Trans won't shift out off 1st gear.Nag 1

05highroof

New member
On my way home yesterday when engine light popped up on the dash. Truck will now not shift out of 2nd gear.When in drive (D) I'm also unable to shift or change gear selection indicator on the dash. (it stays in drive even if I try and shift through the gears manually) Still waiting on my DAD unit but I plugged my generic code reader in and it came up with the below trouble code. Any ideas???
 
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rlent

New member
That's the same symptoms and code I had - it is potentially indicative of an issue with one of the (2) internal speed sensors in the transmission.

You should have the codes read by either a DRB III or DAD as there may be more info than is available with a generic code reader.

I solved the issue by replacing the plastic connector plate (under $190 from Berry Dodge in Corsicana, TX) on top of the valvebody, which contains the speed sensors ...... although it might have been possible to resolve it by just cleaning the connector plate of ferrous metal debris. To understand the issue and some of it's possible causes read the following thread (my posts are near the end):

Dr. A's NAG1 Tech Alert
 

05highroof

New member
Thanks for your response. It sounds like I have the same problem that you had. Although my sprinter didn't go into limp home mode because my turbo would still spool up.(doesn't LHM disable the turbo?)
I've done the trans service recommended by Doctor A (50k ago)but I guess it's time to take a look see into the Nag 1 again. This time should go faster since I've already done this once.
 

220629

Well-known member
...
Although my sprinter didn't go into limp home mode because my turbo would still spool up.(doesn't LHM disable the turbo?)

...
I would agree one of the common indications that you are in LHM limp home mode is the turbo being held out. That said, there are different levels of LHM, so you could still possibly be in a computer set LHM. I've learned that the ECM engine control module (aka ECU) can set LHM and so can the TCM transmission control module. If the TCM sets the LHM it very well may not hold out the turbo. Once you are locked into a gear that may satisfy the TCM that you can do no more damage?

That is a guess. Why oh why don't they include an LHM light on the dash?? It would make things so much more obvious.

Maybe Doktor A, Sprintguy, or other professional can add more facts. vic
 

abittenbinder

Doktor A (864-623-9110)
Thanks for your response. It sounds like I have the same problem that you had. Although my sprinter didn't go into limp home mode because my turbo would still spool up.(doesn't LHM disable the turbo?)
I've done the trans service recommended by Doctor A (50k ago)but I guess it's time to take a look see into the Nag 1 again. This time should go faster since I've already done this once.
One of the LHMs the TCM can set, shuts off all power to the valve body's circuit board. This leaves you with only 2nd gear and reverse operation. I suspect your LHM episode defaulted you to 2nd gear, not 1st.

If you find your DTC is indeed indicating problems with a speed sensor circuit, please note the word CIRCUIT. This can involve connections and wiring between the TCM and the circuit board location of the speed sensors. Doktor A
 

05highroof

New member
One of the LHMs the TCM can set, shuts off all power to the valve body's circuit board. This leaves you with only 2nd gear and reverse operation. I suspect your LHM episode defaulted you to 2nd gear, not 1st.
Yes I believe it is stuck in 2nd gear not 1st. That makes sense.That would explain the lag in acceleration from a complete stop.
Thanks for the
tip Doctor A, I assume you mean check plug connections before looking inside the trans. One thing that comes to mind and it my be irrelevant but right before the light came on I was leaving a parking lot and had driven through a large pot hole filled with water.Hmmmm:thinking:
 

05highroof

New member
Dropped the pan today and went though Doktor A's trans tech alert trans service. It's been 38000 miles since the last trans service. This time there was more sludge on the drain pan magnet then when the trans was serviced @148000.
The circuit board on the valve body had some build up near were the sensors make contact but it easily cleaned off with some contact cleaner. Reassembled and added fluid. Cleared code. Problem still there.

Could the speed sensors be at fault?? Any ideas?? What should / could I do next?
What could the DAD unit do to help trouble shoot this problem?
 

05highroof

New member
Just thought of something after looking in the service manual. I cleared the dash light using my OBDll scan tool.
The manual says to clear it using DRB3 tool. Would this make a difference?
 

220629

Well-known member
...

The manual says to clear it using DRB3 tool. Would this make a difference?
It may very well need a DRBIII or DAD to get back to normal even if you cured the problem. I know OBDII resets don't do it all on a Sprinter.

The text below is part way through post #1. The bold about dealer reset is mine.

