[Slomo]

Hi all...I had posted earlier this year about possible converter drainback problems I had with about 3K miles on the clock (surging through the brakes in reverse after startup). Anyways, the possible converter drainback problem has been intermittent, and in the last couple weeks I have been having some new issues. My truck has grinded into 1st gear when coming to a stop (intermittent problem), and also skips from 1-3rd gear from a stop (also intermittent). Today my truck threw a P0869 code (using the on-off key procedure). I believe this is a "governor pressure sensor volts too low"? Took the truck to Autozone and code read "incorrect 2nd gear ratio". Just trying to add all this up before going taking the truck to the dealer...it has already been there once with no fix on the possible drainback issue. Any experience with this would be a help...missing my NV5600 already

 

[TransEngineer]

P0869 = Line Pressure High
P0732 = Gear Ratio Error in 2nd

Sounds like you have two different issues going on. The Line Pressure High code usually results from a bad LP sensor (giving too high a reading). If your line pressure is actually too high, that would likely be due to a problem with the line pressure control circuit (wiring or solenoid) or a stuck main regulator valve. Usually, if the reg valve is stuck, you get LOW pressure, not high, so I would discount the stuck valve.

Your dealer can read your line pressure (from the sensor) using a scan tool. He can also use a special adapter tool to tee in a mechanical pressure gauge (while your LP sensor is still hooked up), allowing him to confirm whether the sensor reading is accurate. So I would confirm the sensor is OK, and if so, then check the wiring (for the LP control circuit), and if OK then probably replace the solenoid assy (inside the trans).

Your other issue is the gear ratio error. If your PCM detects trans slippage, it will go into a mode called "logical limp-in", where it will shift from 1st gear directly to 4th. It will then remain in 4th until you come to a stop (or very slow speed), at which point it will go back to 1st. It will continue to shift between 1st and 4th (only) until you restart it. If Autozone found a P0732 code, then you likely have a cut or torn 2C clutch piston seal. The seal lips are bonded to the 2C clutch piston, so you probably need a new piston (52119655AA, $44.45 list from Mopar). Unfortunately, you have to pull the trans and tear it halfway down to get to this piston. Fortunately, you should still be under warranty!

If you drop the oil pan and valve body assy, you can air check the 2C clutch. The 2C, 4C, and LR clutches are all applied directly from the valve body, so if you pull the VB you can blow shop air into the clutch apply ports (about 30 psi) and see whether you get a big leak or not. These clutches all have a small bleed orifice, so you will get a little bit of air leakage, but nothing blatant. So if you need to replace the solenoid (for the high LP issue), you could air check the 2C clutch while you're in there.

 

[Slomo]

Great info...do you think it would still be useful to pull an oil sample before going to the dealer? I just want to cover all the bases here...the truck only has 6K miles on the clock, no boxes, etc.

 

[TransEngineer]

I don't think there's much point in pulling an oil sample. If I thought you had contamination in the oil (that led to these issues), then it would be useful, but in this case I don't see contaminated oil as being a likely contributor.

 

[Slomo]

Trans. technician is out at the dealership until 3-26...will keep an update on this one

 

[EVRE]

Update?
:subscribe:

 

[Slomo]

Truck just went into dealer Monday night. Unfortunately I got hit by a drunk driver 2 weeks ago also...so the truck is now at the dealer for bumper / intercooler repair, as well as the tranny problem

 

[Slomo]

Well just got the truck back from the dealer tonight. It was 15 minutes before closing and no one (of any knowledge) was around the Service Dept. to discuss the situation. Anyways what I do know from the service report... "Pump pressure low, R&R Transmission, replaced TC and Pump. Also cleaned Valve Body and Replaced filter" So I would like to call and talk to the Service Manager to find out a little more about why the Pump and TC were replaced. Hopefully I will get some answers. On a good note, the truck is shifting much better than before, firmer shifts with no 1-4 skipping

 

[EVRE]

I requested a copy of the mechanics notes. Sounds very suspiciously like what happen with my truck.

VERIFIED LINE PRESSURE AT 85 PSI / SHOULD BE PSI 125 DESIRED -- PAN REMOVED AND HAD ALUMINUM IN TRANS - REMOVED AND DISASSEMBLED FOUND TORQUE CONVERTER STATOR FAILED - DAMAGED PUMP AND PRESSURE REGULATOR WHICH WOULD STICK -- SERVICED VALVE BODY FLUSHED COOLER AND LINES - REINSTALLED W/ NEW TORQUE CONVERTER AND PUMP KIT - NEW FILTERS / PARTS AS LISTED - NEW FLUID - TESTDRIVEN - ROADTESTED GOOD
1 RL109671AF CONVERTER-TORQUE
1 RL029305AC PUMP KIT - TRANSMISSION
1 5179267AC FILTERPKG - TRANSMISSION OIL
1 5013470AD 4X4 FILTE - TRANSMISSION OIL
1 5010884AA *SEALER
14 68055894AA *FLUID-ATF+4

 

[Slomo]

Yeah sure does look similar...the only thing that was missing from my parts list was the 5179267AC FILTERPKG. I am not sure why they wouldn't have put new filters in. I may do the oil analysis in a little while to see how it looks. Anyways, I am disgusted to say the least that a 7-month old truck with 6K miles has these kinds of problems. I am really considering going to a G56 now

 

[TransEngineer]

Hmmmmm..........

