Truck stuck in 3rd gear limp mode

[Turbo Terry]

1999 dodge Cummins 2500  truck has 168k with a DDT tranny installed about 120k  miles ago . It has a smart controller installed to keep the torque converter locked up for the BD exhaust brake to slow me down while hauling my slide in camper . Third / forth gear lockup at 50 mph kicks out at 30 mph.  275 hp Rv injectors and edge  set on high about 300 hp. Tranny built for this much horsepower. This my set up.  10 amp fuse in PDF blows when key is turned on.  Has code p0753.  Relay is good  horn test.  And pin 21 on the PCM READS 33.3 OHMS. Pan has not been down yet.  I need good advice on what to do next ?

[Turbo Terry]

Okay.  Help me please.  My 10 amp  fuse was blown when I checked out my truck. My question is does a governor pressure solenoid or transducer gone bad can it blow the fuse or is it the wiring. Will the fuse blow if they are bad. No truck.  Lifes not good thanks

[Mopar1973Man]

Well first thing I would do is peek at the wiring diagrams in the article section. Now I would ohm test between end to end. If a wire is shorted to ground it will show zero ohm between the body and a open wire. Might have to pull the pan and test the internal wiring inside the transmission.

[Turbo Terry]

Thanks for the reply I just reviewed the wiring diagram. 71 yrs old and hip replacement and both knees makes my under truck creeper days over. Finding it very hard to find a transmission shop that will look at this problem. This week end I plan on having my step son unplug the wiring from the transmission give it a good cleaning and inspection the try the key on and see if the fuse blows .  At this time we will try to ohm out the wires best we can. I guess through the relay terminal but I’m not sure about this . I can’t drain and drop the pan yet.  I have a May 28 th schedule with another transmission shop  This will be number 3  and they are all backed up on their work employee shortages etc who knows. The pandemic has effected much of this. If the shop won’t can’t work on it stepson will drain and drop the pan and and replace the gov pressure solenoid and transducer . New filter gasket  and fluid and I might be good to go if the wirings not bad. I have changed all these parts years ago etc it’s not hard but messy a bit . Anyway back to the wiring .can I buy new wiring for this truck?   Or is it a find  the shorted burned up wiring cut it out type thing etc. Has anybody found a replacement wiring and just changed it out. And how hard was that? That’s where I’m at right now thanks for any help .

Is this what I need to repair the transmission end?

 

https://cobratransmission.com/repair-kit-harness-solenoid-a618-47rh-47re-48re-205069-1

 

Is this what I need to repair the transmission end?

 

https://cobratransmission.com/repair-kit-harness-solenoid-a618-47rh-47re-48re-205069-1

 

I would think it would be the end that comes out of the firewall to the transmission that would be bad. Most likely the connector. Maybe just oily and dirty and shorting out ?? 

[wil440]

Copied from elsewhere

 

P0753 DODGE Possible Causes

 

Low transmission fluid level

Dirty transmission fluid

Faulty shift solenoid valve

Shift solenoid valve harness or connectors

Shift solenoid valve circuit is open or shorted

 

I've been diagnosing heavy plant faults for over 40 years, worked for Caterpillar, Finning UK (the Cat dealer here) field service and several quarries and here's a tip directly from Caterpillar.....  follow the diagnostic procedure to the letter for the code you are working on and never deviate.... you will find the fault sooner or later and get there with the minimum parts used.

Now on the list above IF the fluid level and condition is good and a look over wiring, I'd be onto number 3 and drop the pan unless ohm checking the external wiring is really easy and quick

Also lists like above are usually written in probability order if from a good source

 

 

 

 

[W-T]

@Turbo Terry your post states

 

On 5/9/2021 at 11:33 AM, Turbo Terry said:

 10 amp fuse in PDF blows when key is turned on

 

I assume this 10 Amp fuse is in the PDC (power distribution center) (PDF ?) please tell me what fuse you're specifically identifying?

 

I apologize as I no longer am in possession of the Factory Service manual however; I do know Mike Nelson has certain documents available for review and I'll do a little homework on this in order to help you.

 

First of all, having a 10 Amp fuse open immediately when the key is "turned on" is very alarming regardless of "what" circuit is being supplied by this fuse. Please help me here.

 

P0753-Trans 3-4 Shift Sol/Trans Relay Circuit

On 5/9/2021 at 11:33 AM, Turbo Terry said:

 Has code p0753.

On 5/9/2021 at 11:33 AM, Turbo Terry said:

 Relay is good  horn test

I need you to clarify your observation here..."relay good" and "horn test"??? The CODE PO753 is specific to your transmission only.

