Hi guys,

just put around 200 miles on a remanufactured 4R55E which is classed as a stage 1 that's been upgraded and updated. Got an OD light flashing yesterday while driving and code was PO741 for the TCC. I know my speedo is off and I am waiting on a couple other gears for the VSS so I am wondering if this causes the speed to be 5 mph out at low speeds and up to 10 mph at higher speeds, would this casue the PO741? Just a thought but would like to get some feedback and hope it's not anything inside of the tranny that's acting up so soon.

Thanks

 

P0741 Torque Converter Clutch Circuit Performance or Stuck Off

These are the codes the computer can chose from for the TCC system
P0740 Torque Converter Clutch Circuit Malfunction
P0741 Torque Converter Clutch Circuit Performance or Stuck Off
P0742 Torque Converter Clutch Circuit Stock On
P0743 Torque Converter Clutch Circuit Electrical
P0744 Torque Converter Clutch Circuit Intermittent

You should always look up any code on a FULL LIST first, the codes the computer did NOT use can be as important as the code it did use

Computer didn't use malfunction, electrical or intermittent codes, so probably not a wiring issue, i.e. voltage is passing thru the TCC solenoid back to computer like it should

But computer is seeing torque converter slipping when it should be locked by the TCC solenoid being activated
Its "possible" it's a speed issue but unlikely
When the computer activates the TCC solenoid it would then expect engine RPMs and speed RPMs(output) to be locked, so when one goes up or down the other follows, because torque converter is locked
If your speedometer is drifting up and done when at the same speed then "maybe" that would cause P0741
But if speed is just off but consistent then probably not the cause

A torque converter should slip, that's how you can stop "in gear" without the engine stalling
The TCC solenoid activates a lock inside torque converter once vehicle is above say 35MPH, this makes the vehicle more efficient for MPG and performance
The MPH(speed) the TCC is activated is irrelevant to the results the computer expects, which is the engine RPMs and the transmission RPMs to be locked together

Torque converters also have a Stall Speed lock, usually about 2,500-2,800rpms, if you are in gear, foot on the brake and push down the gas pedal when engine gets to about 2,500rpms engine will start to "stall" unless rear brakes can't hold, lol, because torque converter has locked up so all engine power is going thru transmission to rear axle, so either the rear wheels start to spin or engine stalls

In my day, this was called a "Power Lock", you let the rear brakes break loose while front brakes hold and do massive burn outs

 

Thanks again RonD for your helpful info. So I guess you are saying it's probably the TCC solenoid or the TC itself. The TC is a reman as well (TC REMANUFACTURING F57SDAA). I just read something else that you wrote as well so I hope that's the only cause (the VSS and engine rpm are not synced correctly for transmission setting. I also notice if I just cruise with light throttle and the rpms stay low it doesn't happen but when I give 50% throttle for a couple of shifts it may not lock in OD but 90% of the time once under normal throttle it's fine.

 

Not the solenoid itself or you would get a different code, could be the valve the solenoid operates is "stuck" or the torque converter is not locking when TCC activates

Not sure of the exact strategies Ford uses when accelerating, it may deactivate TCC so its not "jerky" when there is a big change in throttle position??
Unlocking torque converter with big change in throttle position would make things smoother but you would lose performance

 

Contacted the company I got the trans from because I have a 2 yr warranty and told them what's happening and the code and one of their top techs said he's sending me a replacment TCC solenoid so all I can do is wait and see how it goes after I install that one.

 

The day after it threw the PO741 I drove it 2 miles down the road and it started to flare from 2-3 and the reverse started to delay a bit. Contacted the company again and told them what it was doing and they said sounds like a valve body issue so they built a valve body with a sonnax zip kit and sent it out to me. I installed that today and took it out for a test drive.

After 8 miles of driving with trans temp at 120-130 the OD Off light starts to flash again so I turned around and headed back home. Scanned it and the same PO741 code is back and pulling up to my drive way, I put it in Park to get out to open my gate and when I put it back into Drive it barely moved. I had to give it a bit more throttle to get it moving and trans temp still under 150, felt like the brakes were on but reverse was fine. Would a bad torque converter cause this kind of stuff?

 

Hi, does anyone have a computer pinout diagram for this 95 4.0? I can't seem to find my particular one only for the smaller engine or different years. I want to check the trans shift solenoid pins.

Thanks

 

1995 to 2006 should all be the same regardless of engine or transmission, these used the EEC-V 104 pin computer, even manuals had the solenoid wires at the computer until 2002 I think

Automatics in Rangers from 1995 to 2006 all used the same computers and wiring, just the software was different in regards to engine size and shift points
In 2007 Rangers got the 3 connector computer style, same computer just 3 smaller external connectors instead of the 1 large connector so pin numbering was different

1997 diagram below with wire colors and PCM(computer) pin numbers
The 4R and 5R transmissions have exactly the same wiring for the 16 pin connector on drivers side of transmission, and at the computer

All the solenoids get/share 12volts with key on, the wires to the PCM(computer) are grounded in the PCM to activate that solenoid
A solenoid is just a coil of wire around a metal core, so 12volts IN = 12volts OUT, so with key on the PCM should "see" 12volts on each of its solenoid ground wires, if not it will set a transmission code indicating which solenoid is not sending back 12v on its ground wire

Solenoids 1, 2, 3 and Coast clutch, are also known as A, B, C and D

 

Thank you RonD, I wil do some further testing and see if I come up with anything. Also, with the new valve body installed I am now getting more codes. There's the PO741 that's been coming up, then there's PO731 and P1751.

 

P0741 Torque Converter Clutch Circuit Performance or Stuck Off
P0731 Gear I Incorrect ratio
P1751 Shift Solenoid A Performance

And how did the OHM tests for TCC solenoid and solenoid 1(A) come out?
Are the wires connected inside the transmission, correct OHM range

2 new codes indicate solenoid 1(A) is not working like it should, its not showing its disconnected(high OHMs) but its valve is not working like it should

The solenoids control valves that route Pressure to the clutches and bands(brakes) to select different "gears"(ratios), so P0731 and P1751 are about the same issue, solenoid 1(A) valve is not working like it should

 

Hi guys,

update on this issue and it turned out to be the torque converter itself. I guess the QC inspection or test didn't reach this unit. I removed the trans and replaced the converter with a new unit I ordered and it has been over 500 miles since and no codes or high temps or weird shifting. Works great and very pleased with the unit now.

 

Good work

Not a common issue but can happen........obviously