I suspect my SMG pump got worn out because my hood switch sensor is bad and it runs the pump randomly while the car is parked.
Symptoms:
- The alarm goes off randomly, confirmed with ISTA that it's bcoz of the "bonnet" sensor.
- SMG cog light. Codes for undershooting pressure, and pump activation too long.
So while investigating, I had INPA read digital values from the SMG module and looked at "right" and "left" hood switch sensor values. They looked fine (ie reporting correct hood status - tested by opening and closing the hood and looking at the values), so I could be looking at an intermittent failure.
I always thought that the hood switch was that thing next to the "drug bin" that sticks out and is depressed by the hood. But toggling this thing manually with a finger doesn't change the digital values in the SMG module. So my question is: where are the hood switches really?
My current course of action is:
- diagnose and fix hood switch problem
- replace salmon relay
- top off SMG fluid, bleed system
- investigate possible leaks.
If none of this works then I'll be looking at spending big bucks on SMG stuff (rebuild, pump, accumulator)
Anything else?
cheers!
EDITs:
As I work my way on a diagnostic, I will add here any relevant information.
- Read hydraulic pressure while the car was running at idle. It slowly decreases (which I think is at a normal rate). It's losing about 1.5 bar every time I put the gar in gear/back to neutral (I don't know if that's expected, I guess it is otherwise we would have a perpetual motion machine!! lol... just thermodynamics). Once it drops past a threshold it quickly builds back up. No more cog light at the time of writing... but I expect it to come back as it did before.
Symptoms:
- The alarm goes off randomly, confirmed with ISTA that it's bcoz of the "bonnet" sensor.
- SMG cog light. Codes for undershooting pressure, and pump activation too long.
So while investigating, I had INPA read digital values from the SMG module and looked at "right" and "left" hood switch sensor values. They looked fine (ie reporting correct hood status - tested by opening and closing the hood and looking at the values), so I could be looking at an intermittent failure.
I always thought that the hood switch was that thing next to the "drug bin" that sticks out and is depressed by the hood. But toggling this thing manually with a finger doesn't change the digital values in the SMG module. So my question is: where are the hood switches really?
My current course of action is:
- diagnose and fix hood switch problem
- replace salmon relay
- top off SMG fluid, bleed system
- investigate possible leaks.
If none of this works then I'll be looking at spending big bucks on SMG stuff (rebuild, pump, accumulator)
Anything else?
cheers!
EDITs:
As I work my way on a diagnostic, I will add here any relevant information.
- Read hydraulic pressure while the car was running at idle. It slowly decreases (which I think is at a normal rate). It's losing about 1.5 bar every time I put the gar in gear/back to neutral (I don't know if that's expected, I guess it is otherwise we would have a perpetual motion machine!! lol... just thermodynamics). Once it drops past a threshold it quickly builds back up. No more cog light at the time of writing... but I expect it to come back as it did before.
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