It's alive!!!

[Thunderbirds]

Hopefully you can tell the difference between a slipping transmission and loss of power..

A slipping transmission usually means the engine is racing and you are not going anywhere.

Loss of power usually means the engine bogs down like someone is stepping on the brakes.

Best I can do at the moment....

But it is likely you need to service the fuel system.
You have replaced the fuel filter yes?

Thanks for the reply. You are absolutely right on the difference between the two, that is why it is hard to describe, it is more of a mix without the whole of the symptoms, only some. Thanks for asking to clarify.

To elaborate, no racing rpms/engine when it happens, sudden and brief (1 second at a time) slipping of power that makes the truck 'jerk' at about the 45 to low 50's mph only, but in lower gears the same rpms is fine. It seems to be worse when the engine/fluids are hot. Even more noticeable under demand, i.e. uphill. Once I am past the 53mph it runs great again. Maybe unrelated, but when the transmission shifts into 4th while slightly accelerating (vs harder on the gas pedal) it seems to jump between 3rd and 4th 2, 3, times until well past the 53mph, then smooth again...

Fuel filter is replaced, and I added the water separator. But the symptoms were present before the separator. But after the fuel filter change. Are you leaning towards bleeding? I thought I did a pretty good job on that. The filter is pristine when I opened it back up for the separator.

Next step is a fuel pressure gauge, but how would I best go about that if it happens at higher speeds? Hmmmm....

I was tempted to take a video when it happens, that may be the best for over the internet diagnostics.

Thanks all for helping out.

 

[Thunderbirds]

UPDATE:

I ran the Transmission diagnostic mode and got three codes.

22 - Throttle Position Sensor Circuit Low
38 - Torque Converter Clutch (TCC) Brake Switch Stuck Off
85 - Undefined Ratio Error

I will start getting a plan together, doing some research. Does anyone have any pointers, lessons learned in the past, so I don't chase my tail down a rabbit hole? Not looking for shortcuts, but maybe something to look for.

Thanks!

 

[Mogman]

UPDATE:

I ran the Transmission diagnostic mode and got three codes.

22 - Throttle Position Sensor Circuit Low
38 - Torque Converter Clutch (TCC) Brake Switch Stuck Off
85 - Undefined Ratio Error

I will start getting a plan together, doing some research. Does anyone have any pointers, lessons learned in the past, so I don't chase my tail down a rabbit hole? Not looking for shortcuts, but maybe something to look for.

Thanks!

Do you have the troubleshooting supplement for the transmission?
It has procedures for the codes you have, #85 could be serious as in slipping transmission.
#38 will keep the transmission out of 4th when hot and no TCC lock.
#22 will default to a fixed 35% throttle setting and no 4th in hot mode, this will make the trans shift poorly
It looks like you have some work to do.
Did you not have a trans light while running??? that is something to not ignore.

 

[Thunderbirds]

Do you have the troubleshooting supplement for the transmission?
It has procedures for the codes you have, #85 could be serious as in slipping transmission.
#38 will keep the transmission out of 4th when hot and no TCC lock.
#22 will default to a fixed 35% throttle setting and no 4th in hot mode, this will make the trans shift poorly
It looks like you have some work to do.
Did you not have a trans light while running??? that is something to not ignore.

I do have the supplement, yes. I have been reading and trying to understand the basics. Mind you, until I recently replaced the filter, I've never worked on an automatic transmission, let alone seen the insides live with my own eyes (as our VP would say ) I really appreciate your help/guidance.

No Trans light when running.
I was hoping #85 is a byproduct of the other two, but time will tell.
I am suspicious of my brake switch, for some reason is seems to be intermittent or late to actuate the brake lights.... Not sure how the transmission uses that signal.
#38 sounds right, as symptoms get worse when engine/fluids are hot.

 

[Mogman]

When you step on the brakes the switch that goes to the transmission OPENS to disable the torque converter lock.
There are actually two switches in the brake light switch, the one that opens when you step on the brake (TCC) and one that closes to light the brake lights.
It is a PITA the adjust the brake light switch to work correctly, and they seem to fail often.

 

[Thunderbirds]

When you step on the brakes the switch that goes to the transmission OPENS to disable the torque converter lock.
There are actually two switches in the brake light switch, the one that opens when you step on the brake (TCC) and one that closes to light the brake lights.
It is a PITA the adjust the brake light switch to work correctly, and they seem to fail often.

I will be studying the brake switch position and adjustment as well as the TPS section for the same. I know the TM have a prt in that, as well as the trans supplement has some helpful parts. Thanks for giving me heads up.

