P38A Cruise Control repair....I hate this Ba$tard thing. ;-)

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Why does my NANOCOM say the brake Lights are on when they are not? I reset the dump-valve switch (which did turn the lights permanently on until I set it properly).
Is there any interaction between the actual brake-lights and the Cruise Control, other than the brake pedal switch(es)?
 
Yes brake switches do affect cruise control

From manual

Brake Switches
The ECM (Z132) has two brake inputs, each of opposite polarity. Comparison of the polarity states provides the ECM (Z132) with a brake sense (i.e. if switch 1 high and switch 2 low going to switch 1 low and switch 2 high) and so cancels cruise control. If both switches are the same polarity, the ECM (Z132) senses a fault and does not allow cruise control.


But I am sure I have read somebody saying there is a glitch in Nanocom when it shows switch positions incorrectly (but could have been a dream)
Something along the lines of they both show the same when one should be open and one closed and they swap when switched, but think as long as they both switch they are good.

Wait for somebody to confirm thou as I don’t have a Nanocom.

J
 
Thanks Jon, yeah I had read that post before but its more to do with ABS fault I think.
What I seem to have on the car and showing in NANOCOM is where the label "Brake Pedal" status changes OK (on/off) but the label "Brake Lights" stays permanently "ON" and never goes off.
I may pull the brake pedal switch again and see if there are 2 switches and only one of them is working.
However, the physical brake Lights are truly "OFF" and do go on/off when the brake pedal is pushed/released. Very ODD.
 
Yes very ODD.

Unless somebody has been in it before and done something;). Don’t think that’s the case with yours though.

Think having a good look at the switch is a good place to start. As your Nanocom reports both aren’t changing then car brain probably see same and won’t let you use cruise control.

Good luck.

J
 
**UPDATE**
Took the brake switch off and tested that it swaps over NO/NC and back again.
Plugged in the replacement Converter/Inverter unit that the ETG map had said was the likely cause.
STILL NOT WORKING!!
I can hear a relay "Ticking" on pressing Set or Res when the car is going >28Kmh so both switches are working (also confirmed by the NANOCOM "inputs" page in real time).
As predicted by many folks on here it may be time to hot-wire the vac-pump.
 
Can you see what the vent/dump valve switch does on Nanocom?
You say the switches work right but what does the brain see?

Just chucking stuff out there:)

Mine don’t work either but not too concerned as I see bad hoses, and roads here don’t warrant use. Plus my lead foot:D

J
 
**UPDATE**
Took the brake switch off and tested that it swaps over NO/NC and back again.
Plugged in the replacement Converter/Inverter unit that the ETG map had said was the likely cause.
STILL NOT WORKING!!
I can hear a relay "Ticking" on pressing Set or Res when the car is going >28Kmh so both switches are working (also confirmed by the NANOCOM "inputs" page in real time).
As predicted by many folks on here it may be time to hot-wire the vac-pump.

Test 4D in the fault finding guide activates the vac pump. If the pump runs but bellows don't pull in, then there is a vacuum leak somewhere.
 
Test 4D in the fault finding guide activates the vac pump. If the pump runs but bellows don't pull in, then there is a vacuum leak somewhere.
Is exactly where I was going next. But first I will be pulling the unit out and having a good look at it for the obvious signs of it being duff/disconnected somehow. All other items have been replaced (inc. ECU/Hoses etc. and all switches work as they should). I am still puzzled that NANOCOM says Brake Lights are ON when they clearly are not.
 
You can easily activate the vac from the ECU connector. Also open up the vac pump housing & check the small hoses inside. There's a dump valve in there, and the pipes go brittle & crack.

Pete
 
Test 4D in the fault finding guide activates the vac pump. If the pump runs but bellows don't pull in, then there is a vacuum leak somewhere.
Just a daft update really. I took the vacuum pipe from the vac-pump to the throttle-bellows off and stuck a spare section on in its place. Sucking on this pipe pulls the bellows in and they stay in (so the dump-valve is closed OK and the bellows is OK).
 
You can easily activate the vac from the ECU connector. Also open up the vac pump housing & check the small hoses inside. There's a dump valve in there, and the pipes go brittle & crack.

Pete
Hi Pete,
The ETG shows "fused" jumpers being used for that test and I have none. I could use un-fused lengths of wire but its a risk maybe?
 
Thanks Jon, yeah I had read that post before but its more to do with ABS fault I think.
What I seem to have on the car and showing in NANOCOM is where the label "Brake Pedal" status changes OK (on/off) but the label "Brake Lights" stays permanently "ON" and never goes off.
I may pull the brake pedal switch again and see if there are 2 switches and only one of them is working.
However, the physical brake Lights are truly "OFF" and do go on/off when the brake pedal is pushed/released. Very ODD.

Got a feeling Marty mentioned something about this in the past. In one of the screens the brake light switch does switch over for the cars before 1999 but both show as on or off after 99. Also, on the ABS module the wheels are labelled wrong.

There are a few issues with labelling. Maybe the next upgrade could straighten them out if someone reports them.
 
Being a bit of an ar$e with more money than sense :mad: I bought a little test gizmo that does a wide range of measurements and also can be used to power stuff up (if required).
I went to the Vac-pump and tested that the dump-solenoid fired & released, the vac motor ran and the bellows pulled the throttle-cable. All good there.

I re-ran all the tests in the cruise control ETG again with the aid of this little gizmo instead of struggling with a DVM and croc-clips and with my clumsy fingers that are like "cow's-teats"etc. etc.
Much easier to work with (so that's good).
All OK as far as step 3D where it then fails with 0V instead of 5V on all wheels stationary. "Probable-Cause" declared as Yellow-Red wire or BeCM fault. Blast!
If it had passed 3D then the next test (4D) was the hot-wiring of the Vacuum Pump anyway, and I've already proved that that all works.
Never mind, Cruise Control is over-rated anyway ;)
 
Being a bit of an ar$e with more money than sense :mad: I bought a little test gizmo that does a wide range of measurements and also can be used to power stuff up (if required).
I went to the Vac-pump and tested that the dump-solenoid fired & released, the vac motor ran and the bellows pulled the throttle-cable. All good there.

I re-ran all the tests in the cruise control ETG again with the aid of this little gizmo instead of struggling with a DVM and croc-clips and with my clumsy fingers that are like "cow's-teats"etc. etc.
Much easier to work with (so that's good).
All OK as far as step 3D where it then fails with 0V instead of 5V on all wheels stationary. "Probable-Cause" declared as Yellow-Red wire or BeCM fault. Blast!
If it had passed 3D then the next test (4D) was the hot-wiring of the Vacuum Pump anyway, and I've already proved that that all works.
Never mind, Cruise Control is over-rated anyway ;)
May be just a bad connection or could even be cruise control is disabled in the BECM and just needs turning on.
Settings have been known to change as a result of battery problems.
 
May be just a bad connection or could even be cruise control is disabled in the BECM and just needs turning on.
Settings have been known to change as a result of battery problems.
Oooohhhh that's a good point. Will stick the NANO back on it to see if Cruise is enabled. Thanks Keith! :)
 
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