Dealer says "pump pressure low", but you had a P0869 (Line Pressure High) fault code?

You might call back and talk to the tech. How did he know the pressure was low? Did he find a low reading from the LP sensor? Or find a P0868 (Line Pressure Low) fault code? Or did he check it with a hard gauge and find it was low?

I would wonder whether your LP sensor is giving a bad (too high) reading. That will cause the PCM to crank line pressure DOWN (giving you low pressure on a hard gauge). Did he happen to hook up a hard gauge, and compare the gauge reading to the sensor reading? That would confirm whether the sensor is reading accurately or not. Another possibility is the sensor wiring not being fully connected and latched. If that was the case, then obviously since they've pulled the trans out, the wiring has been unplugged and reconnected, so hopefully now it would be OK.

Might be worth it (for peace of mind) to have them double-check the LP sensor (against a hard gauge). Dealers have a special tool that lets them tee in a mechanical pressure gauge, so they can compare the sensor reading versus the gauge.

If you have a bad LP sensor, you are going to have continued problems.

 

[Slomo]

The dealer said there were a few codes stored in the computer...he did not name what they were, but that is where the they got the "low line pressure" code.

There was metal in the pan, and they were not sure what caused the low line pressure. I am guessing it was similar to something that happened in EVRE's case. I am just concerned now with whatever junk was in the bottom of the pan...how do I know that there is not any damage from the metal floating around in the transmission, or anything left that will cause damage in the future?

It is really tough to get good answers from dealers / service managers around here. Unfortunately we are in a pretty rural area, and the service really suffers around here. Asking questions pretty much gets you an "I don't care" attitude...sad, but that's the way it has been at more than one dealer around here

 

[EVRE]

The dealer said there were a few codes stored in the computer...he did not name what they were, but that is where the they got the "low line pressure" code.

There was metal in the pan, and they were not sure what caused the low line pressure. I am guessing it was similar to something that happened in EVRE's case. I am just concerned now with whatever junk was in the bottom of the pan...how do I know that there is not any damage from the metal floating around in the transmission, or anything left that will cause damage in the future?

It is really tough to get good answers from dealers / service managers around here. Unfortunately we are in a pretty rural area, and the service really suffers around here. Asking questions pretty much gets you an "I don't care" attitude...sad, but that's the way it has been at more than one dealer around here

This too has been my greatest concern. If the metal in the pan was able to bork the pump and make the pressure regulator sticky.. that means it was getting by the filter some how? If that is true, then I'm very concerned for the bearings and other wearing surfaces. Also, the clutches, they work now but how well did they fair with too low of pressure being applied to them? I had done more then a few good romps on her while passing or getting out on the highway.

TransEngineer, what do you think?

 

[TransEngineer]

It depends on what kind of metal debris you have, how much, and where it's located.

We often see complaints about "the pan full of metal" when in reality there is only a dusting of small flakes (like glitter) in the pan. This is fairly common and does not usually cause a problem. The metal parts in the trans will have some fine burrs, etc. on their edges, and although we try to clean them before assembly, you will typically get some "glitter" in the pan. The filters have a 60-micron rating so these small flakes should not get through the filter.

Sometimes you'll find large chunks of metal in the pan, due to a part failure. Often, this is a spun thrust washer that gets mangled up and dropped into the pan. Or, it could be a broken gear tooth. Obviously, these represent a problem that needs to be fixed, but if the resulting debris is a few large pieces, they can be removed and the rest of the trans is not usually damaged.

There are two instances where debris can cause other damage. First, an internal converter failure will send debris into the pump (the converter oil feed goes through the pump) and into the oil cooler. This can cause wear in the pump (resulting in low line pressure) and can clog or restrict the cooler, which can then cause repeat failure of the repaired trans, due to lack of cooler flow. Techs will usually check cooler flow (after a trans failure) to confirm whether the cooler is plugged or not. Some debris that gets blown into the cooler can also then get flushed out into the new trans, but RFE transmissions use a spin-on cooler return filter to trap any debris coming from the cooler. This helps to prevent further damage if the converter fails.

The other big debris issue is fine debris that gets generated and then spread throughout the trans. A typical cause would be a thrust bearing failure, where the failed bearing gets ground up into very tiny pieces. If you have a trans failure that generates a significant quantity of fine metal debris, then replacing the entire trans may be a good idea. That fine debris may be contaminating the planetary gearsets, and you can't easily clean or flush out the needle bearings inside the pinion gears. So that would be a concern for me.