Tuscan heater flap stepper motor gearbox ratio
Discussion
I’ve been fixing the heater ECU stepper motor circuitry on a mk1 Tuscan by replacing the square UC3517Q driver IC but now that works I’ve noticed that the stepper motor gearbox has a very low ratio gearbox.
I’ve calculated it to be roughly 200:1.
Can someone please let me know what the ratio should be and a part number if possible? My gearbox is unlabelled but the motor is a 42M048C2U. The previous owner had bought a P0484 from Powers a few years ago so I thought the gearbox should have been correct. I believe the gearbox should rotate 90 degrees on ignition on.
I’ve calculated it to be roughly 200:1.
Can someone please let me know what the ratio should be and a part number if possible? My gearbox is unlabelled but the motor is a 42M048C2U. The previous owner had bought a P0484 from Powers a few years ago so I thought the gearbox should have been correct. I believe the gearbox should rotate 90 degrees on ignition on.
Link to the video of the completed heater flap stepper motor with an additional protection circuit using a micro switch. Not the same idea as has been previously posted.
https://youtu.be/cF0NFajySpI
My circuit board is the Rev 01 and if I used a micro switch to cut a phase at the extreme cold position then the stepper motor wouldn't drive off that position once the ignition cycle had ended. I had to use a timer relay to prevent the stepper motor over-driving for that ignition home position finding cycle that lasted around 4 seconds. The timer I used was:
DC 12V NE555 0~60 Seconds Delay Timer Switch Adjustable Time Relay Module (QF-RD02) <£5
https://www.ebay.co.uk/itm/154284673633
Schematic of how I used this relay.
So the micro switch stalls the motor at the extreme home position by cutting a phase to the unipolar motor during the ignition on homing cycle. Once that ends, around 4 secs, the relay switches back to normally closed and normal connection of the relevant phase (in this example I used the blue wire from the heater ECU to the stepper motor).
Other info is that the UC3517Q surface mount stepper motor IC can still bought from the US or China. Example company is UTMEL (www.utmel.com) with Fedex delivery. Cost is around USD 6 each plus shipping.
https://youtu.be/cF0NFajySpI
My circuit board is the Rev 01 and if I used a micro switch to cut a phase at the extreme cold position then the stepper motor wouldn't drive off that position once the ignition cycle had ended. I had to use a timer relay to prevent the stepper motor over-driving for that ignition home position finding cycle that lasted around 4 seconds. The timer I used was:
DC 12V NE555 0~60 Seconds Delay Timer Switch Adjustable Time Relay Module (QF-RD02) <£5
https://www.ebay.co.uk/itm/154284673633
Schematic of how I used this relay.
So the micro switch stalls the motor at the extreme home position by cutting a phase to the unipolar motor during the ignition on homing cycle. Once that ends, around 4 secs, the relay switches back to normally closed and normal connection of the relevant phase (in this example I used the blue wire from the heater ECU to the stepper motor).
Other info is that the UC3517Q surface mount stepper motor IC can still bought from the US or China. Example company is UTMEL (www.utmel.com) with Fedex delivery. Cost is around USD 6 each plus shipping.
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