E4OD won't move from stop in D

david85

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I'm trying to think of what is different when the transmission is rolling that could make such a big difference (1st gear available vs not available at standstill). I was hoping the RPM might offer a clue, but it seems that has no effect.

Maybe one of the sprags is slipping???

In my case, the center support bearing failed, which caused internal line pressure loss. This caused the transmission to struggle to produce 1st gear when starting from a standstill. Adding RPM helped for a little while until the clutches burned out.
 

SultanofNACL

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Howdy!
Ah, the woes of E4OD diagnosing.
Have you ever checked the rear brakes to see if there is anything hanging up or dragging severely? I had symptoms very similar to what you are experiencing and could not make any heads or tails of it, but after having the truck down for other repairs I decided to rebuild the rear brakes. All new parts and shoes, properly adjusted shoes, and brake grease greased contact points and the truck rolled when transmission was placed in drive with foot of the service brake pedal.
 

1189-66

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Old thread for this type of problem, but I just installed a shift kit on my 1990 E4OD. The valve body gaskets had gotten so brittle over the years, that they had crumbled in a few spots. Aside from the improved performance of the shift kit, I think that new gaskets also made a difference.
 

david85

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Brittle valve body gasket can be an indicator that the transmission has overheated at some point.
 
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XOLATEM

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Maybe one of the sprags is slipping???
Reverse sprag could be an issue. I would take a look in the valve body first.There could be a hung or stick valve

Other than what has already been suggested and since I have not tested it out to feel first hand what is really happening here...I hesitate to offer any suggestions at this point...the codes need to be pulled and it would be great to hook up the diagnostic tool that I mentioned in a previous E4OD thread...

But I do want to offer up some insight into the mechanical powerflow that these two guys have touched upon...

On the low-reverse roller clutch in the back of the unit...the inner race is bolted to the case...it locks and holds for forward range in 'D' and then freewheels after that...in reverse and manual forward in '1' it is overridden by the low-reverse clutch pack that is splined to the case.

It is a spring and roller affair that can slip if the springs that force the rollers against the ramps on the outer race become weakened....rare for that to happen...it usually is a fairly reliable component for a least the first rebuild...

The other component is the overdrive sprag...now THAT one can slip and not hold for various reasons...especially if you put the selector in 'D' and not try a manual range first...on that one the ramps that bind the two races are on the elements and they tilt in unison and lock two smooth races....the elements are all triggered to lock by a 'tickler' spring and that spring can get weak or deformed from hard use....fluid quality can affect the operation...surface friction on the races...wear on the elements...etc, etc,...

The OD sprag holds in 'D' range on takeoff and is assisted by the overrun clutch in the manual ranges...and the OD sprag has to freewheel in overdrive operation...the overrun clutch has to release in overdrive operation...so...that is how it works.

Now...on the 'neutral safety switch'...that is only one of its functions...

It is actually called an MLPS...manual lever position sensor...it is fed 5 VDC and has a set of resistors...and whenever I tested them the readings were seperated by about .7 of a volt...you start out around .7 VDC at manual low range and each click up increases the signal return to the ECM by approx .7VDC...untill you get to around 4.5 or almost 5 VDC.

A problem with that unit will cause the ECM to not know WTHeck the driver wants to do and the ECM will not command the right line pressure to hold the clutches against the torque of the engine and the weight of the vehicle. It needs reference voltage, proper adjustment, good ground, and no slop in the linkage as some here have noted...

A couple of or three months ago one of the posters here...who did not claim to be a mechanic BUT was a good electronics tech had looked up and identified and posted a list of the sensors that affect the operation of an E4OD...it would be good to add that to the reference section so everybody can see what is needed and what has to be sensed and why on these units...it would speed up any diagnosis and questions about these things when they act up.
OD OFF light dimly lit? If so check the TCM for power. The tranny is trying to start in a higher gear. Most of the time its a failed TCM relay.
This is the first thing I thought of too....because the unit will go to limp and will not start off in 1th...(haha)...in 'D' range...(1st...seriously)....

I could comment on more...but I gotta get rolling...hope this helps and good luck on it all...

Have a good day, Y'all....
 

mdev

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In my case, the center support bearing failed, which caused internal line pressure loss. This caused the transmission to struggle to produce 1st gear when starting from a standstill. Adding RPM helped for a little while until the clutches burned out.
@david85 you mention your tranny struggling to produce first gear from a dead stop. My 1990 7.3 e4od is having the same issue, along with revving too high before shifting to 3rd, and often downshifting to 2nd when there's no reason to & then cycling between 2nd & 3rd. Once I hit OD speeds it seems to work fine. I've been manually shifting it (seems to work best starting in 2nd) and that temporarily solves the bigger of the two issues, but I want it fixed.

Took it to a tranny shop and the owner said the transmission seemed relatively good. He replaced a sensor on the trans (I think MLPS?) and recommended I replace the FIPL because he got code 23 (they apparently only work on the trans itself, not related sensors elsewhere). Did that (& tested: currently reads 1.2v at idle/3.9v wot), but no difference. Called shop back and he said could be the solenoid pack but said something to the effect of if I wanted to go to the expense of replacing that, might as well pull the trans, then he could get a better look at if anything needs rebuilding, and either way I might want to consider upgrading with a shift kit once pulled out bc I occasionally haul heavy loads. I'm trying to avoid that expense but will do it if I need to. He seems confident that my "main" issue isn't needing a rebuild.