 

I will go out on a "hunch" here and it is not my normal way of doing so however;

 

This "wire harness and plug" you've brought into the subject matter...if this plug goes directly onto the 47RE please unplug it, replace your 10 Amp fuse and turn your key to the on position and report back on the status of this fuse. I am ONLY guessing here on your behalf but, if the fuse "does not open" in this TEST, it will verify the wire structure that feeds the solenoid/relay within the 47RE is sound and you have NO extraneous connections (short) to ground.

 

This, then leaves, the actual device within the transmission (solenoid/relay) as the actual DC load that would have a specific but, intrinsic DC resistance that is NOT a direct path to ground.

 

@wil440has brought this data forward and is very valuable in this analysis.

13 hours ago, wil440 said:

Faulty shift solenoid valve

Shift solenoid valve harness or connectors

 

  If for some unknown reason this solenoid/relay device, within the transmission, has "lost" it's structural integrity and is allowing 12 volts DC to be conducted directly to ground (a simple short) this would be the ALARMING REASON for opening a 10 Amp protective fuse within your Power Distribution Center (PDC).

 

@wil440 also included the final line of trouble shooting data...

13 hours ago, wil440 said:

Shift solenoid valve circuit is open or shorted

 

Please NOTE: We know by your statement that a 10 Amp fuse is opening when DC current is applied (key turned on) so...this would be a "short" within the body of the solenoid structure and NOT an "open" where you would have NO current flow.

 

I hope this helps in focusing in on your task...sorry to give you homework but, it will help as you proceed in analysis.

 

OH...I must kid around with you just a little...I'm curious about the horn test

 

Cheers my Friend,

W-T

[dripley]

@W-TThe horn test is just checking to see if a given relay is bad.  If the horn honks we know that relay is good and beings the relays are the same I would just swap it for a questionable relay and see if it made any difference. If the horn still works I would now the relay is fine and the relay is not the problem.

[W-T]

@dripley I didn't know this was involved in the circuit and you just taught me something. I was focused on the 10 Amp fuse and the peripheral circuit only because I didn't review the actual current flow. I must say thanks, and I hope the information assists Turbo Terry.

 

I'm regretful having lost my Factory Service manuals and I feel I'm flying blind...it is curious that a relay is in series with this solenoid and a 10 Amp fuse would be down stream of the relay contacts...I'll stop guessing how this circuit is providing current to the solenoid and refer to the schematic.

 

Dripley, you schooled me...thank you

[dripley]

Thanks, this is a red letter day for me. I know nothing about the circuit either. I just know I have swapped relays on mine just to eliminate it as the problem. There are FSM's in the articles section you can down load for different model years of the 2nd gen and maybe the 3rd gen too. Thats how I got mine.  

[Turbo Terry]

Thanks gents.  Wire test tomorrow and clean the connector etc and inspect. Will report back ASAP. 

[Mopar1973Man]

@W-T all FSMs are in the download area. You are correct if the fuse is blowing instantly there is wire shorted to ground.

 

@Turbo Terry check the 99 wire map.

 

Edited May 14, 2021 by Mopar1973Man

[Turbo Terry]

I ordered a 12445bk repair kit harnes (solenoid) 47 Re. It’s the plug and wires to splice on the end.   I’m hoping the connector is bad.  Or maybe just very oily and dirty ?

[Turbo Terry]

Ok we unplugged the big plug on the driver side 8 wire square with round center. Very dirty but not broken.  Cleaned it up as good as possible. Left it unplugged new 10 amp fuse key on.  Fuse did not blow.  Plug it back in key on fuse blew.  Picture using round mirror

So what’s next? Drop the pan and change the transducer and solenoid I would suppose. Is there anyway to access the part of the plug inside the tranny?

IMG_9630.HEIC.heif IMG_9627.HEIC.heif

So what’s next? Drop the pan and change the transducer and solenoid I would suppose. Is there anyway to access the part of the plug inside the tranny?

[Mopar1973Man]

Short is in the transmission. Time to pull the pan.

[W-T]

OK @Turbo Terry good job in procedure and this certainly narrows the focus to the suspected solenoid being at fault. Previously, you mentioned purchasing an additional wire harness that has this multi-pin connector, and being you have now verified the actual component, I hope you're able to recoup the expenditure. and obtain the solenoid.

 

Why this solenoid failed is unknown however; perhaps @Dynamic would have incite as to what may have contributed to this condition. Of course knowing where this device is located and knowing this is a quasi hostile environment brings several possibility's to consider.

