Help with 4r70W going forward in reverse, limp mode-error code

[nvrstuk]

Dang, the ONLY thing I barely touched in the ENTIRE 10 month build and it craps out on me!

I have made 3 trips to town as test drives since yesterday's first drive after a 10 month build. I pull up to the Post Office and it won't shift into reverse... Winters shifter is in R but I go FORWARD while the shifter handle is in the R gate.

I drive off and it's in limp mode it seems like. Won't go in any gear but 2nd.

Drive it home at 40 mph in 2nd for miles, tried putting it in N at a stop sign just to see what would happen and it went into 1st gear... made it home, pulled in the shop since I thought maybe my shift linkage was loose or had slipped-(really just hoping for something so simple)? I crawled underneath...nope-tight.

I checked the Baumann controller readout and P is P, R is R, N is N, etc as I move the Winters shifter so I know the range sensor is at least reading where the shifter is but WHY is it giving me these weird symptoms?

The readout on the controller I think said eR5...no such code but eRS is range sensor is bad... are these the symptoms?

Can't believe this...all I did was change the fluid, disconnect the linkage since I did internal KluneV work and replaced the Atlas with the 205... could a loose wire cause this code but I can't find a loose wire in the plug in connectors

 

[nvrstuk]

Not sounding good... maybe the sun gear and clutches are welded???

I was supposed to leave for Moab in 2 days...

I'm going to check the oil...then pull the pan...then ...

 

[garberz]

Sorry to hear after all that’s been going on in your build. Sure sounds like the range selector may be the issue.

Mark

 

[Broncobowsher]

In park, does park hold? Will the engine rev freely when in park? Or does it feel like it is in gear and loading the engine up?

2nd gear is fail safe. 2nd gear with no engine braking. If you loose power to the shift solenoids you can get home or at least off the road this way. Lack of engine braking will keep you from zinging the engine (it will only rev to the limiter).

Trying to move forward while the shifter is in reverse. This isn't a great sign. I'm thinking you have a valve body issue. I don't remember the clutch engagement protocol at the moment. 1st gear while in neutral is also rather odd.

I would start by taking off the shift linkage and MLPS and reinstall them again. Checking the readout on the controller. Beyond that things will start being internal.

 

[nvrstuk]

Yeah, not great timing huh!!

In Park you can feel the engine load up...like power braking but probably working against the park pawl...

I pulled the fuse to the Baumann so I would be in limp mode and the symptoms are the same.

I checked the movement of the MLPS and the movement of the shift rod going into the tranny and they both seem ok, but I did not remove and re-install.

 

[nvrstuk]

Thanks guys...

What's the best way to isolate the problem?

Pressure test

True that electronics can't cause this?

MLPS is adjusted correctly... Thin line to thin line for neutral, correct?

Even if the neutral line is off a little (it's not), how would it "command" it to go forward when it Park?

 

[nvrstuk]

Not trying to get this going in the next two days...pretty much done with putting in 18hr/days/7days/week (literally for months) for the trip in 2 days...wow, do all this work, not work on the trans and then have it be the tranny that keeps me from going...

 

[nvrstuk]

Is this the straight scoop?

"The solenoids control whether the trans is in 1,2,3,or 4 when the shifter is OD. They do not control whether it is in P, R, N, D, 2, or 1. That is controlled by a valve connected to the shift cable. "

 

[Viperwolf1]

Nothing electrical can cause a lack of reverse in a 4R70W. It's only controlled by the position of the manual shift valve. So either the shifter adjustment is off or you have internal problems.

 

[nvrstuk]

Thanks...


That plus the fact that no matter where the shifter is...the rig still wants to go forward...sure sounds internal...

Can solenoids cause no reverse and ONLY forward in all shifter locations? Or only if the sun gear/clutch pack is toast...?

 

[Viperwolf1]

Is this the straight scoop?

"The solenoids control whether the trans is in 1,2,3,or 4 when the shifter is OD. They do not control whether it is in P, R, N, D, 2, or 1. That is controlled by a valve connected to the shift cable. "

Not exactly. The solenoids control the gears in OD, D and (I think) manual 2. Only P, R, N, and manual 1 are hydraulically controlled.