LHM limp home mode possible causes
https://sprinter-source.com/forums/showthread.php?t=7173

Transmission Sensor Readings (whether an actual physical condition or faulty sensor reading)
From Andy Bittenbinder:
Limp home mode is typically triggered by overspeed indications from
the internal transmission input speed sensors, engine overspeed or
improper gear ratio faults. You will likely find TCM DTCs related to
these faults. Cause can be electrical, control unit or transmission
related. Doktor A
More from Andy Bittenbinder:
The TCM(transmission control module) is able to signal the illumination of
a MIL(malfunction indicator lamp)which we see in the instrument
cluster as the small engine/trans(drivetrain) pictogragh. It does this
by communicating with the ECU(engine control unit) to trigger that
lamp. The TCM stores its own failure codes(DTCs) which can then be
accessed by technicians. It can recognize many misc. elect. problems
and some hydraulic problems.
First a few words regarding limp-home/shut down modes. Some (minor)
DTCs(failure codes) will allow the trans to resume business as usual
when problems go away on their own. More serious anomalies will shut
down all the internal solenoids and default to whatever gear you
happen to be in at the time. After you cycle the ign. key (or shift
into park) it will then go into a limp-home mode which is (usually)
2nd gear and reverse and a shut off of the TCC(torque converter
clutch). Typically a max. of about 3 cycles of the key will allow a
"temporary reset" to quasi-normal operation and after that, limp-home
will be permanent until the dealer clears the codes.
(Bold here is mine. vic)Some failures
will not shut down all internal control solenoids. If internal
slippage is detected it may default to 3rd gear operation(in
limp-home). The transmission can even become totally disabled by
defaulting to neutral(!). Engine overrev could trigger that mode.
How does the TCM know when fluid levels are low? Or more
importantly, low enough to cause possible damage? The TCM monitors the
speed of the 2 internal drive elements. It also monitors output
shaft speed(I seem to recall it has no dedicated sensor for this
funtion but uses ABS or some other external signal). Anyway, by
monitoring these rotational speeds it can recognize (and calculate)
SLIPPAGE. In 2nd, 3rd, and 4th, for instance, the elements should be
spinning at same speeds. It probably will recognize it before you can
and then trigger the MIL and limp-home. Permanent damage then depends
on how far you drive under these conditions. Moral of the story-If
driving and engine-trans MIL lights and limp symptoms appear-STOP and
at least look inside/underneath for signs of the obvious-such as
leakage. Carry a trans dipstick and extra fluid if you're prone to
driving far from civilization. Oh, and a postscript-just to complicate
things- not all limp-homes of 2nd gear and reverse involve
transmission anomalies! For instance a failure of communication
between control units (via the CAN bus) will trigger that same
limp-home. If the TCM can't talk to the ABS control unit your going
home in 2nd gear(that is-after those 3 ign. key cycles). Andy
*****

Good luck. vic
 
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05highroof

New member
That's good information,although confusing when it come to solving my problem. Seems without proper diagnostic equipment I'm really guessing at what the problem is. :thinking:
 

220629

Well-known member
...Seems without proper diagnostic equipment I'm really guessing at what the problem is. :thinking:
05HR,
I believe that is the unfortunate truth and is exactly why I purchased a DAD even though I have access (sometimes limited) to a DRBIII with Sprinter card and cable through a good friend, a very good friend actually. vic
 

05highroof

New member
After re-reading some of the posts,in particular the part about cycling the key to get normal operation again it dawned on me that I've had this problem before and that it reset after cycling the key.Once a few months ago I was about 1/2 mile from my house and I noticed the truck seemed to be stuck in a high gear and the shifter was disabled of forward gear selection. After pulling into my drive I turned the truck off and then back on and all was fine.This happened one other time. No check engine light.My sprinter was trying to tell me something and I didn't listen.:bash:
 

220629

Well-known member
...My sprinter was trying to tell me something and I didn't listen.:bash:
05HR,
Don't be too hard on yourself. I don't think it is as easy as just reading and understanding for novices like us.

I have been going back over my LHM, DTC Codes, Stoopid Things, etc. threads to edit them, try to correct inaccuracies, and try to update them with any new stuff we have learned.

As an example, when I read through the LHM thread I realized that if had I really read and comprehended all the stuff I would have realized that both the ECM and TCM can set Limp Home Mode and I would have had an idea of the different levels that can be set. Doktor A had explained it well in different posts. It's easier under the guidance of professionals. I think it took a reminder from him in a post to actually get me thinking that way. I find that I learn much more when I'm reading to resolve something than when I just read through more casually.