 

Being that this 47RE was prepared by DTT I'll assume Bill Kondolay's procedure is a sound application in regard to keeping 3rd and 4th gear lockup electrically coherent in the scheme of reliability and longevity. I am not questioning the integrity of DTT's procedure...the failure of this solenoid in a wet hydraulic pressurized, high temperature environment could and can lead to sporadic abnormalities if internal pressure seals fail and allow hydraulic fluid laden with micro conductive metal particulates to cause an undesired electrical current path...hence, a blown fuse.

 

I do see your photos with contamination of the critical multi-pin plug...may I suggest the use of WD-40 in an aerosol can to liquid-purge the small pin area and compressed air to fully clean the electrical working surfaces prior to reinstalling the plug to your new solenoid application. 

 

WD-40 is an excellent product for such purposes, keeping in mind it is a flammable liquid solvent in nature so...compressed air is required to alleviate any puddles of liquid hiding in small crevasses prior to electrical current applications.

 

You did very well in this task...please let us know of your final outcome.

 

Cheers              

 

 

[Turbo Terry]

Yes the pan needs to come down next. Thanks for the wiring diagrams also.  My stepson ( my creeper man )  and I got pretty excited we thought the gunk and dirt etc was the problem but it was not. I have a Mag Hytec  pan with drain so it makes it a bit easier. I have changed the fluid and filter many times over the years but knees and hip makes this impossible now. Might be time for a new truck and let Dodge do the servicing.  I can’t really expect stepson to change oil etc etc   He has a job and kids.  But I still have to repair it to sell it.  I know we can change out the transducer and the solenoid but the valve body and inside wiring this  where I have to draw the line on my skill level. You have to know your limits.  It’s scheduled to go to the shop in 10 days. First shop would not work on it said they didn’t do electrical second shop truck was to old so we shall see with three. Is there really any point in thinking this is a transducer or solenoid problem at this point. I got 33.3 ohms on pin 21 on the pcm which is good. Hard to figure out how the wiring shorted out on the inside in my mind. More later and thanks to all for the help.

[Mopar1973Man]

Test the power lead pin to ground on ohms of the DVM.

[Turbo Terry]

We no longer have the 8 position plug disconnected and I have no way to access it sorry

[wil440]

as I said at the beginning IF wireing looks to be ok on a visual drop the pan and check solenoids, if you have disconnected the trans plug at the trans and the fuse does not blow then it is inside the trans and everything electrical is doable with the pan dropped, something in there or even wiring will be shorted to earth..... ground where you are 

[W-T]

Turbo Terry,

 

I'm sorry for the poor response from from various automotive repair facilities. Fully accredited shops are certainly difficult to find these days and electrical issues are unfortunately being met by less than qualified individuals in an increasingly sophisticated electronic arena.

 

You have successfully found the component that is sinking excessive current and opening the protective fuse. The solenoid is the bad component.

 

@Mopar1973Man has directed you towards the next step of dropping the pan to gain access to this solenoid.

 

Your observation of Pin 21 at the PCM being 33 ohms is not focused relevance. That DC resistance being measured against ground with your DVM is the intrinsic DC resistance of the internal circuit of the PCM. It is likely this output never sees direct ground because it is connected to another component in series and it too has lumped DC resistance and in a series DC circuit, resistance would add and of course increase resistance.

 

a simple example would be expressed in Ohm's Law of  I=E/R 

 

a basic resting voltage of 12.6 volts

 

so... 12.6 divided by 33.3 ohms = .378 millamps

 

In power we would see it as P=E*I    or power = Volts x Current

 

so... 12.6 x .378 (mills) = 4.76 watts

 

this is a very small amount of power being dissipated to ground...let's just call it around 1/3 amp

 

NOW...your analysis reveals a very different set of values in the equation.

 

Ohms Law for Power is  P=E*I

 

so 12.6 (volts) x 10 (amps) (your 10 amp fuse) = 126 watts  HOLY COW !!!!

 

This reveals your RESISTANCE of the solenoids internal resistance.

 

Ohms Law R = E/I  or resistance = voltage divided by current (amps)

 

so 12.6 (volts) divided by 10 (amps) = 1.26 Ohms  HOLY COW !!!!

 

This resistance is almost becoming a perfect conductor with a very small resistance. A good piece of copper wire has very little resistance.

 

You have already found the answer to your question, the question in your mind of "how can the (wires) short together"...it is NOT the wires it is the integrity of the solenoid's internal structure allowing a (short) pathway to ground.

 

Your own research, your own two hands, and following the procedure has uncovered the faulty component in your DC circuit.

 

 By the way, you should instruct your selected repair facility on how to diagnose this and become a better shop...you Sir, are a better technician then they are !

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited May 16, 2021 by W-T
spelling