 

[Viperwolf1]

Thanks...


That plus the fact that no matter where the shifter is...the rig still wants to go forward...sure sounds internal...

Can solenoids cause no reverse and ONLY forward in all shifter locations? Or only if the sun gear/clutch pack is toast...?

Solenoids can't cause no reverse and they can't cause forward in all positions.

 

[nvrstuk]

OK, I'll pull the pan in the am for a last ditch what could possibly happen with the shift rod...really doubt it will be that easy 'cause I can't see how it could messed up and not allow reverse and even more...how could it allow Park to be "in gear"?

Thanks for the input.

 

[Viperwolf1]

OK, I'll pull the pan in the am for a last ditch what could possibly happen with the shift rod...really doubt it will be that easy 'cause I can't see how it could messed up and not allow reverse and even more...how could it allow Park to be "in gear"?

Thanks for the input.

I would think the forward clutch must have welded itself together to get binding in park.

 

[Broncobowsher]

Yeah, not great timing huh!!

In Park you can feel the engine load up...like power braking but probably working against the park pawl...

I pulled the fuse to the Baumann so I would be in limp mode and the symptoms are the same.

I checked the movement of the MLPS and the movement of the shift rod going into the tranny and they both seem ok, but I did not remove and re-install.

You have a clutch applied when it shouldn't. Rules out the electronics as well.
As mentioned it could be a welded clutch.
But it could also be a stuck valve in the valve body. Or a blown separator gasket.

On the right side of the case there are some test ports. One should be labeled FWD, the forward clutch. Put a pressure gauge on it (500 PSI as transmission pressures are often in the 300+ range) and start the engine. IF you are getting pressure on that port, the clutch is hydraulicly coupled. I would look at the valve body. If you don't have pressure, you need a rebuild.

 

[nvrstuk]

Thanks for the troubleshooting tips.

I'll slap a gauge on that port this am....

Check the pressure when in "Park", correct?

Think I'll have someone with their foot on the brake when I'm underneath reading the gauge...

 

[Viperwolf1]

Check pressures in all the positions.

 

[nvrstuk]

Glad I had my BPT adapter... forgot it wasn't NPT.

Thanks, I'll have someone with their foot on the BRAKE run it thru the gears and record the #'s.

Thanks for posting the numbers! I had a 0-400# gauge out first then thought at idle I'd only need a 0-200.... after viewing the chart I'll dig out a 0-100# gauge...

My kids will be able to retire after cleaning out my barn and shop with a month long garage sale when I'm gone!

 

[nvrstuk]

You have a clutch applied when it shouldn't. Rules out the electronics as well.
As mentioned it could be a welded clutch.
But it could also be a stuck valve in the valve body. Or a blown separator gasket.

On the right side of the case there are some test ports. One should be labeled FWD, the forward clutch. Put a pressure gauge on it (500 PSI as transmission pressures are often in the 300+ range) and start the engine. IF you are getting pressure on that port, the clutch is hydraulicly coupled. I would look at the valve body. If you don't have pressure, you need a rebuild.

SO I re-read this and I"m having trouble understanding it. IF I have pressure at the FWD port the clutches are hydr. locked and I'm pulling it for a rebuild.

IF I don't have pressure there I need to pull it and rebuild...

??? What did I miss here...I got a good nights sleep since I didn't work on my rig till 1am like every other night... lol

I'm heading out right as I was looking for an 1/8" street elbow...

 

[garberz]

SO I re-read this and I"m having trouble understanding it. IF I have pressure at the FWD port the clutches are hydr. locked and I'm pulling it for a rebuild.

IF I don't have pressure there I need to pull it and rebuild...

??? What did I miss here...I got a good nights sleep since I didn't work on my rig till 1am like every other night... lol

I'm heading out right as I was looking for an 1/8" street elbow...

If you have pressure the clutches are good, you probably have a valve body issue. If there's no pressure, your clutches are welded together, you'll need to pull it for a rebuild.

That's the way it reads to me.

Mark