47re No Overdrive (I know, I’m sorry) - Dodge Cummins Diesel Forum
94-98 Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission Ect...NO ADVERTISING

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post #1 of 27 (permalink) Old 04-14-2019, 03:44 PM Thread Starter
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Hi,

I’m new to posting in this form but have read a lot through here so thank you all; y’all have helped a lot already.

I know this topic has been exhausted extensively on this forum and forums alike. I just had a few questions and would like some second opinions.

I just bought a ‘97 12 valve 4x4. It’s got 256k on it and I got it fairly cheap as I knew OD was out. The guy I bought it from said the trans was rebuilt within the year. He said he was passing a car on the highway, the truck shifted out of od and never shifted back in. The truck shifts and pulls like it should, no hesitation, no slip. OD button on dash works. Just no OD. It doesn’t try to shift into od.

I started with replacing the TPS (one on the truck was clearly bad and he had hacked a cheap potentiometer in).

When that didn’t work, I spliced into the OD solenoid wire at the PCM and ran a multimeter in the cab. It read 13 volts until about 40ish mph then dropped to less than one. From what I gather from this forum, that’s how it’s supposed to behave. I also put the volt meter to the 8 pin plug at trans and it is getting the 5 volt supply, etc, there, so no shorts. I grounded the torque converter solenoid via a wire from the PCM into the cab while in third gear and it locked up.

From this I thought the pcm must be good and it could be the od solenoid so I dropped the pan and replaced those. While in there I checked the 3-4 accumulator spring and put a multimeter to the trans temp sensor (on the governor) and it read about 998 ohms of resistance, so I assumed it was good. Of course I also replaced the filter. The old filter and pan did have a moderate about of clutch material.

Buttoned it all up and no change. So I thought I may have used the multimeter wrong or something when testing the trans temp sensor, so I got a 1000 ohm resistor and soldered it in-line at the PCM (middle plug, pin 1. Violet wire) and no luck.

So at this point I’m willing and prepared to have trans rebuilt and beefed up a bit. I just wanted to make sure I’ve exhausted all “quick fixes” as I don’t want to rebuild it and still have no od because it’s an electrical/wiring issue, and because I’m strongly considering a 5 or 6 speed swap so I don’t want to dump a bunch of cash in the 47re but I would like to be able to drive the truck while gathering parts.

So, in conclusion, my questions are~

-When trying the 1000ohm resistor trick, you do just put it in line, correct? You don’t solder one end to PCM and the other to ground, 5 volts or 12 volts or something right?

-When reading the forums, it seems like the older model trans (RH’s I assume), have easy bypasses. Like I’ve read many times about a three wire plug on the trans that they run 12 volts too the middle wire, then run the other two in cab to grounded toggle switches to have OD and TC lock up on demand. There by no chance is an easy way to bypass and have that on a 47re is there? I know grounding out the TC solenoid wire at the PCM worked for TC lock up but it didn’t work for OD.

-**One important thing I forgot to mention! The trans cooler lines are not great. In two spots on both the supply and return line theyre just rubber lines hose clamped to the old hard lines. The hard lines aren’t even flared. So a gentle pull can seperate them. So they do leak a lot, could it be that the fluid pressure get high enough at the rpm that it should shift into OD that it bleeds out so much from the cooler lines it drops pressure and won’t shift? **

-Does it seem like I did all the above correctly and interpreted everything right?

-Any other tips or tricks would be greatly appreciated.

Sorry about making such a long post about an already very discussed topic. Thank you all very much for your time!

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post #2 of 27 (permalink) Old 04-14-2019, 09:56 PM
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I've got a 96 trans with the same issue, I've checked a lot of similar stuff, and my final nail in the coffin was checking the OD test port for pressure.

Its the only one on the drivers side of the trans I believe, its a 1/8 npt plug just in front of the OD housing.

Mine only gets about 10psi. which to me means likely the OD lip seal is blown out as its not building pressure.

I would recommend testing your pressure at that port, that'll tell you if the solenoid and everything is working, which it does sound like it is.

