FastKat

iTrader: (10)

I tested the shift solenoid signals coming from my 2006 Sierra PCM. When the PCM wants to engage the solenoid, it grounds the wire. I tested the wires that the PCM is grounding, and when the PCM activates the solenoid, the ground shows about 45-50 ohms of resistance. This is true for the A, B, and TCC solenoid.

Does that sound correct, or do I have a problem with my PCM?

FastKat

iTrader: (10)

Anybody? When the PCM grounds the solenoid wire to activate the solenoid, the wire (which is grounded by the PCM) has about 45-50 ohms of resistance at the 20-pin connector that plugs into the PCM. Is this normal or within spec? Or is 45 ohms too high?

BTW, the PCM wires for the shift solenoids and the TCC solenoid have about 45-50 ohms when measured at the connector that plugs into the trans.

FastKat

iTrader: (10)

Nobody knows anything about this?

FastKat

iTrader: (10)

I guess I'll be the first to post some info about this -

I changed out both shift solenoids and the internal wiring harness and everything seems to be working properly. I guess the 45-50 ohm coming from the PCM ground is normal, or at lease acceptable.

slow67

iTrader: (2)

If you measure on the transmission itself, (like for solenoid A, compare pin E to pin A) it should be between 19 and 31 ohms.

FastKat

iTrader: (10)

Yea, I've seen that spec before - I am actually measuring the signal coming from the PCM, not the resistance of the solenoid.

Also, I read some info about people running a direct +12v and ground to the 4L80E TCC PWM solenoid to immediately fully engage it (rather than let the PCM gradually engage it) and some of the info said that this was bad because the line needed some resistance so the solenoid would not burn up. So.... I guess there is some resistance at the PCM for a reason.