resolved
    • This, I presume, equates to error codes 32 or 33 which is similar to the way the error code was displayed by the ABS module on my old XJS. It flashed the ABS light on the dashboard after you shorted a couple of pins together on the ABS module

The question is now, do I generate the same signals using just a few components or do I hard wire the required signals and use the Airbag module?

Debugging the Transmission MIL light

Having identified the requirements to resolve the AIRBAG warning on the digital display.  It was time to look into the Transmission MIL light issue. First there was the connection of the transmission loom to the transmission control module. I removed the panel below the gear leaver assembly which enabled me to push the transmission wiring connectors through a hole in the tunnel and connect up to the  transmission module.  The transmission error light was still taunting me! I did a slight tidy up of the wiring and re-connection of the Transmission module ground but still had the error. A little more debugging and discovered that I had not connected the permanent power feed to the transmission control module. I connected this up to the appropriate permanent feed, the MIL light went away.

Another problem resolved 😉

ABM Decision made

XJ6R – Airbag warning debugging

Airbag warning debugging

This post follows on from the last post where I explained the issue I was having when attempting to use the digital display from the XJR6. The display was showing the mileage then FLUID and AIRBAG messages. Having shorted the appropriate input to ground for the engine coolant sensor the FLUID message went away leaving me with the AIRBAG message to resolve. I tried shorting to ground or +B on the appropriate input but nothing seemed to clear the message. A photo of the Airbag circuit diagram is below, click for a larger version.

oldr 593

Since that time I have done a little more debugging. I proved that the feed to the main processor in the instrument circuit was receiving different signals depending on the status of the signal that should come from the Airbag Module. The Instrument display circuit, therefore appears to be receiving the appropriate signals to turn off the error message but it is not. The signals on the “Y” output of the HC151 chips looked like below with the signal grounded or at +B so you can see there is a difference and it was being propagated through the circuit board.

Signal with input high
Signal with input high
Signal with input low
Signal with input low (airbag failure light should be off)

A little more research showed that there is potentially an error message generated due to “No diagnostic module selftest Pass signal”. Does that mean that there is a short signal sequence that is emitted from the Airbag module after power on that the Instrument circuit is expecting? There is no clock signal synchronization between the two modules so it has to be pretty basic pattern. I suspect something like a high signal initially and then low for maybe a second or two in each state. I really don’t want to have to add the Airbag module into the car. Using a test rig is needed to see if I can work out the signal states for the Airbag module in normal operation. Hopefully a very simple workaround can be found other than actually adding yet another module into the car ;-(


Airbag error codes
Airbag error codes

The Airbag module has a single output signal (Airbag Failure Warning, connector AB1, pin 4). The manual states this is either ground or +B.  It does not have any other connections to the CAN bus or directly to any other module. The only connections are to the two impact sensors, the Safing sensor and the airbags themselves. Doing a little research, it appears that Airbags have a resistance of around 2-3 Ohms each. This should be replicated rather than actually connecting the Airbags to the module along with the potential safety implications! I still have the full Airbag system wiring loom along with one of the impact sensors and the Safing module. I will use this as the test setup and fake the actual airbag connections to identify what the “Selftest Pass” signal looks like.

This will dictate one of three possible outcomes:

  1.  Replaced the module by a very basic circuit to replicate the required initial signal(s) required to stop the error message
  2. I will fit the Airbag module in the car just to eradicate the error message and allow the use of the XJR6 digital milometer
  3. I will not use the digital display from the XJR6 to provide a milometer and use something else like a GPS based milometer instead.

Next post when I have solved it or given up!

Le Mans Classic 2016

Le Mans Classic 2016

I spent the last few days at the Le Mans Classic event. It is a great event and I actually prefer it over the real 24h race.

The journey really starts to get interesting as soon as you get near a ferry port or the channel tunnel. All sorts of classic cars on the roads eventually arriving and producing great views at the waiting areas to board.

IMG_2705 IMG_2704 IMG_2703

Then there is a quick look around on the ferry followed by the tedious crossing.

Stops for Fuel and the obligatory nature breaks on the way

IMG_2709 IMG_2708 IMG_2707

But once you are there things really get good!

Loved this Buick and Caravan
Loved this Buick and Caravan

Then just a mixture of pictures and short videos for your enjoyment

IMG_2731 IMG_2732

There was a brief flyby by a vintage fighter or two. This I think was a spitfire. The smoke traces it left behind had a life of their own!




