Fitting a new TCU/F1 Gearbox Control unit question

[James]

I have a small issue on my 4200 CC, where the F1 pump does not prime when the car is unlocked (whereas it previously did!).

We have hopefully traced the source of this problem to the Transmission Control Unit (TCU) which is not sending the signal to the F1 pump to prime (whirring sound on unlocking the car).

While it seems fairly easy to replace the TCU, getting access by removing the battery, my question is; does a new TCU need to be programmed or setup to work with my car, or does it come ready to plug in and just work (so you just remove the old and replace with the new?).
I read mentions about software updates for different versions (year) but don't know where the software update would be installed.

Thank you, any thoughts most welcome.
James

 

[voicey]

It absolutely needs to be programmed - it will need to learn the positions of each gear in order to prevent it lunching the box and you will need to adjust the PIS properly to prevent it from toasting the clutch/flywheel. Oh and you'll need the old wear index transferred over otherwise you wont be able to keep an eye on clutch wear.

 

[CraigWaterman11]

James, I just want to make sure I kind of understand your line of thought on the issue your having. So are you stating the F1 pump is not priming at all? So you put the key in the ignition, pull both paddles back and it doesn't go into neutral (or any gear for that matter)?

Here's why I am asking. There's a pressure switch on the valve body that tells the NCR (TCU) to prime when it falls lower than 580 psi (hold on 40 bar for you guys), once that pressure is obtained, it tells the NCR the pressure is low, it primes it back to 50 bar. However, if you have good leakage rates, and accumulator the car does not need to prime every time you open the door.

Thus, we might need a couple more details. Can you clarify what you have done, and why you think it's definitively the NCR (TCU), not the pressure switch or the F1 pump, if the answers to my question above is it won't go into gear at all (or change gears).

{Aldous covered everything else if you find it is the NCR}

 

[maverick]

Hi James , you will need to program the new one to your car setup , basically some one will read you current settings and than transform them to the replacement unit . Voicey is your man and lives in London , he does all my diagnostics , top bloke . I also have a spare tcu which came out of my car when I replaced it with the original soft ware version . It's been rattleling around in my boot for the last year so not to sure if it's still ok but your more than welcome to try it and if it works and if you want it we can come to arrangement of cost . I think the going price is around £300 to £500 on eBay for a second hand one .

 

[James]

Voicey/Maverick, thank you this is very helpful and makes this a far more complicated job than I had understood. Voicey I would love to pick your brain and see how I best resolve this minor but annoying issue!

Craig, Thank you also, let me explain a little more to answer your question.
The car changes gear and runs well, I have no gear change issue at all. The challenge is that when the car is cold, you have to wait 5-8 seconds before it will start, either with the ignition on, or the key trying to start the engine, waiting to the F1 pump to fully charge. (and it does go into neutral when the ignition is on and you pull back both paddles) Also when the car is warm or recently used, it starts immediately.

I have just had the car serviced with Meridien Moderna, having previously noticed the lack of F1 pump noise after unlocking the car, I asked them to investigate the possible cause. They found that when the car is unlocked or the door opened, a signal was being sent to the TCU, but no instruction/signal was going from the TCU to the F1 pump to start the priming. So to verify this they were able to changed the TCU and then the car DID prime, when unlocked (from cold) so they suspect the TCU is faulty. (The F1 pump and relay were changed 18 months ago).

I had the impression this was a quick replacement of the TCU, (rather like the F1 pump relay) but it is clearly not.

This forum is such a wealth of useful information, thank you.

 

[CraigWaterman11]

Voicey/Maverick, thank you this is very helpful and makes this a far more complicated job than I had understood. Voicey I would love to pick your brain and see how I best resolve this minor but annoying issue!

Craig, Thank you also, let me explain a little more to answer your question.
The car changes gear and runs well, I have no gear change issue at all. The challenge is that when the car is cold, you have to wait 5-8 seconds before it will start, either with the ignition on, or the key trying to start the engine, waiting to the F1 pump to fully charge. (and it does go into neutral when the ignition is on and you pull back both paddles) Also when the car is warm or recently used, it starts immediately.

I have just had the car serviced with Meridien Moderna, having previously noticed the lack of F1 pump noise after unlocking the car, I asked them to investigate the possible cause. They found that when the car is unlocked or the door opened, a signal was being sent to the TCU, but no instruction/signal was going from the TCU to the F1 pump to start the priming. So to verify this they were able to changed the TCU and then the car DID prime, when unlocked (from cold) so they suspect the TCU is faulty. (The F1 pump and relay were changed 18 months ago).

