Engine: D5244: Voltage drop

[ShadeTek]

It's not something like the air-con or similar switching off or on is it? Does your car have auto start eco saver system that stops the engine automatically if you are stopped and starts again when you raise the clutch? Also, when you press the clutch while stationary, there should be less load on the engine from gearbox drag and the revs should increase. On an issue I have is that if I coast up to a junction in neutral, the revs fluctuate slightly until I stop and then they settle. I must try coasting up with the clutch depressed to see if that effects it.

[john f]

No Rev drop
As you say the CPS is too fragile to deal with serious volts
It must be something that is actioned or connected to the CPS circuit that is causing the niggle
It must also be related to the Cruise control system due to the fact that when the car is above a certain speed all is well
I imagine that that speed is the same as the speed that the Cruise control is allowed to become functional

John F

[4candles]

I thoght that the CPS has an active role in controlling the ETM during gear changes?

To make them smoother i believe..

[D5meister]

"the headlights were dipping on take off
I am measuring with a cheap digital voltage reader plugged into the cigar lighter"

Hi, dont measure any more thats fine, the whole car is dipping.


Often car sensors are fed with constant current - say 50mA so if there is a short the current is still 50mA.

As the R changes on the sensor, the voltage across it changes and that is the signal.

So I find it confusing. Sounds more like a pinched wire to bodywork - but not on the sensor? even though it doesnt do it with it unplugged.


can you get the sensor off - but plugged in and do the clutch and monitor thing. see if theres a red herring anywhere



with the sensor off - but plugged in can you actuate the sensor by hand and monito the volts see if just motion of sensor does it without chance of clutch motion doing a pinch.

[john f]

can you get the sensor off - but plugged in and do the clutch and monitor thing. see if theres a red herring anywhere

with the sensor off - but plugged in can you actuate the sensor by hand and monito the volts see if just motion of sensor does it without chance of clutch motion doing a pinch.[/QUOTE]


Hi
Car on Idle 14.1 volts
Disconnected switch mechanically and operated by hand without clutch pedal movement
Actuated plunger and it will drop to 12.9 - 13v every time for 30 seconds or so

I don't think I will investigate further I will just see what happens
as long as it stays above 12v I,m sure it should not be a problem
The Dimming lights annoy me though


John F

[D5meister]

I was concerned that the motion of the clutch pedal or any of the linkages was rubbing a loom or pinching a wire loom.

I guess you can now prove it is none of that.

The sensor is new also..

I will try and find some wiring drwgs see iff anything jumps out.