Other issues that might be related: Speedo needle bounces around. This was minor at first but has been getting worse, sometimes staying at 0 now for a bit, and consistently reading low. I don't care ab an accurate speed gauge, but I'm wondering if whatever is causing this issue is also giving bad info to the trans. Seems very plausible now, but I didn't think this could be it at first, mainly bc these trans issues started before the speedo was noticeably off. Also if this is the obvious problem, I don't understand how the tranny shop missed it too bc I did tell them. But maybe they missed me both saying that & during their test drive somehow. Cruise control also stopped working before the speedo was noticeably off, if that gives any clue. Don't think this matters much, but the orange indicator on the dash of the position of the column shifter doesn't align perfectly when it's fully seated in gear (indicates about half a gear off). Fluid level's good, and had a transmission flush maybe 3k miles ago.

What would you all suggest I check/replace next: VSS? Speedo cable? Or take it to a different tranny shop for a 2nd opinion?
 

david85

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@david85 you mention your tranny struggling to produce first gear from a dead stop. My 1990 7.3 e4od is having the same issue, along with revving too high before shifting to 3rd, and often downshifting to 2nd when there's no reason to & then cycling between 2nd & 3rd. Once I hit OD speeds it seems to work fine. I've been manually shifting it (seems to work best starting in 2nd) and that temporarily solves the bigger of the two issues, but I want it fixed.

Took it to a tranny shop and the owner said the transmission seemed relatively good. He replaced a sensor on the trans (I think MLPS?) and recommended I replace the FIPL because he got code 23 (they apparently only work on the trans itself, not related sensors elsewhere). Did that (& tested: currently reads 1.2v at idle/3.9v wot), but no difference. Called shop back and he said could be the solenoid pack but said something to the effect of if I wanted to go to the expense of replacing that, might as well pull the trans, then he could get a better look at if anything needs rebuilding, and either way I might want to consider upgrading with a shift kit once pulled out bc I occasionally haul heavy loads. I'm trying to avoid that expense but will do it if I need to. He seems confident that my "main" issue isn't needing a rebuild.

Other issues that might be related: Speedo needle bounces around. This was minor at first but has been getting worse, sometimes staying at 0 now for a bit, and consistently reading low. I don't care ab an accurate speed gauge, but I'm wondering if whatever is causing this issue is also giving bad info to the trans. Seems very plausible now, but I didn't think this could be it at first, mainly bc these trans issues started before the speedo was noticeably off. Also if this is the obvious problem, I don't understand how the tranny shop missed it too bc I did tell them. But maybe they missed me both saying that & during their test drive somehow. Cruise control also stopped working before the speedo was noticeably off, if that gives any clue. Don't think this matters much, but the orange indicator on the dash of the position of the column shifter doesn't align perfectly when it's fully seated in gear (indicates about half a gear off). Fluid level's good, and had a transmission flush maybe 3k miles ago.

What would you all suggest I check/replace next: VSS? Speedo cable? Or take it to a different tranny shop for a 2nd opinion?
Hello, and welcome.

I would take a closer look at the VSS, and the drive gear on the end of it. If the speedometer stopped working on a Pre 1992 truck, it means the cable physically stopped spinning (later ones are fully electronic). It could simply be that the speedometer gear has shredded (they're made of nylon and cheap to replace). Electronically, they are fairly robust and don't usually fail, but the mechanical cable and plastic gears can wear out.

Did the problems start before, or after the fluid flush?

Problems with the shift solenoids generally cause loss of certain gears. Valve body issues can cause skip shifting as well though.

The chart below shows what you can expect based on solenoid behavior.

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mdev

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Thanks for the quick response. The problems started well after the flush. I'll check that gear as soon as I get a chance in the next couple days. Is it easy to access? I'm presuming attached to the diff?
 

david85

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Your truck will have two speed sensors (again, for anyone else reading this, 1992 up is different):
1. on the rear differential. This is for your rear antilock brakes and is not related to the transmission or cruise control.

2. at the tailshaft of the transmission (or transfer case, if 4wd). This is the one you want to check.

It's held in by a steel clamp and 11mm bolt. 7/16 works fine as well if a 11 mm socket isn't available. You will see the speedometer cable going into it, plus a 2-wire harness. Usually there's enough room to slide the sensor out without unplugging the cable or the wires.

However if you have to, both can be unplugged. The electrical plug has a couple tangs, one on either side...assuming someone hasn't already broken them off. The speedometer cable should pop out fairly easily by pulling straight out, with a little sideways wiggling. The cable is retained by a stainless steel wire retainer that should allow the cable to pop out or snap back in (almost looks like a cotter pin that goes through the cable socket of the VSS sensor).

Clean the area around the sensor first, to prevent dirt from falling inside.

This video shows where to find it (yours won't have the sensor on top, only at the rear):
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