P38A Cruise Control - Armchair theorists required for ideas and help.

Have you double checked the cable is on the right cam and have you double checked the free play.. both in the cable and the cam?

kermit_rr said:

Have you double checked the cable is on the right cam and have you double checked the free play.. both in the cable and the cam?

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Yes and no.
Cable is on the right Cam, free play was checked ages ago, but not recently. I will check it for the required "gap" measurement.
The fact that applying power to the vacuum-pump gets the engine revs through the roof would suggest its not a cable issue, its an actuator issue...No?

DanClarke said:

Yes and no.
Cable is on the right Cam, free play was checked ages ago, but not recently. I will check it for the required "gap" measurement.
The fact that applying power to the vacuum-pump gets the engine revs through the roof would suggest its not a cable issue, its an actuator issue...No?

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the system only works over 30mph, i wonder what stops it working at lower speeds? is that in the ECU somewhere, or something mechanical? if the latter, could something be broke/stuck? guessing now

kermit_rr said:

the system only works over 30mph, i wonder what stops it working at lower speeds? is that in the ECU somewhere, or something mechanical? if the latter, could something be broke/stuck? guessing now

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I would presume it’s just seeing the speed from abs sensors and the cruise control ecu then just won’t let it engage. Presumably for safety reasons as arguably you need to be on the ball more when in area you would be doing 30.

kermit_rr said:

the system only works over 30mph, i wonder what stops it working at lower speeds? is that in the ECU somewhere, or something mechanical? if the latter, could something be broke/stuck? guessing now

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The ECU senses the speed is below 28MPH and says "Threshold Speed Not Met", when you go above 28MPH it changes to "Threshold Speed Met". So I guess it refuses to accept any giddy-up inputs to fire the vacuum pump until the trigger value is seen.

I have put a query on the BBS forum asking for some clarifications on their documentation where actual values returned to the Nanocom for each "Tune" selection differs from the documented values.

AND... I just checked the cable setting. MILES OFF!!!!!!! The CC actuating cam was tight up against the throttle lever actuator instead of 4mm clearance. Now adjusted to 4mm with care.

DanClarke said:

The ECU senses the speed is below 28MPH and says "Threshold Speed Not Met", when you go above 28MPH it changes to "Threshold Speed Met". So I guess it refuses to accept any giddy-up inputs to fire the vacuum pump until the trigger value is seen.

I have put a query on the BBS forum asking for some clarifications on their documentation where actual values returned to the Nanocom for each "Tune" selection differs from the documented values.

AND... I just checked the cable setting. MILES OFF!!!!!!! The CC actuating cam was tight up against the throttle lever actuator instead of 4mm clearance. Now adjusted to 4mm with care.

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Curious where you have gotten the 4mm clearance from? When i read my version of rave it said 0.5-1.5mm clearance

DanClarke said:

The ECU senses the speed is below 28MPH and says "Threshold Speed Not Met", when you go above 28MPH it changes to "Threshold Speed Met". So I guess it refuses to accept any giddy-up inputs to fire the vacuum pump until the trigger value is seen.

I have put a query on the BBS forum asking for some clarifications on their documentation where actual values returned to the Nanocom for each "Tune" selection differs from the documented values.

AND... I just checked the cable setting. MILES OFF!!!!!!! The CC actuating cam was tight up against the throttle lever actuator instead of 4mm clearance. Now adjusted to 4mm with care.

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Dan,
Put an example of the difference between BB Document, and the actual values on the Nano forum as well. Maybe someone on there (who doesn't post here) will compare their results.

When I had my 4.6, I didn't use it at lower speeds but at 80 it held steady, rarely used it though, wasn't very often I had traffic
conditions to maintain a reasonable cruising speed.

pwood999 said:

Dan,
Put an example of the difference between BB Document, and the actual values on the Nano forum as well. Maybe someone on there (who doesn't post here) will compare their results.

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Will do.
I think it is difficult to navigate back & forth on the Nanocom without it having a hissy-fit, so a notepad & pencil rather than photos, might have to do.

I often use mine late at night in 30mph zones, when there's no traffic. Easier to avoid triggering Gatso's that way, plu one route I use regularly has those unmarked white vans with cameras..

Hi folks, I got a response from BBS and they asked me to provide more detail.
Here is a copy of the e-mail I have sent. Apologies that the LZ board S/W screws up the table formatting.
Hi Andreas,
Thank you so much for your reply.
I have now managed to gain access to your forum, thank you!
I have sat in the vehicle this morning and tested 2 AMR5700 ECU’s.
They have slightly different manufacturing dates but the results I get are the same.

Nanocom Behaviour:

If you change the Vehicle type the actual values displayed are NOT updated until you go right out of Hell CC sub-functions and re-enter from the main menu. This is a bad behaviour and will lead to confusion I think.

