- SOLVED - Stack unit stopped displaying RPM - 2012 Duratec R500

[Shortshift]

(Solution posted separately, lower down in thread)

Right...

2012 R500 Duratec with Stack ST868 instrument pack (the triangular one, configured to show various parameters in the bottom section of the display under the circular rev counter, driven by a stepper motor).  Also fitted with full-fat ACES shift light system (the adjustable one, with box and buttons located on bulkhead under dash).  MBE 992 ECU.

Anyway - the rev counter has stopped.  Suspect that the stepper motor (common culprit) is OK as the needle moves fractionally in reverse direction on start up (as normal) but then refuses to register positive rpm.  The ACES unit is also not functioning properly - it shows the green 'change down' lamp but nothing else - no oranges or reds as the revs increase.

Car drives perfectly well and plugging-in Easimap shows accurate rpm read out (which I assume is taken from the same ECU output as is used to drive the Stack unit and the ACES unit)?

So - logic suggests this is a wiring or connector problem somewhere between the ECU and the Stack and ACES units. 

Following this line, and trying to work back to the source of the problem:

• Can anyone tell me what pin I should be checking for, for rpm, on the 'military spec' 19-pin connector that goes into the back of the Stack unit? 
• And, assuming all I can do is check for continuity between that pin and the other end of that wire in the ECU connector, what pin should I be looking for on the ECU connector?
• Or is it possible to check for the rpm signal using a multimeter onto the correct pin on the military-grade connector?

And - does anyone have any better or further ideas?!

James

[Jonathan Kay]

I've got a recent Assembly Guide with a schematic diagram for a 19 pin round connector on the main chassis harness for a Stack dash. I can't be sure if it's right for your model. Send me a Private Mail with your email address if you'd like a copy.

There was a recent problem that was a bit similar. Disconnecting the engine speed signal from the tachometer to the ACES unit helped to track it down.

Jonathan

[Shortshift]

Thanks Jonathan - that info should help.  PM with email address sent.

James

[Shortshift]

Thanks Jonathan for the pdf copy; not the easiest set of wiring diagrams to understand!

Although it shows R400 wiring and I can see that the engine-harness to body-harness connector is different to the one fitted to my R500, it might well be that the primary wiring is identical...  On that basis I can see one consistently coloured wire (WB - so white with black) which runs from the ECU to the Stack connector; it starts at the ECU as WB72 and runs from Pin 34 on the ECU connector through the engine-harness/body-harness connector where it continues as WB180 to the ACES take-off, with a further extension as WB155 going to Pin A of the Stack conector.

So - if (i) the R400 and R500 wiring fundametals are identical, and if (ii) my interpretation of the wiring diagram is correct, then I need to test for continuity from ECU pin 34 through to Stack connector pin A.

Any further thoughts, views of information would be much appreciated!

James

[Simon.Rogers]

James

If you need to speak to Stack do it Very Quickly.  I received notice that they are withdrawing from UK/Europe at the end of the month and they have nothing in place to effect ongoing repairs at this time.

[Jonathan Kay]

On that basis I can see one consistently coloured wire (WB - so white with black) which runs from the ECU to the Stack connector; it starts at the ECU as WB72 and runs from Pin 34 on the ECU connector through the engine-harness/body-harness connector where it continues as WB180 to the ACES take-off, with a further extension as WB155 going to Pin A of the Stack conector.

So - if (i) the R400 and R500 wiring fundametals are identical, and if (ii) my interpretation of the wiring diagram is correct, then I need to test for continuity from ECU pin 34 through to Stack connector pin A.

I can't confirm that but what I'd try quite early on is disconnecting (what you think is) the engine speed signal to the ACES unit. In the other problem that disconnection made the tachometer work normally and suggested the fault was in or near the ACES unit.

Jonathan 

[Jonathan Kay]

If you need to speak to Stack do it Very Quickly.  I received notice that they are withdrawing from UK/Europe at the end of the month and they have nothing in place to effect ongoing repairs at this time.

That's worrying.

1. What documentation does anyone have on the fitting instructions?
2. Has anyone got an internal circuit diagram?
3. Has anyone ever had one repaired elsewhere? (JDO says that he doesn't do DIGITAL DISPLAYS.)

Thanks

Jonathan 

[Shortshift]

Solved!

A helpful PM to me from L7 FST explained that he had experienced a similar issue which was resolved by changing the CYL (or ES) setting within the Stack unit.  Sure enough, on investigating the various settings buried within the Stack menu structure, I found that ES was set at 4 (cylinder count).  I changed it to 1 and - bingo - all back to normal, it seems (static test in garage only, so not yet tried on the road and maybe carbon monoxide was affecting my judgement?).

So why had the setting changed?  I don't think it had but, recently, Caterham Cars had reflashed my MBE ECU so I am beginning to think that the latest map/software they downloaded might give a different rpm output from the ECU than when the car left the factory, requiring a different ES setting in the Stack unit to work correctly.  Either that or serious inadvertent finger trouble...

Anyway, posting the detail in case it is of help to others in the future.

James

[Jonathan Kay]

Well done.

Please can you confirm that changing that fixes both the displayed engine speed and the ACES functions.

Jonathan

[Shortshift]

The ACES unit also needed to be changed so that the cylinder count setting (which was 4) is now also set to 1.

Adds credence to my view that the cause of the problem was in the reflashing of my ECU (pointing to a difference in ECU rpm output configurtion between the time of my car being built in 2012 and the latest software being provided in the last few weeks).

James

[Jonathan Kay]

Hmmm...

Thanks

Jonathan

[Simon.Rogers]

[John Vine]

... I found that ES was set at 4 (cylinder count).  I changed it to 1 and - bingo - all back to normal,...

Very interesting.  That's how I solved the problem with my R400D ACES settings.

JV

[7 Minder]

Bit of a thread resurrection. 

The RPM needle on the Stack dash stopped working on our car recently.  Following a very helpful discussion with 213 Performance (Stack service agents nowadays) it turns out this was due to a low internal battery in the Stack unit.  

The Low Internal Battery warning appeared a couple of months ago but I was waiting till the winter layup to get it sorted.  Apparently when the battery depletes below a certain level, the programmable dash settings revert to factory defaults.  The ES setting defaulted to 4 but resetting it to 1 restored the RPM needle operation.  I suspect it will have defaulted back to 4 next time I start the car.

The car was originally built from a 2003 kit which included the Stack dash.  It was rebuilt to 420R spec around 2014 by the original owner before we bought it in 2016 but I don't think the Stack battery has ever been replaced. 

[Budjuggler]

Ignore!