I hope you get your DAD soon. I really need to get out and play with mine more often except that this one doesn't catch a ball very well. vic
 

05highroof

New member
05HR,
Don't be too hard on yourself. I don't think it is as easy as just reading and understanding for novices like us.
Thanks for the encouraging words AP.

That's a very generous offer dbeyer! I see you've sent me a PM. I will try and contact you direct. thanks!
 

rlent

New member
Dropped the pan today and went though Doktor A's trans tech alert trans service. It's been 38000 miles since the last trans service. This time there was more sludge on the drain pan magnet then when the trans was serviced @148000.
You cleaned the pan magnet off at 148K correct ?

The circuit board on the valve body had some build up near were the sensors make contact but it easily cleaned off with some contact cleaner.
Did you remove the connector plate from the valvebody ?

If not, were you able to examine the bottom side of the speed sensors (the side facing the valvebody)

Reassembled and added fluid. Cleared code. Problem still there.
I shouldn't have been so lazy when I first replied - and should have enumerated the procedure that Doktor A suggested I follow when troubleshooting this problem - as I recall there were at least three potential sources of the problem:

1. Wiring
2. The connector plate, containing the speed sensors
3. The TCM itself

To troubleshoot No. 1 you must check the integrity of the wiring that runs from the TCM to the transmission - both for continuity (not broken) and for being shorted to ground.

Continuity can be checked by disconnecting the wiring connectors at both the TCM and the transmission (make sure you disconnect the ground at the battery first) and then checking that none of the wires are broken by attempting to complete a circuit on each wire by using a multimeter (set to measure resistance) or a continuity tester in between the end of the wire at the TCM end and the other end of the wire at the transmission connector end. Flexing the wiring harness as you are doing this may help isolate an intermittent break.

To check for shorts to ground, ideally (I would think) you would check each wire, at each end (all wires at one end first, then check all wires at the other end) by attempting to make a circuit from one wire to a grounded surface on the vehicle (the seat base and components in it, including the brackets that the TCM is bolted to, should be grounded)

Replacing the TCM isn't as simple as just slapping a new one in there - it requires a DRB III (or DAD ?) and the TCM must be coded or initialized to the vehicle.

Could the speed sensors be at fault??
Apparently mine were.

Any ideas?? What should / could I do next?
See above.
 
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rlent

New member
After re-reading some of the posts,in particular the part about cycling the key to get normal operation again it dawned on me that I've had this problem before and that it reset after cycling the key.
Once a few months ago I was about 1/2 mile from my house and I noticed the truck seemed to be stuck in a high gear and the shifter was disabled of forward gear selection. After pulling into my drive I turned the truck off and then back on and all was fine.This happened one other time. No check engine light.My sprinter was trying to tell me something and I didn't listen.:bash:
Yup - mine did the same thing :smilewink:

BTW, it if turns out to be the TCM, lemme know - I have a brand new, unused and uncoded TCM (for at least an '06, possibly other years as well) that I bought - just in case that was it, rather than the connector plate - that I could hook ya up with for a very good price (depending on what year yours is)
 

05highroof

New member
Thanks for the reply / info rlent. At 148k I did remove the valve body but did not remove the circuit board from the valve body.I did remove the six solenoids just to see what was inside but that was it. There was very little dirt / build up to be seen so I didn't see the need to go further. Furthermore I wasn't having any problems at the time so that made the decision easy.This time there was a noticeable buildup of sediment / sludge so I took it all apart and cleaned it.

But I have good news! dbeyer came over today with his DAD unit and cleared the code and all is back to normal.
I've driven about 30 miles so far and all is well. Did I fix the problem? I guess time will tell.

For the record I was able to turn the check engine light off with my OBDII scan tool but it did not clear everything / return the trans back to normal service.
As soon as dbeyer cleared it with his DAD all was back to normal.At least for now.
 
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rlent

New member
For the record I was able to turn the check engine light off with my OBDII scan tool but it did not clear everything / return the trans back to normal service.
Now that ya mention it :rolleyes: ...... when went into permanent LHM I was able to shut off the MIL on the dash with my OBD ...... but it would come right back after I restarted ......

I had it towed to a Dodge and they reset everything with a DRB III ..... and I was able to drive home (200 miles) ..... I replaced my connector plate/speed sensors immediately after that and have had no further problems (almost 100K + miles since) .....

But who knows - perhaps it was a fluke and just cleaning it would have done it ..... I wasn't willing to take the chance ......
 

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