Hey there folks, this is a first so I hope starting a new thread on this is the correct thing to do.

My 01 f150 CC fx4 is hanging the 4r70w out back of a 5.4.
Started having some trouble with the 1-2 shift. As I take off from a stop it seems to go into neutral. I can usually increase rpm's and then it bangs into gear. MIL on, DTC 0755 shift solenoid B (replaced the solenoid pack) also had a 1745 shift (solenoid B) inductive signature error. Read somewhere about this being a pressure issue so I went ahead and picked up a EPC solenoid also. There was no change. Fluid and filter are new and tranny has about 20,000 on a rebuild. Really considering pulling the tranny so I can flip it over and check out the actuators (I think that's what there called anyway.) Any advice or thoughts would be greatly appreciated.

 

Are the codes now gone?
If the truck will move in first and reverse it is not the pressure control valve.
If the B solenoid does not gate pressure to that servo, second will not operate and solenoid A has already released..
Good luck.

 

The inductive signature error has nothing to do with pressure. That code sets when a solenoid is commanded on and the PCM detects that the solenoid didn't turn on. I'm not surprised that a new EPC didn't help. Cleaning the windows on the truck would have helped more than changing the EPC. At least you would have had clean windows.

The ONLY way a P1745 can set is from a stuck shift solenoid. There is no other possible way.

I can't help you here. I have no idea what you're referring to when you say actuators. I don't know what flipping the trans over is going to expose that might be called actuators.

 

I still get the 0755 shift solenoid B. Haven't seen the other again. Reverse works just fine, it's right off the start where the issue always occurs.

 

[QUOTE=Mark Kovalsky;16817530]The inductive signature error has nothing to do with pressure. That code sets when a solenoid is commanded on and the PCM detects that the solenoid didn't turn on. I'm not surprised that a new EPC didn't help. Cleaning the windows on the truck would have helped more than changing the EPC. At least you would have had clean windows.

The ONLY way a P1745 can set is from a stuck shift solenoid. There is no other possible way.


I can't help you here. I have no idea what you're referring to when you say actuators. I don't know what flipping the trans



How about accumulators Mark and as far as pulling the tranny, this keeps me from dumping parts in my shop floor unnecessarily. Thanks for the answer, think I'll go clean my windows now.

 

After rereading my original post I realized that I did not mention that I was replacing the shift solenoid already when I decided to replace the epc as well (since I was already in there) and I had read that I could have a pressure issue. As I said nothing changed in the shift but I have not seen the 1745 code again, just the 0755 shift solenoid B. I'm shooting in the dark on checking the accumulators and getting it out of the truck is the only way I can be sure that when I start pulling the bottom out of it parts don't go bouncing across my shop floor.

 

Decided to pull the valve body today and take a look and see if anything stood out. Accumulators, and valves seem to be in good working order to my untrained eye. No obvious signs of wear anyway. I have replaced the shift solenoids, tcc, and the pressure regulator.

Could there possibly be a bad wire or connection causing the shift solenoid to malfunction and create a neutral like scenario just within the first shift?

 

Yes there could. The P0755 can set from either a bad solenoid or a wiring problem between the PCM and the solenoid. Since you've already changed the solenoid, it's almost certain that you have a damaged wire between the PCM and the transmission connector.

The accumulators cannot cause this. Taking the trans out won't help fix this problem, it is almost certainly not inside the trans.

 

Mark, how about a bad driver in the PCM?

 

That's possible, but not likely.

 

If the PCM detects the B solenoid fault it cannot be the PCM.
The PCM has a means of looking at the current signature of the solenoid operation as the way it detects a fault.
There is a harness from the outside plug to the valve body to each solenoid.
They can go into fault.
There are lead types and ribbon type harness depending on the year.
The operational fault detection can see an open (no current), a short to ground (excess current) , a cross to another lead (the current still will be affected at the wrong level and even time), intermittent and normal expected current signature.
The PCM is equipped with software is triggered by these faults and assigned codes to tell you what is happening.
A look at the DTC list shows you five possible codes assigned for 'each' Solenoid.
The 755 is an error meaning the circuit is complete but the signature is not correct for some reason.
Good luck.

 

That's true, but it will set a P1715 for that error.

This code is P0755. It can only set from an open or short in the circuit, not from an inductive signature fault. It can set from a wiring issue, a bad solenoid, or a bad driver in the PCM. But bad drivers are rare.