I had the impression this was a quick replacement of the TCU, (rather like the F1 pump relay) but it is clearly not.

This forum is such a wealth of useful information, thank you.

So the NCR will tell the car to prime, based on the sensory information, when you have the key in the ignition, or driving the car, but not when you unlock the door/open the door? They verified that it's sending a signal to the NCR, but the NCR isn't sending the signal to the F1 pump? ( I would like to ask you how they verified it, but seems they did that by switching out the NCR).

So the NCR chooses a different way to toggle the F1 pump (after reading the sensory data) when it's running/driving, or with the key in the ignition, than it does when it verified a signal is sent to it from the key fob or opening the door? In this case, the car is recognizing while ignition/running through the pressure sensor it's dropping. The NCR toggles the F1 pump.

But the NCR isn't recognizing the door open/lock/unlock toggle, and so is not triggering the F1 pump at all. Oh sorry, they are saying the pathway for the door/lock/unlock in the NCR isn't responding to send a signal to the F1 pump, but the NCR is receiving the signal.

If you don't mind, since the NCR is damaged and no longer useful after replacement. If I pay for postage would you be willing to ship it to me? I apologize if I am being forward. I love F1 cars and would like to confirm the diagnosis, only if that's okay with you of course. It's just a new set of circumstances for me to see this issue. I would like to plug it into my GS. I have a scan tool so I can also reprogram it with the appropriate data, I would like to do some testing.

 

[Mr K]

Voicey/Maverick, thank you this is very helpful and makes this a far more complicated job than I had understood. Voicey I would love to pick your brain and see how I best resolve this minor but annoying issue!

Craig, Thank you also, let me explain a little more to answer your question.
The car changes gear and runs well, I have no gear change issue at all. The challenge is that when the car is cold, you have to wait 5-8 seconds before it will start, either with the ignition on, or the key trying to start the engine, waiting to the F1 pump to fully charge. (and it does go into neutral when the ignition is on and you pull back both paddles) Also when the car is warm or recently used, it starts immediately.

I have just had the car serviced with Meridien Moderna, having previously noticed the lack of F1 pump noise after unlocking the car, I asked them to investigate the possible cause. They found that when the car is unlocked or the door opened, a signal was being sent to the TCU, but no instruction/signal was going from the TCU to the F1 pump to start the priming. So to verify this they were able to changed the TCU and then the car DID prime, when unlocked (from cold) so they suspect the TCU is faulty. (The F1 pump and relay were changed 18 months ago).

I had the impression this was a quick replacement of the TCU, (rather like the F1 pump relay) but it is clearly not.

This forum is such a wealth of useful information, thank you.

Thinking though this issue, and taking into account Meridien's diagnosis...

The signals to and from the TCU work fine.
The TCU does everything it should correctly, apart from this one scenario.
Could it be a 1 bit corruption of the code causing one logic branch not to fire?
If so, a firmware re-flash could cure it by over-writing the corrupt code with good code...

Got to be worth a try.

 

[James]

I like your thinking Mr K. (and agree with you logic).

Hi Craig,
I will try and explain what I understand the garage did to answer you questions, and I would be happy to ship it to you, I may be in the US next month (if this is the source of the problem).

I would like to ask you how they verified it, but seems they did that by switching out the NCR - I believe they were able to detect a signal being sent to the NCR, as the door is unlocked, (Here I don't know but believe they surmised that no signal was sent from the NCR to the F1 pump. at this point they changed out the NCR and found that a signal was sent correct to prime to pump. When they put the original NCR back into my car, the F1 pump continued to work initially (when unlocking from cold) but on unlocking the following day it did not prime the F! pump and the car took 5-8 seconds to start (as I have experienced over previous months).

they are saying the pathway for the door/lock/unlock in the NCR isn't responding to send a signal to the F1 pump, but the NCR is receiving the signal - Yes this is correct.

In my small brain, I see the NCR working correctly except for the F1 priming when the car is unlocked (after a period on non use). This issue seems to be the lack of a command from the NCR to trigger the F1 pump.

The "work around" is to leave the ignition on for 5+ seconds, as I put on my seat belt and savour the moment, and then it starts immediately (from cold, having had time to prime).

Do PM me and I will let you know how I progress and ship the NCR.