We are in the beginning of the Sturgis motorcycle rally, so the next two weeks I'll be off and on able to work on the truck, but I do want to get this figured out and fixed.

 

[Mogman]

As for the TPS the first thing you want to do is check wire tag #355 at the TPS, use a sharp test lead to pierce the wire while still connected to the TPS, if you have .5-4.5V then the wiring is suspect, if you have 0V then check wire #350 for 5V, if you have 5V then the TPS is bad.

 

[Thunderbirds]

Hmmm.

#355 has 0.44V. #350 has 4.99V.

 

[Mogman]

Hmmm.

#355 has 0.44V. #350 has 4.99V.View attachment 928782

That is normal, open the throttle and the voltage on 355 should go up to around 4-4.5V
Now you get to back up to the TCM box and check voltage on #355 at the box, again must be done in run with the TCM connected.
You may need to carefully trim the outer braid back on the harness to get enough wire to work with

 

[Mogman]

If that voltage is on #355 at the box then pull the TCM box (4 nuts under the body) and remove the top, remove the TCM and check for water/moisture in the foam under the TCM.
IF that all checks out stick the box back into the truck (no need to bolt it down) without the top and check for the .44V at D8 on the 32 pin connector (see pic) if the voltage is there and you are still pulling a 22 code (check it again) then the TCM is bad.
If the voltage is not present at #355 at the TCM box then you have a wiring issue.

 

[Thunderbirds]

That is normal, open the throttle and the voltage on 355 should go up to around 4-4.5V
Now you get to back up to the TCM box and check voltage on #355 at the box, again must be done in run with the TCM connected.
You may need to carefully trim the outer braid back on the harness to get enough wire to work with

So, I got 3.78V on the #355 at the TPS, as much as I could open the throttle on that little lever. There may have been some more room past that, but I was dangling over the motor, trying to mind all the "No Step" areas.

#355 at the TCM box is 0.44V as well.

 

[Thunderbirds]

If that voltage is on #355 at the box then pull the TCM box (4 nuts under the body) and remove the top, remove the TCM and check for water/moisture in the foam under the TCM.
IF that all checks out stick the box back into the truck (no need to bolt it down) without the top and check for the .44V at D8 on the 32 pin connector (see pic) if the voltage is there and you are still pulling a 22 code (check it again) then the TCM is bad.
If the voltage is not present at #355 at the TCM box then you have a wiring issue.
View attachment 928784

I'll get on that. Quick question, do I need to disconnect the batteries at any point, like when disconnecting the connector? The fasteners are a real b!tch, original with CARC on them.

 

[Mogman]

I'll get on that. Quick question, do I need to disconnect the batteries at any point, like when disconnecting the connector? The fasteners are a real b!tch, original with CARC on them.View attachment 928785

IT is OK to connect and disconnect the TCM with the batteries connected but never with the truck in run position.
You can carefully use a pair of channel locks on the connector just to get it started, be gentle though.

 

[Thunderbirds]

IT is OK to connect and disconnect the TCM with the batteries connected but never with the truck in run position.
You can carefully use a pair of channel locks on the connector just to get it started, be GENITAL though.

I've got the TCM out, cleaned the fasteners really well, but they aren't budging. Even with impact driver. Now I'm afraid to hit it "really hard". Suggestions? Would it be safe to assume we have voltage or is it crucial to find out?

Thank you for sticking with this...

 

[Thunderbirds]

I reinstalled the box (without opening and testing D, and checked for codes. All were erased, I am assuming that is by design once the power is removed or is there just no condition to trigger any codes? So, now I will be test driving soon and will report back.

 

[Mogman]

Yes removing the continuous 12V that is going to the TCM erases the stored codes.
So you are having problems removing the top screws from the TCM case??
If so before stripping them use something like this (hand impact driver) with a bit that properly fits the screws. (you may already be using one)
You push down and twist in the direction you want to go then strike with a hammer.
Also soaking with penetrating oil may help.

 

[Mogman]

All the ones I have messed with have allen head cap screws, the one you have looks like a poor design, I assume it is an early one.

 

[Thunderbirds]

I have used the impact driver, no luck. Used both bit, wide flat head, and #3 Phillips. Getting to the point of almost stripping the fasteners, but stopped short of that. Used penetrant oil as well.

 

[Mogman]

I would be surprised if you do not find moisture inside, that does not look like a very "tight" box.
Give the penetrant some time, find a flat face punch that fits the dia. of the screw heads and a few whacks may also help.

 

[Mogman]

Since you see the TPS voltage at the TCM box, if you are still throwing a 22 code then the problem is 99% likely in the box.
It is possible that disturbing all those connections may have cleared the TPS problem, why I say to re-confirm the code 22.