If it ends up being your lip seal, they're cheap and if you have 1 2 and 3 just not 4th then your od direct clutch is fine so you shouldnt have to mess with the killer spring, you can remove just the od housing, replace the 2 lip seals and od housing gasket and od brake clutches without removing the rest of the trans, that's what I'm about to embark on with my 96/01 abomination.


EDIT: Also, yeah fix those cooler lines, its not fun having one blow apart when you're going down the road. I did all 1/2 flex line over barbed fittings on my 97 truck, works great, no more leaky connections and weird hard line to soft line connections that came apart repeatedly. My local auto parts store was concerned when I bought them out of ATF +4 twice in the same week.

Red Truck: 97 2500 4x4 ECLB 250k-ish, mostly stock.
Purple Truck: 01 1500 4x4 ECSB 12v Conversion, has all the 1996 3/4 ton stuff besides the body at this point.
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post #3 of 27 (permalink) Old 04-15-2019, 02:09 AM Thread Starter
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Thanks! I’ll definitely give it a try. Hopefully this will do the trick. How many PSI does a healthy od port read? And yeah keeping it full of atf ain’t cheap!

Edit: Found it! 5-10 psi at anytime in drive and 80-130psi when trying to shift. And according to the same thread, grounding the solid brown wire at the pcm should through it into od.

Source:

https://www.google.com/amp/s/www.cum...e.html%3famp=1
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post #4 of 27 (permalink) Old 04-15-2019, 03:33 PM Thread Starter
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What type of gauge did you get? I asked at the parts store and they said they’d never heard of anyone testing the pressure in a transmission.
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post #5 of 27 (permalink) Old 04-15-2019, 05:43 PM
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What type of gauge did you get? I asked at the parts store and they said they’d never heard of anyone testing the pressure in a transmission.
Not really something the average Joe does.

A quick check style mechanical oil pressure gauge is the same thing, I bought mine off Amazon.

Make sure it comes with 1/8npt adapters.

Daily driver/ workhorse: 1994 2500SLT 4x4 Auto. Hewitt EGT, Boost, Trans gauges, Under hood Mech FP gauge, Trident fuel lines, Tork Tek OFV, Mag-Hytec DD Transmission Pan, Ford manual hub conversion, Diamond eye 4" turbo back, 37337 Upgrade. 260K

98 2500slt 4x4 ECLB moldy G56, south bend clutch 3rd gen trac bar , boxed control arms, billet tappet cover w/ dual breathers trident fuel lines, Tork Tek OFV, 4' stainless side dump with muffler 240k
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post #6 of 27 (permalink) Old 04-15-2019, 06:12 PM
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Something like this (I hate to suggest HF, but it's an example) or this. I think Lisle used to make a nice, relatively inexpensive set - but I can't find it on their site (maybe it was KD Tools, which is no more). Advance Auto Parts has one by A&E, and there's probably about a million others out there. Check the length of hose for the gauge to be sure it will reach up to where you can read the gauge.
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'96 2500 club-cab, long bed, 2WD - Dipricol trans/boost/pyro gauges, ISSPRO fuel pressure gauge, +2qt Chrysler trans pan, Sport headlight retrofit & suvlights conversion harness, fuel heater deleted, KDP tabbed, Raybestos WC37290 (1-1/16") wheel cylinders
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post #7 of 27 (permalink) Old 04-16-2019, 12:08 AM Thread Starter
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Awesome, thanks! I’ll pick a set in the morning.
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post #8 of 27 (permalink) Old 04-16-2019, 07:10 PM
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I have that exact OTC set, got mine on amazon though, that 2 day shipping gets me every time.

Anyway, here is the page from the service manual that I found helpful with the 4th gear section highlighted in red:

shows 68-72psi in 4th with foot off throttle, rising to 90-120, maybe even as high as 130psi full throttle.

