Question about solenoids
Posted: Wed Mar 12, 2014 4:52 am
My Audi transmission uses 7 Solenoids.
5 Shift solenoids. One for TCC and one for PC.
The Audi Self Study Program identifies these later solenoids (N93 & N91) as Modulation Solenoids (PWM)
I can buy a new set of Solenoids easily enough.. http://www.ebay.com/itm/Transmission-So ... 07&vxp=mtr
The two PWM solenoids are identified by having brown connectors.
However, I have a query..
Audi's own troubleshooting guide for this transmissions lists checks for impedance for the 7 solenoids. It shows that all the solenoids should have an impedance of 55ohms.. except for N93 (PC) which should be 4ohms.
When I check my solenoids they're all to spec.
That means N91 (TCC, which has the brown connector and is listed as a PWM solenoid) has an impendance of 55 ohms, whereas the other 'identical' solenoid (N93, PC) has an impedance of only 4ohms (these are values measured at the TCM installed in the car)
Scoping those two solenoids (N91 & N93) I see that:
N93 (PC) has a lovely 440hz square wave signal (59% duty cycle at idle)
N91 (TCC) has nothing
How can two identical solenoids have such different charactistics?
5 Shift solenoids. One for TCC and one for PC.
The Audi Self Study Program identifies these later solenoids (N93 & N91) as Modulation Solenoids (PWM)
I can buy a new set of Solenoids easily enough.. http://www.ebay.com/itm/Transmission-So ... 07&vxp=mtr
The two PWM solenoids are identified by having brown connectors.
However, I have a query..
Audi's own troubleshooting guide for this transmissions lists checks for impedance for the 7 solenoids. It shows that all the solenoids should have an impedance of 55ohms.. except for N93 (PC) which should be 4ohms.
When I check my solenoids they're all to spec.
That means N91 (TCC, which has the brown connector and is listed as a PWM solenoid) has an impendance of 55 ohms, whereas the other 'identical' solenoid (N93, PC) has an impedance of only 4ohms (these are values measured at the TCM installed in the car)
Scoping those two solenoids (N91 & N93) I see that:
N93 (PC) has a lovely 440hz square wave signal (59% duty cycle at idle)
N91 (TCC) has nothing
How can two identical solenoids have such different charactistics?