Next on the list of minor annoyances is the Cruise control on the 02...
It was fine, then just stopped.
The light on the switch is off, however, I suspect that is a bad bulb.
I do have difficulty connecting to Hella CC with Nano, but when it eventually does, I get to check all functions.
If the dash switch is not pressed, I cannot ever connect, and if I switch dash off whilst reading data, it stops, so I think switch is OK
Speed input valid, and follows actual speed whilst driving.
Brake light shows ON when pressed.
Wheel buttons show proper response.
Vacuum lines are good, and I swapped in a known good vac pump/ diaphragm module.
Swapped in the ECU from the 99, which is the same part number. No difference.
What I cannot get to change is the "Brake / Clutch switch" status. It stays reporting "Pressed" no mater how I manipulate the
CC switch on the pedal.
So, I have "Cruise Status" DISABLED showing on line one of the inputs screen.
Cruise is "SET" in Becm settings
Anything else to check? I will remove cruise control brake switch next and test on the bench.

As an aside, Oddly, the CC on the 99 is duff as well at the moment. Nano reads same for it as well. Dash switch on 99 does light up.
It is as difficult to connect to with the Nano as the 02.

Tested the Brake / Vacuum switch on the bench.
It was a bit grubby inside, but a quick service and lube of the seal at the end got it working well.
Contacts close and vacuum breaker opens reliably.
Still, nothing I can do to manipulate that input, shorting the contacts, opening the contacts. whatever.
The Nano still reports that switch as "Pressed"
Officially out of ideas for the moment.

You mention Brake/Clutch switch status. The clutch pedal on a manual has another switch to disable the cruise control but on an Auto that is just a dangling 2 way connector under the dash with Yellow/Green and Black wires. If that has somehow become grounded or you have mistakenly plugged it into something else, that would explain it.

Hmmmmmm....
I was able to find a Y/G and black pair, but they are connected to the fuel filler flap release button.
I will pull duct back out in the morning and look again in depth.

Also, I note that on the 99 the Nano also reports the cruise as Disabled and brake /clutch as Pressed.???
Could someone with a Nano and working CC on an Auto trans please confirm that "Pressed" is not normal?
I find it improbable that both have the same issue simultaneously.

As an aside, do the indicator lamps on the CC and EAS override buttons share a common earth or Pos?
I noticed on my test run today the lamp on EAS override button does not come on.
Coincidence that both globes failed at the same time, or the sign of yet a deeper plot on the part of
the P38 conspiracy??

According to the ETM, the fuel flap release switch should have a Light Green/Grey and Black pair on it. The unused one for the clutch pedal switch normally dangles down near the pedals.

Yes, the CC and EAS override switch do share a ground, E0562 (one of the ones behind the RH kick panel) via splice S208. But so do all the other switches on that panel as well as the EAS ride Height rocker. After taking my dash out to replace the AC Evaporator, a number of the bulbs in my switches, that had worked previously, didn't work and all bulbs were blown. They obviously didn't like being disturbed. I bought replacement wire ended bulbs, carefully removed the coloured 'condom' off the old ones and fitted new bulbs.

I installed the later ECU in one of my 1998 P38. If I get time later will have a look to see what Nanocom says.

In the meantime, this is what my 1999 RAVE says about "system disable":

The cruise control system can be disabled in one of
four ways:

1. The Cruise Control Switch (X115) is put in the 0 position, removing the BeCM (Z238) power from the Cruise Control ECU (Z121) and vacuum pump, and erasing the set speed memory.

2. The RES/DECEL Switch is depressed, signalling the Cruise Control ECU (Z121) via the Inverter/Converter (Z249) to disengage the system.

3. The brake pedal is depressed and a vacuum valve in the Switch Vent Valve opens (X112). This vents vacuum to the actuator valve and releases the throttle.

4. The Voltage applied to the Cruise Control ECU (Z121) terminal 1 is interrupted, causing the Cruise Control ECU (Z121) to turn off the vacuum pump and de–energize the vacuum solenoid valve. This voltage path is interrupted when:

• The brake pedal is depressed. With the brake pedal depressed, the Brake Switch Vent Valve (X112) moves to position 1 and the circuit is in-terrupted.
• The transfer gear box is not in Hi range.
• The vehicle speed does not exceed 28 mph (45 km/h).
• The vehicle is not in a forward gear (P, R, or N) (Automatic Transmission).
• The clutch pedal is depressed (Manual Transmission).
• The engine rpm rises above 5000 ± 10% (Manual Transmission).