IMG_2773 IMG_2777 IMG_2776 IMG_2775 IMG_2780 IMG_2779 IMG_2785 IMG_2784 IMG_2782 IMG_2791 IMG_2790 IMG_2788 IMG_2786

Loved these transporters all in fantastic condition

IMG_2796 IMG_2795 IMG_2794 IMG_2793 IMG_2792

Group C’s kept on their own – don’t know what happened to the Jaguar though 🙁

IMG_2801 IMG_2800 IMG_2799 IMG_2798 IMG_2797 IMG_2806 IMG_2805 IMG_2804 IMG_2803 IMG_2802 IMG_2807

Return Ferry car park

IMG_2828 IMG_2827

Amazing church in Dieppe. Went and had a quick look around it and one of the Volunteers was really knowledgeable. Kept us talking so much we were almost last to check in!

Amazing church


XJR6 – Electronics Debugging

Electronics Debugging

Having connected up the XJR dashboard display, I managed to get the Mileometer working showing the previous XJR milage. However it also displayed AIRBAG and FLUID repeatedly so not so good. The FLUID was straight forward to resolve by connecting the appropriate wire to ground. I misread the circuit diagram and thought the AIRBAG signal needed to be at +B. Having temporarily connected the wire to a +12V battery feed it still said AIRBAG. I tried grounding the wire, still AIRBAG! I tried adjusting the voltage to the wire using a variable resistance box but still same AIRBAG error. I took the display board out of the assembly and studied it closely.

Instrument Display Board
Instrument Display Board

I traced the input wire (pin 45) to an input on a surface mounted integrated chip with HC151 printed upon it. This is an 8:1 multiplexer chip. My guess is that the inputs are sequentially scanned and the outputs read to determine the status of the input signals. What that means is that if the chip is faulty (possibly damaged by me directly connecting 12V to the input?) then I cant just tie the outputs to one state as I will get other errors flagged as well. I am not sure this is the problem because the detail in the circuit diagram does say it is either ground or +B. The input circuit seems to have the signal going to the middle of a pair of resistors so the input voltage would be split in half anyway. The spec of the chip states 6V maximum input which is a little close, especially as my old XJS with an AJ16 engine used to run at 13.8V most of the time!

Pinouts from the manual
Pin outs from the manual


I have  ordered a replacement IC (or 5) just in case. They are not expensive but I will have to wait a few days for them to arrive. The suspect chip (11) is highlighted by the red arrow in the picture below.

Instrument Display Board
Instrument Display Board showing the suspected chip arrowed in red

The image below shows the location of the input signal, the +B and the ground points and the signal feed to pin 12 of IC 11


XJR6 – The engine is back in again

The Engine is back in again, hopefully finally this time 🙂

Firstly, sorry the site was down yesterday. Something wrong at the ISP.

I had a week off and managed to spend a day in the garage. I set things up ready to install the engine and just as I pushed the engine & hoist a few feet out of the garage to enable me to push it into the engine bay it started raining. Well obviously it was time for a tea break so I left it like that for about an hour and then proceeded to get the engine back in the car. It is now sitting on the engine mounts and the gear box is supported underneath with wooden blocks. I do have a slight problem now as I cant get under the car and into the pit without moving it and obviously can’t move it with the gearbox on blocks. I will have to support the rear of the engine to allow me to move it and carry on fitting the gearbox mounts in the new location.

Engine in place
Engine in place
Supercharged AJ16 engine waiting to be put into the Series 2
Supercharged AJ16 engine waiting to be put into the Series 2

The engine loom was pushed through the hole in the bulkhead as you can see below and then I did a little debugging of the electronics.

ECU plugs poking throught the hole
ECU plugs poking through the hole

I connected the power, checked for no smoke 🙂 and looked to see if the ODB2 port was working.

  • OBD2 wireless module powered up, app on iPhone could not see/connect to the ECU
  • Unplugged the ECU plugs and checked for 12V (+B) – not present
    • Checked the ECU power relay was switching on – it was not?
    • Checked the power in the new fuse box in the engine bay and discovered the relay in the fuse box enabling the “switched” power was not being energised
    • Followed the cables back because this was working a while ago and discovered the 48 pin connector I built into the bulkhead was not connected together fully.
    • Fuse box Relay was still not being engaged
    • Traced this back to the cable I was using for testing was not finally connected to the relay I wired up. The S2 ignition switch switches its outputs to +B when in each position. All the ignition switch positions on an XJR switch the associated output to ground. This means I need relays to convert the +B outputs to a ground signal to feed the appropriate signals to the various control units.
      • Wired up the correct cable to the relay output and now the Engine Bay fuse box is alive!
      • reconnected up the ECU plugs and now the ODB2 module/iPhone can talk to the ECU – hooray 🙂
      • Gave error code P1620 which looks like immobiliser error
      • Ok now I know the iPhone app will talk XJR I will purchase the full app and update you on further progress.

That was a good time to stop!

More investigations