Very frustrating Transmission issue... please help!!

[JAnderson07]

Hello guys,

First off....
Im new to the Ford Ranger community, BUT I do have an automotive tech background. AND I have researched and have done some troubleshooting before posting here....

I have a 98 ford ranger xlt with the 3.0l v6. Automatic transmission which according to my research is the 4r44e. I just recently purchased this truck (got a hell of a deal) so I don't know the background. Apparently the trans was replaced not to long ago...

The Problem...
The transmission is stuck in what I believe to be 2nd or 3rd gear, and it feels like the torque converter clutch is stuck activated (idling very low and very sluggish once starting off). I also found the wire at the trans connector for the TCC solenoid and applied power while driving and the truck reved higher while driving, making me believe it disconnected the TCC. I could be wrong.

The FAULT CODES:
P0743 TCC circuit Electrical
P0750 Shift Solenoid A
P0755 Shift Solenoid B
P0760 Shift Solenoid C
---------- other codes
P0141 O2 sensor (have an exhaust leak before sensor)
P1401 Differential Pressure Feedback EGR Circuit, High Input.

With multiple trans electrical codes, of course first things I checked were fuses and relays and harness. No visual damage and I have power at the fuses and relays. I removed the fluid and pan. Trans fluid was pretty clean, sludge over the pan magnet, but no metal shavings. I checked and found there was power at all of the solenoids. I also ran power to each solenoid and heard them all activate (I DIDN'T ohm out the solenoids though...). I put a new filter gasket and fluid. And the same issue still exist...

QUESTIONS
Does this sound like a valve body issue?
Does the Valve body plate/gasket issues apply to the 4r44e trans, or only the 4r55e and 5r55e?
Is it common to maybe have a issue with signals in the PCM?
Are the Valve body's programmed and VIN matched? Or can I grab one from the junkyard and clean up, buy new seals gaskets, and solenoids?

Any help would be GREATLY APPRECIATED!!!!

THANKS GUYS!

 

[JAnderson07]

Also, the internal transmission harness looked great. No insulation was damaged or missing...

 

[RonD]

DPFE sensors usually last no more than 70-80k miles they get moisture in the hoses from exhaust which fouls the sensor, check the two hoses for water/moisture.

The 4R44E was same trans as A4LD but with more computer(PCM) control
In the A4LD the solenoids shared 12volts from 1 wire.
The PCM Grounded each solenoid to activate it.

4R44E looks to be the same, diagram below, the light Blue/orange stripe wire at the transmission is the "power" wire for all the solenoids, pins 1, 10 and 11 on the trans connector
Then PCM grounds each solenoid to activate it.

Soft parts fix on these transmissions last about 12 to 24 months

When having an A4LD rebuilt, there are a couple of things that you need to make sure of. First and foremost, do not let a shop do a soft parts fix only (clutches, servos, and bands). This will almost ensure that you will have another repair needed right after the 1-year warranty is out. Other things you want to have replaced are: forward one-way clutch (always), overdrive drum (stamped tin, replace if out of round or heat damaged), pump (Ford only, rebuilds are prone to failure), and the converter (get the better converter with the improved lock-up clutch and brazed fins).

Yes, the valve body gasket was a known issue, replacement has gasket bonded to plate.

Since you are basically getting all the transmission trouble codes check the fuse and check that you have power at the transmission, light Blue wire
PCM doesn't "share" grounds internally, so if one of the PCM's Grounds is loose or unhooked then PCM couldn't control solenoids

 

[JAnderson07]

Thanks RonD for the input!

I found a similar diagram online that seems to fit my vehicle. The diagram you attached has different wire colors than I do. For instance, the diagram you provided says that the power to the transmission connector is light blue. But the wire colors on my truck are red, in accordance with the diagram I have. (I will attach the diagram I have).

I have 5v at the power supply wires to the trans connector (pin 1,10,11). It just so happens that those are involved with my error codes, and they all split off of 1 wire in the harness.

Is 5v at the trans connector normal? Or should it be 12v?

Also I traced the negative side wires from those solenoids to the PCM and with the key in ignition 2 I'm not getting any voltage at the connector for the PCM.

Shouldn't that 5v carry all the way through the solenoids and back to the PCM since the PCM is what controls that circuit?

I haven't done a resistance test on the wires from the trans connector to the PCM yet (to check for a break in the circuits), i ran out of daylight. Will test tmrw.

Any other input???
Thanks.

 

[RonD]

Yes, sorry my mistake on reading the schematic I posted.

The Red wire from pin 97 on PCM just says Power, could be 5v as that is common voltage used by PCM as VREF(pin 90), it runs to fuse #13(15amp) in engine fuse box, then light blue/orange stripe wire runs out of fuse to trans connector.

They could have run it direct and by passed the fuse, so you have 5v red wire at connector.
And yes with connector plugged in each solenoid wire should show the 5volts at the PCM since solenoid is just a coil of wire, like a light bulb.
Then PCM Grounds that 5volts internally to activate the solenoid.

If you measure voltage at a light bulb and get 5volts on both terminals bulb will be off, if one of the terminals is Grounded(0 volts) then bulb will light up because power is passing thru the bulb from 5 to 0 volts(actually it goes the other way but that's another story).
Solenoid is the same, 5 volts on both wires means solenoid coil is OK, and grounding one side should cause it to activate.