Mine stayed around 5 and raised to about 10 when I was mashing on it. Obviously not enough to compress the killer spring and engage that OD brake clutch.
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Red Truck: 97 2500 4x4 ECLB 250k-ish, mostly stock.
Purple Truck: 01 1500 4x4 ECSB 12v Conversion, has all the 1996 3/4 ton stuff besides the body at this point.
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post #9 of 27 (permalink) Old 04-18-2019, 07:30 PM Thread Starter
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So while hunting for a pressure gauge, I gave my local transmission shop a call and asked if they had one and how much they’d charge. Guy said bring it down he’d hook it up to a scanner and check the pressures via OBD port no charge. They were busy so it sat a couple days. I went and picked it up a few minutes ago. The guy I picked it up from wasn’t the one who ran the tests and had minimal answers to the questions I had. He said it was then”switches”. Implying they were the “pressure switches”. I pulled up a picture of a pressure solenoid and transducer and he said yup them. He said the pressures were “there then all over the place”.

I don’t wanna second guess a professional, I’m sure he really is much more transmission inclined than I. I just wanted to make sure before spilling 40 more dollars of atf on my shop floor and a $70 or so on solenoid/transducer.

My question is, would the pcm still “command” overdrive with a bad pressure solenoid? I believe my pcm is “commanding” because it drops volts when it should. Right? And I tested the transducer and then even bypassed it with a resistor.

Could a bad lip seal or piston seal give similar symptoms to a scanner as a bad pressure solenoid?

Thanks Jarod! That’s a helpful manual page. Before I drop the pan I will still hook up a gauge. Would a bad pressure solenoid cause pressure to read low at the 4th gear port?
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post #10 of 27 (permalink) Old 04-18-2019, 09:43 PM
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I'm far from an expert, but I would question their knowledge, as I'm fairly certain the 47re has no way to check pressures via OBD2 to begin with. I certainly know I've not had access to a scanner that would show me much of anything on my trucks. Maybe 98s have more electronics, but you have a 97, and I have a 97 and a 96 so I'd think we've basically got the same stuff.

The transducer and solenoid are notorious for doing weird stuff but if your 1,2,3 and lockup is fine (with od off button lit up) and you have no slippage in those, I'd look elsewhere.

Take a look at the little chart on that page I posted, you can check at the governor pressure port to see if the transducer and sensor are regulating properly.

Here's the page showing the port locations:
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Red Truck: 97 2500 4x4 ECLB 250k-ish, mostly stock.
Purple Truck: 01 1500 4x4 ECSB 12v Conversion, has all the 1996 3/4 ton stuff besides the body at this point.
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post #11 of 27 (permalink) Old 04-19-2019, 12:28 AM Thread Starter
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Yeah, I got the vibe they weren’t as sure of what they were reading of the scanner as they lead on.

I definitely will and thanks for the manual pages! I picked up a pressure gauge this evening and will test it in the morning if the rain lets up a little.

I hope they’re right though! Seems easier and cheaper to through in a governor solenoid than a lip seal or piston seal.
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post #12 of 27 (permalink) Old 04-19-2019, 12:22 PM
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Yeah, I'd rather do a Gov solenoid and sensor any day, but with my purple truck project I've ruled out most everything but that lip seal.

On the plus side, since I've got 1-2-3 and lockup all healthy with no slippage just no OD at all I don't have to drop the entire transmission, just the OD housing, which is still far more of a chore than dropping the valve body but at least I don't have to unbolt the converter and all that mess.

There is service manuals available on here for free!

I figure posting the specific pages saves you some time trying to hunt through it all since I've already been through all this recently its fresh in my mind.

Certainly handy to have stashed somewhere just in case you need it though:
https://www.cumminsforum.com/forum/9...-download.html

The 96 one is most applicable for our trucks.

Keep us posted what you find out, I was always terrified of automatic transmissions, but I'm starting to see how simple they really are once you get past thinking its all wizards and fairy dust inside the thing.

Red Truck: 97 2500 4x4 ECLB 250k-ish, mostly stock.
Purple Truck: 01 1500 4x4 ECSB 12v Conversion, has all the 1996 3/4 ton stuff besides the body at this point.
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