The BeCM (Z238), which monitors these signals, will then remove power from C1279/Pin 18.

I pulled the duct out of the way again, and had a good look under the dash.
All I found was a small white plug with Violet and Violet/Black wires. It's sort of in the position you would expect the clutch pedal to occupy. Aside from that, I saw nothing amiss.
Looks like a 2000 mile return trip without cruise! Shoot!

The brake light switch and cruise control switch are two separate things, with the latter having the "vacuum dump" valve in it as well. It's well hidden behind the air duct and its main failure mode seems to be that the plastic tangs holding it in place get brittle and it falls off the bracket.

At least that's what happened on both of mine.

The plug for the footwell light should have Purple and Purple/Red wires. Does that work or have you inadvertently connected the clutch pedal switch connector to the footwell light?

You nailed it Gordon, I have now experienced 3of those switches with the self ejecting flange "feature"
I have been successful in the past with a bit of dense foam and a zip tie or 2.
I did remove this one and serviced the seal, and cleaned up the contacts.
Bench tested fine.
I attempted to get a good reading for status with the switch out and just hanging there. No dice.
Pressing the plunger also caused no change in the status on the Nano.
The only thing I didn't try was to short the wires with a croc clip lead.
It's all back together now as I have an early morning departure to do the trip to Southern California.
There is one 98 in a breakers yard on my route. I will grab the switch from there and try it.
Gilbert, I get a dope slap for " forgetting" that as the puddle light had crumbled, it is not there.
I have added puddle lights to my shopping list.
Possibly, as this is an 02 and NAS, it has a slightly different loom without the clutch switch since no manuals were sent across to us.

Just an FYI,. Put my Nanocom on my P38 that has the newer cruise ECU mod to check what triggers the "Disabled" status.

Basically it's showing that cruise is not engaged. Nothing changes it while stationary, but with the car over 20mph (or so), when pressing the SET button that status changed from Disabled to Enabled !! Weirdly with the AC switched off on the dash button, I get the expected communication error, but the status still shows disabled !!

Yet another odd interpretation by BBS. It should be something like Disengaged & Engaged or Active ?

Odd indeed!
Thanks for checking that. I stopped at a breakers yard on my trip down south and scored a pristine plunger switch
And a replacement dash button for the CC from a 98.
I have observed that the plastic used in OEM parts is quite variable with better plastics used in earlier years.
This switch has very pliable flanges and clips and looks like new inside.
I will install it tomorrow and see what's going on.
Oh, gotta say that the beast performed perfectly on the 15 hour 1000 mile banzai run down central California
(No missus or dogs, so just fuel stops and 2 hours at the breakers)
I'm really glad I repaired the HVAC system before leaving. Temperature was between 20 in the north and
78 degrees in the south. Farenheit obviously........
I hope I have Cruise on the return.

Pete, if you have an automatic, and recall what the Nano reports the clutch/ brake switch status as.
Mine always says "Pressed" and no amount of fiddling with it seems to change the status.
Seems to me that if it thinks it's pressed, it is always going to report disabled?
Thanks!

If I remember, I will check on mine later today when I go to the garage to put some parts in the interior that I neglected for a long time.

As Gordon mentioned, for a working CC you need the two switches to work OK, any of them will fail the system.
However, I have experienced a brake switch that would seem to "move", would open/close the contacts when tested with a multimeter, BUT would not work when fitted to the pedal. I still have it in a plastic bag with a sticker that says "?"
So never fully trust the initial check ....

I had also this happening before xmass on a W126SEL that I had to finish for sale, and it drove me crazy for days, until finally I got fed up and just bought a new brake switch and that is it.

Well, it seems I have had the same experience as Leolito......
My switch tested fine on the bench, but did not work when re installed.
I put in the one I got from the breakers and it now works fine!
It was nice to have it for the 1200 mile return trip!
Thank you all for your input!

Bolt, glad you got it sorted.

I didn't think the check the clutch switch status because it's an Auto and cruise works.