Greetings. I started up my Impreza (1996, Japanese HX-20s, 4-spd auto, EJ20 engine - basically a non-turbo WRX) today and the Power light was flashing. I used the secret handshake and got a code 16, which as best as I can tell from the charts I've found indicates a problem with the "Torque Control Cut Signal". The symptom is apparently "Torque control signal is open or shorted from ECM".

 

From the "4EAT.pdf" file that is floating around here and elsewhere:

"Torque Control Cut signal is sent to the TCM from the ECM preventing fuel cut under certain conditions...Torque control signal (unique from the Torque Control Cut signal) is created in the TCM logic to communicate to the ECM that torque reduction (fuel cut) is required to reduce shift shock during a wide-open throttle upshift."

It's not clear to me what the Cut Signal does if it is "unique" from the other signal.

 

Are Torque Control Signal and Torque Control Cut Signal just part of the same control loop, solely related to controlling torque when upshifting with the accelerator floored? Torque Control Signal goes from the TCM to the ECM, while Torque Control Cut Signal goes the other way. I realise I might have answered my own question here, but it's very helpful to get some more experienced input.

 

Also, because I wanted to check if this was a problem that needed to fixed right away, or a one-off, I disconnected the battery on the car to clear the TCU. I then took it for a test drive and couldn't get the code to show again.

 

Perhaps I will have to stop flooring the Impreza when the Power button is on. :-(

 

Thanks for any insights.

I wouldn't worry about it, especially if the code hasn't shown up again. If you continue to get the code, then you could have an issue with the TCU or wiring.

has any recent work been done? could be a connector pulled apart partially or something like that.

 

no changes you can feel in shifting or otherwise?

has any recent work been done? could be a connector pulled apart partially or something like that.

 

no changes you can feel in shifting or otherwise?

 

I had Duty Solenoid C replaced last year (August) - the connectors were possibly pulled apart then so that continuity checks could be made on the wiring etc. It seems unlikely it would show up this much further on.

 

I haven't noticed any differences in shifting. The car doesn't upshift from 1 very smoothly when it's floored and the Power button (which makes the car upshift at higher revs) is in, but it seems Subarus aren't particularly smooth there. I'd have to try another HX-20s to compare it.

 

The problem hasn't come back, so perhaps it was just a temporary condition.

 

I'm still interested to know under what conditions the Cut Signal would be sent from the TCM to the ECM to prevent fuel cut.