Bad 4R44E bad,bad

[BrooklynBay]

Did you ever replace the computer? Maybe if you replaced it, they might have given you the wrong one. I once experimented with a computer from a 3.0 FWD that I put in my 3.0 RWD. It worked, but didn't control the transmission's solenoids, so it only went up to about 30-40 MPH maximum. It felt like it was just slipping a lot. The FWD was an AXOD, and the RWD was an A4LD.

 

[nmaineron]

Yea,we did but that doesn't mean that something like you experienced didn't happen.

Anyway, today the boys gave up on me.It will probably end up in my drive in a day or so.They didn't beat me up to bad.They are only going to charge me the labor for removing the tranny to check the TC.They must have a week in just trying other stuff.They are pretty dejected also,doesn't bode well for the shop either.

I'm thinking that the wiring harness is holding the weapon.I'm trying to figure a way to run a 12 volt load through each wire,maybe wire in a light to give me a visual in case there is intermittant current.I will also use a meter for continuity.Now that it is warm out I can give it a good going over.

They ran a bunch of continuity tests but if a couple of wire were melted together you could still get a pass,just thinking and thinking.

Wish me luck! I'll keep you posted.Ron

 

[Doubt Incarnate]

the slow engagment sounds like the tcc solinoid is messed up. if it engaged with the manual switch while the truck was parked it would seem it doesnt have a problem doing what its told provided its not working with much pressure. or as you suspect the oomph ist getting through the wire. you coudl check for stretch marks in the wires or just try and bypass the old wires with new ones.

 

[nmaineron]

Doubt,thanks but I think we did just that(bypass) when we wired in the switch.The whole mystery here is that this is the second transmission with exactly the same problem.Not doubting the solenoid theory but the solenoids were the first items to get attention.The harness has been removed and checked for continuity but not under heat that I know of.That is where I am going to focus first.Ron

 

[BrooklynBay]

If you had these electrical problems with 2 transmissions, then maybe it could be your main vehicle's wiring harness. That is quite a job to troubleshoot, and replace. I know that a break out box could pinpoint everything from the PCM's connector, but what if it is an intermittant, or temperature related problem? That wouldn't show up when it is being diagnosed. When you connected shift lights, and bypass switches, you connected them at the point of the transmission. This would indicate power at the transmission when it is necessary, but might be an erratic voltage, or possibly a voltage that is too low to operate any of the solenoids.

 

[BrooklynBay]

Did you check all of the ground connections? The wires have a constant positive voltage, but the PCM provides a ground to operate the solenoids. The TCC, and EPC are modulated, and require a special transmission tester to check.

 

[nmaineron]

I have a question.If the system throws a code such as the 741 code and it can be a result of various component malfunctions or faults,why doesn't the system give a reason for the fault?For instance,if the TPS is causing the transmission to throw the 741 why don't I get a TPS fault?Ron

 

[Doubt Incarnate]

if the tps was bad youd get a code for it as well. make sure your only throwing one code.

 

[nmaineron]

I have read through a few of the posts here and found a few references to the heat shields.We haven't addressed that in my discussion yet.How much of an issue could they be for my situation and which shields would we be looking for? Ron

 

[BrooklynBay]

There is a heat shield that covers up the 2 servo pistons on the passenger's side of the transmission. This keeps the catalytic converter from drying up the servos. Those parts do dry out over time, and rot. They are pretty difficult to replace while the transmission is still in the vehicle. This will cause the bands to either not apply, or apply with a minimal amount of pressure. They could also apply, but will drop out pretty quickly when the fluid starts to bleed out from leakage.

 

[nmaineron]

I finally got my truck back last night.They have a switch wired into a purple and yellow wire, coming out of the computer, to keep the TC solenoid locked.It works but doesn't make any sense to me why the switch would allow the solenoid to stay locked through this switch and not through the wire,unless......that particular wire was bad.Which leads me to...I need a good wiring diagram,I have Chiltons in front of me which I find confusing and not detailed enough.Are there any good sources online?

 

[BrooklynBay]

AutoZone has wiring diagrams online. Your harness going into your computer might have some bad connections going into the transmission.

 

[nmaineron]

The AutoZone diagrams are the same as Chiltons.They don't include the transmission solenoids.

I stopped into the local Ford dealer and asked if they could help me out with the wiring diagram.They did,copied a few pages out of the shop manual for me, got pretty much what I needed.

My thinking says that the switch really doesn't prove anything except that the solenoid works.When driving around with the switch on to manually keep the TC locked I still get the O/D light coming on and the harsh 1-2 shifts.This only tells me that something external is sending a bad signal to the computer

 

[BrooklynBay]

The TCC solenoid on your model is modulated. If you just apply 12 volts to it, it is only getting a full on, and a full off control set up (like the A4LD). The EPC is also modulated to vary its output.

 

[nmaineron]

Thanks for sticking with me Brooklyn.I now have a CEL which just may turn out to be my friend.

 

[BrooklynBay]

Did you have it scanned? What code are you getting? I'm surprised that it never showed any codes before. Since you were having trouble for quite some time, it is possible that the CEL is displaying something new.

 

[nmaineron]

It has been with me since I got the truck back.I haven't had it scanned yet and I was wondering if the switch is possibly throwing the CEL.

 

[Glacier991]

It is likely the switch, and I'd bet the code is P0743.

 

[nmaineron]

I tackled the truck today,removed the switch and got to exploring and decided to change out the TPS because there was a big difference in resistance between the two units that I had.The one in the truck had 12 ohms vs 5ohms for the other one.Both have the same part #s.I couldn't find anything on just how many ohms a TPS should have so I put the 5ohm one in.

The truck ran worse than ever! The CEL and O/D flashing didn't happen immediately but they did show up.The tranny had a shudder that I didn't have before and it feels that the converter is locked up all the time.

 

[Wrench]

Here’s a quick check you can use to check for a
faulty TPS: First, with the engine and ignition off,
unplug the electrical connector and attach an
ohmmeter between the center terminal and one of
the outer two terminals on the TPS.
Manually operate the TPS by s-l-o-w-l-y opening
the throttle. Note the ohmmeter reading. It should
increase or decrease smoothly as you exercise the
sensor through its full range of travel.
Next, connect the ohmmeter between the center
terminal and the other outer terminal. Repeat the
same test. The ohmmeter reading should again rise
or decrease smoothly as you exercise the sensor.

Now before you jump to any other changes go and get the codes read. It is important to work your way through systematically or your going to end up going nowhere fast.