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Discussion Starter #1
Hi all, I have a P1640, which is ACTTRQ Motor Torque Signal Circuit Low Input. I've had it for a couple days now. No Regen, no assist, no auto stop... and CEL is on. I'm using OBD ver4BITLCD_V10B. When I go to clear the code, the CEL goes off, and charging starts, then 3 or 5 secs later, CEL comes back on and charging stops. I've done a grid recharge, pulled the fuses and still there. I've disconnected the battery and CEL disapppears for about 10 sec.
Any help would greatly be appreciated.
 

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ACTTRQ is a pwm signal from the MCM to the ECM on MCM connector C5 (Yel/blk) wire IIRC.

It's a pretty simple signal that probably varies duty cycle depending on IMA motor torque.
There is a pull down open collector transistor in the MCM and a pull up resistor in the ECM.
If you check with a multimeter to ground at the MCM end there should be some voltage present, maybe 2.5v or so.

Failure is fairly unlikely in either module, so check for bad connections / continuity between the MCM/ECM on the appropriate wire.
The 'low input error' indicates to me the wire/connection is broken, as it's probably fed into an integrator in the ECM to provide a variable voltage depending on the pwm duty.

If continuity is good then swap the MCM for another and see what happens.
If that doesn't fix it then you can swap the ECM or get a scope / multimeter on the line and see what is happening.

Unplug and replug the appropriate MCM connector C and whichever one it is on the ECM.
The two big IMA harness connectors behind the seats under the rear IMA crossmember are also good for bad connections.
 

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Discussion Starter #4
Thanks Peter, I'll get this cleared over the weekend.
 

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Discussion Starter #5
I saw that pdf, but didn't understand what it meant. Now that I see it, along with your explaination, I guess it means exactly what you said - that the probibility that it is either the ECM or MCM failing is slight since other things would show up so it is most likely the connection between them.
 
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