So, the AMR5700 is SW0000001 Diag Index 01 Coding Index 01 (both units) and one has a build date of 23/11/99 and the other 26/11/99.

Available “Tune” options and values in the Settings Menu, compared to the Hella Manual as is downloadable from your website are as detailed below.


So all I can get from this exercise is that there are NOT 5 selectable “Tune” settings available, there are only “Default”, “Disco II 4.0” and “4.6 Engine” the RR 4.6 and Disco 4.6 are replaced by a common 4.6 Engine “Tune” setting and selecting Range Rover 4.0 fails as the ECU can find no data to load..

From 1999 Didn’t the Disco & the Range Rover both have the same identical Bosch Motronic Thor engine and ancillaries? - Is this why there is just a common “4.6” engine “Tune” option available and no longer a Disco II 4.6 AND a Range Rover 4.6 selectable option as “4.6 engine” covers both vehicles?

Please let me know your thoughts and what you can come up with.



I can take pictures but it is unlikely any mail server will allow an email with that many Mbytes of attachments through and my local provider certainly does not..



Many Thanks in advance.

pwood999 said:

... one route I use regularly has those unmarked white vans with cnuts inside.

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My feelings also.

When I use iPhone pictures for forums or email, I simply transfer them to Laptop, and then reduce the resolution.

Pete

pwood999 said:

Dan,
Put an example of the difference between BB Document, and the actual values on the Nano forum as well. Maybe someone on there (who doesn't post here) will compare their results.

Click to expand...

I did put the whole set of results on the Nanocom forum and they just ignored it and had nothing to say about it not matching their supplied documentation and just asked me if there were any errors in the ECU log. The answer is "No errors reported".


But they said nothing about the reversed logic on the "threshold speed" or the fact that there are not 5 tunes there are only 4 and there is no Range Rover 4.6 only 4.6 engine.

Khemitude said:

Curious where you have gotten the 4mm clearance from? When i read my version of rave it said 0.5-1.5mm clearance

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Workshop manual I have says 0.5 to 1.5mm for pre 1999 and for MY99 onwards says 4mm.

DanClarke said:

Workshop manual I have says 0.5 to 1.5mm for pre 1999 and for MY99 onwards says 4mm.

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Oh interesting, my copy of rave only mentions the 0.5 to1.5mm. I actually used the cruise for pretty much 2 hours the other day and while it did swim a little it wasn’t too bad. Maybe I’ll try increasing it to 4mm and see if that helps mine.

Minor update:
Ruddy thing still does not operate the way it should but it is now "sort-of" trying, but in a very hit & miss fashion.
I have had it hold 70MPH-ish on flat road.
But it still won't accelerate on the SET button (as it should).
Bought some test lead bits (still to be made up) and I will pop the ECU out and hard-wire it for full throttle with ignition at Pos2 and see if the actuator operates ok. Basically this check (its in the ETG) removes the ECU from the equation and checks the final wiring to the vacuum pump actuator.

DanClarke said:

Minor update:
Ruddy thing still does not operate the way it should but it is now "sort-of" trying, but in a very hit & miss fashion.
I have had it hold 70MPH-ish on flat road.
But it still won't accelerate on the SET button (as it should).
Bought some test lead bits (still to be made up) and I will pop the ECU out and hard-wire it for full throttle with ignition at Pos2 and see if the actuator operates ok. Basically this check (its in the ETG) removes the ECU from the equation and checks the final wiring to the vacuum pump actuator.

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Have you checked behind the airbag on the steering wheel for bad tracks in the ribbon?

Mark Piercy said:

Have you checked behind the airbag on the steering wheel for bad tracks in the ribbon?

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Sorry for the late reply, no I have not (scared of air-bags).
But.... Nanocom on live data sees all the button conditions as they occur in real time as you drive along. Set/Rst.

I just executed the troubleshooting test (4D) where you pull the ECU and hard wire some pins (1 &11) and ground pin 7 on the ECU plug and the "pass" is that the pump operates and the throttle is pulled fully open. It pulls the throttle fully open.

It then says go to step (5D) which is more of the same but with both pins 7 & 17 grounded (also a pass) because the throttle fully opens. If you put your foot on the brake it stops the pump and dumps the vacuum and the throttle rapidly returns to idle/off.
If it isn't in a fwd gear or you have your foot on the brake, the vacuum pump never even starts (which is correct).

So, the ETG's conclusion is that the ECU is duff. :-(

But its had 2 ECU's in there and the result is the same. 2 duff ECU's ? Really?

As I say it all partially works at 50-55MPH and it will sit there holding 55 until you hit a steep hill.

So that is very puzzling.

i dont think its the ecu
do you have a nanocom? sorry, i cant remember! that tells you if button presses are registered and what target speeds are set etc