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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.

WARNING!
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.

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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

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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

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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_2763

 

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

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

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Return Ferry car park

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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

board2

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

XJ6R – Transmission Wiring Damage

Transmission Wiring Damage

Another common failure, especially when removing/replacing the gearbox is damage to the cable loom. I had noticed the damage to my loom while moving the engine/transmission around the garage. There was at least one severed cable and a few more that were badly compressed which would lead to a failure late on. The first image shows the broken wire and if you look closely at the orange wires you can see a couple have been damaged too. I cut out the damaged area and inserted suitable replacement wires. The connections were solder jointed and then covered with heat shrink tubing to protect the joint. Finally I used some loom tape to protect the complete loom.

Damaged Loom
White & Slate wire cut through plus some damage to the Orange wires
Repaired Wires
Repaired Wires
Final protection with tape
Repaired loom – Final protection with tape

XJ6R – Rear Suspension

XJ6R – Rear Suspension

Life has been busy recently,  I have been on a couple of work trips, great trip to  Spitzingsee Lake in Schliersee, Germany not far from Munich for an EMEA team meeting. Great venue even if it only stopped raining on the last day.

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Sunny Day

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As per usual, DIY, Gardening and even the occasional trip to a car show took place and kept me out of the garage. I did snatch a few hours here and there. I had refitted the refurbished steering rack but a much longer task was running the fuel pipes over the rear suspension cage.

Rear Suspension Cage Drop

To run the fuel feed and return lines back into the spare wheel area in the boot I had to run a the fuel pipes over the rear suspension cage. This meant I had to drop the whole rear suspension cage. This is not too much of an issue as there are only eight bolts holding the four mounting bushes to the chassis and then the bolts holding on the rear trailing arms.  The full suspension cage is really, really heavy so if you need to do this please take extra care. I managed to lower it without incident and ran the two pipes over the top of the cage area exiting via an existing hole in the boot. I also took the chance to change one of the small trailing arm bushes whilst it was off as well. No drama so not really worth writing up specifically. During the refitting of the cage I discovered that one of the four Metalastic mounting bushes had come apart and needed changing. As I had four new bushes on a shelf I decided to change them all. I had refitted the suspension about 3 years ago and the car has not really moved since then so it was just time based deterioration of the bush as they were all OK when I last looked at them.

Changing the bushes is not that hard, just a little awkward to get to some of the nuts inside the cage. It is however a bit of a pig getting the holes lined up when reassembling things. My recommendation is to loosely fit the bushes to the cage, offer the cage up to the chassis and only tighten the bolts once you have managed to get the bolts that go through the chassis pushed all the way through and nuts screwed on. Trying to align the bolt holes through the chassis with the bushes firmly attached to the cage is not going to work! I am speaking from experience here so don’t waste the time trying to align it with jacks, using leverage and so on.

The failed bush is shown below with a little sideways pressure is applied. The faults are highlighted with the arrows. The light brown side has come away from the inverted “V” shape in the bracket. The right hand rubber has also come away from the outer bracket.

Rear Suspension Bush
Rear Suspension Bush

Its all reassembled now and back on its wheels.

Fuel Tanks

The twin tanks in the S1,S2 and S3 models are notorious for rusting away and leaking. I did have a spare tank in the garage. It came from an old Series 3 car that I had scrapped probably 15 years ago. The fuel tank had been stashed away waiting to go into the car to replace the rusty/bodged repaired ones that are currently in the car. The S3 tanks have the low fuel drain that I will need for the single external pump option I am going to go with. Unfortunately even though I stored this tank with the view to use it, on close inspection I discovered it does have some pin holes up at the top around the fuelling hole. The pipe assembly appears to be braised in place so no chance of just welding up the holes and I don’t have the facility to braise. I will probably just put some kind of epoxy or liquid metal over the area as a temporary fix whilst I find the funds to replace both tanks with new ones.  (approx £250 each)

Fitting this tank temporarily, running the outlet pipes into the boot area and searching for the switch-over valves are the next things on the TODO list.

XJ6R – Steering Rack

Steering rack

I decided to rebuild the steering rack whilst I had easy access to it with the engine out. The bushes were “cream crackered” as can be seen by the photos. I had some replacement Poly based bushes that came with a car I purchased years ago. The bushes are in fine condition so I used those. The old bushes were pushed out using a couple of sockets and a threaded bar to get it moving and eventually gently tapped out. The new ones were pushed back in and I am just awaiting delivery of the rack rebuild kit.

Knackered bushes
Knackered bushes

The first challenge was to identify the rack type. There are a few variations on steering racks over the years and it was not straight forward to identify the one straight away. I did a little searching on the internet and through the parts/service manuals and got the impression I had the Adwest manufactured part. A close look at the steering rack once it was cleaned up and on the bench revealed a few words and numbers cast into the rack. You can see these in the photos below:

HBD 12251
HBE 12251
HBD 12241
HBD 12241
HBD 12211
HBD 12211

I found the following identifiable words/numbers POW-A-RAK and three numbers HBE12251, HBE 12241 and HBE 12211. A little more searching on these and I found this page which lists the casting numbers as ADWEST CAST NO HBD12241- HBE12251- HB12211.

Also this site listed the parts as Adwest too.

JAGUAR 1973-79 XJ6/12 80 cm Short Pinion Series 2 & 3 Adwest HBD 12211, 12241, HBE 12251 & HBE 16400 P2318 NAK8076

Compare the pictures with those in the parts manual and the repair kit part number is AAU1503. I have ordered a repair kit and new bellows to finish off the job. As it happens I also have a spare steering rack from an older S2 XJ6 which is the Alder type so I should be able to rebuilt at least one of then regardless 🙂