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When setting up GP PWM outputs, how do others find the frequency of the output they are controlling?
By testing an existing functional circuit? I've used the Link Training but there's no mention of frequency in the GP Outputs section.
It's going to be very dependent on the particular output or solenoid you're trying to control. A boost control solenoid for example may need to be operated at 15-30 Hz, while a cam control solenoid may operate at 200-300 Hz. Experience will help guide you on what sort of frequency a solenoid will operate at, but this obviously isn't much use when you don't have experience. What you can do is use the PWM Test option and vary the frequency to the solenoid you're going to use. You should be able to hear the solenoid clicking (or buzzing at higher frequencies). If the solenoid suddenly stops emitting any noise as you raise the frequency, you've likely exceeded the range it can handle and you'll want to drop back into the useable range.
Basically if the frequency is too high the solenoid can't respond in time and will just stick in one position. you'll notice this in operation as you'll lose control over whatever it is that the solenoid is operating. If the frequency is too low, you may get poor control and oscillation.
You got it in one! having very little experience makes it a little tricky but thanks to HPA I'm slowly gaining that knowledge base.
The circuit I'm looking to control is Line Pressure Control for a RE5R05A Jatco Trans. As when I come into boost I'd like to have more control over trans line pressure. I'm quite apprehensive as I do not want to lose line pressure and cook a clutch pack just yet. I'll have a gauge on the trans so hopefully I won't have any issues if there is any control problems.
That isn't something I'm familiar with controlling unfortunately so i can't offer any first hand experience. I'd assume it will want to operate at quite a high frequency to achieve good control but I'd suggest talking to some auto trans specialists and see if you can find how this solenoid is controlled normally.
Thanks for the advice Andre,
From the OEM manual it is a duty cycle based solenoid that and the plan was to find a port if possible on the trans to measure line pressure against the parameter on my NDS2 software.
The OEM manual is quite vague in regards to actual output pressures and figures. This is their description of operation below.
The line pressure solenoid valve regulates the oil pump discharge pressure to suit the driving condition in
response to a signal sent from the TCM.
The line pressure duty cycle value is not consistent when the closed throttle position switch is “ON”.
To confirm the line pressure duty cycle at low pressure, the accelerator (throttle) should be open until
the closed throttle position switch is “OFF”
There is a pretty decent RE5R05A specialist here in Aus, I'll take your advice and give him a call.