Berryman's Chemtool

I was experiencing a slight slip in the transmission first thing in the morning when the temps were below 60 degrees in my 2002 Jeep Grand Cherokee (42RE). Per recommendations of many of the regulars on this forum to combat such an issue, I added a can of Berryman’s B-12 Chemtool to the fluid. I drove it a couple times and everything seemed fine. It sat for a week or so, went to drive it tonight, and now the check engine light has come on and the transmission is slipping badly. I don’t know if they have changed anything with that stuff or what, but I just wanted to give a heads up that this may not be such a hot idea anymore, for whatever reason. I will try changing the filter and top up with some fresh ATF+4 (and probably drain and refill a few times) and hope for the best. I don’t have a code reader right now, so I can’t pull the codes and don’t want to drive it to the auto parts store the way it is now, but am pretty sure they are related to the slip. If anyone has any further advice or wisdom, I am listening.

Don’t mess around! Get all that contaminated fluid out and get new ATF+4 fluid back in the tranny with a tranny fluid exchange machine along with a pan drop. And then cross your fingers.


This is one case where I agree with tester about the fluid exchange machine.

How many miles on the vehicle and how often has the fluid/filter been changed?

I went to pull the vehicle into the garage to begin work, and noticed the transmission was no longer slipping (in retrospect, it may have initially been in second, a la “limp mode” since the RPMs never went above 1600 or so, it just didn’t seem to want to accelerate as briskly as usual). I figured I might try to go to AutoZone to use their code reader (less than a five minute drive away). I got out of my driveway and quickly realized it would not shift out of first. I turned around after driving about 200 yards, put it in the garage, and have since removed the pan to allow the fluid to drain. All looks normal; the fluid still looks bright red and there is minimal “fuzz” on the magnet. The fluid does, however, smell of the Berryman’s. I do have a couple of questions, though:

  1. I have heard of some people “purging” additional fluid from TorqueFlite based transmissions by starting the engine in neutral with the pan off. Could this do any harm, and should I try this or not?

  2. I had a thought that the additive may have damaged or destroyed shift solenoids, particularly since all was well, then I suddenly got a check engine light and the transmission wouldn’t work properly. Is this likely, and would it reflect in any codes I may get once I get a code reader on this thing?

I just saw ok4450’s inquiry. The vehicle has 129k miles on it and last had its fluid changed at 95k, about three years ago.

Your best input would probably come from transman (who has reported using Berryman’s with success and with no harm).

All I can say in response to those two questions is 1) don’t run it with the pan off. The only thing you’ll probably accomplish is burning up the pump; 2) if Berryman’s accelerated some problem I really doubt it would have done anything bad to the solenoids. It is a cleaner and, if anything, would have cleaned the shift solenoids.

Bust your filter open & see how it looks. I have seen reports from people who have done TransTune treatments (a Seafoam product) - TransTune is a cleaner made for transmissions. The reports I’ve seen basically say it does a lot of cleaning and then dumps a lot of gunk into the fluid. Any report I’ve seen has always been to run the SeaFoam briefly and then make sure you change the filter.

If what you’re looking for is complete DIY fluid exchange, I have also seen report of people accomplishing this with success though I have never tried it myself. The method that seems to me most likely to work without damaging the pump is to pull the cooler lines - hook up clear tubing to each one - submerge the intake line in fresh trans fluid (lots of it) and the other in a waste container. Run until the output fluid is about clean.

I’ve also seen people say this is another way to burn up a pump.

The reason I suspect the problem is electronic in nature is because of the sudden appearance of the check engine light (although I still need to pull the codes to verify that they pertain to the transmission) and the sudden and complete failure of the transmission, with the absence of any evidence of mechanical damage. The check engine light has been on twice in the last 3 1/2 years, both for an EVAP leak, and both times I found that the gas cap could stand to be a little tighter, and both times the code cleared on its own. I suspect that the slip I would occasionally get in the morning was caused by a leakdown of fluid from the torque converter (or elsewhere), as it would take less than five seconds for it to go away and would not happen again unless the vehicle was parked overnight, and would not occur during high temperatures. I was hoping that the Berryman’s would help clear this up, but seems to have either dramatically accelerated the problem or created a new problem. The plan now is to get a code reader so I can see why the check engine light has come on, replace trans filter, install a drain plug in the pan to ease fluid changes, and find a shop with a flush machine to do a fluid exchange, provided I can get this thing to shift beyond first gear.

Try cycling the key on three times, PCM faults should display in the odometer display.

The “Check Engine” Light Blinks Codes After Doing The “Key Dance” On Some Chrysler Vehicles With Mechanical Odometers.
For Some Others With LED Digital Odometers, One Can Try Pushing Both “Trip” And “Reset” Buttons (If It’s Got Them), Turning On The Ignition, Releasing The Buttons And Then Reading The Digital LED Codes On The Odometer.


Believe me, the Chemtool is not the cause of your problem. You stating that it drove fine after adding tells me that the seals inside your transmission are worn out. The Chemtool will soften the seals to allow the clutches to apply. The Chemtool works as you have found out. Your trans is just too worn out for it. Its a band aid, thats all. You need to get the codes read before you do anything else. Post back with the code/s. Get the fluid exchange if you want but dont be too disappointed if the slipping returns. F.Y.I. These transmissions are well known for their internal leakage problems.


Its quite possible that you were just in limp mode and furthermore quite possible that the Berryman’s had nothing to do with it - that is all coincidental. If the PCM sees anything it doesn’t like that is at all related to transmission function it will drop it to limp mode. I’m curious to know what comes out of the code reader.

Got a P1762 to display on the odometer. Thoughts? I have to go to work, so be back on here this afternoon.

P1762 - Governor Pressure Sensor Offset Improper Voltage

I would add that I’m one of those who touts B-12 but I’ve also stated I’ve used it for decades and that B-12 is not a miracle cure for every problem to come down the pike.

As Transman says, it’s a band-aid. That band-aid may make a difference when it comes to stopping the bleeding on a minor cut but if it’s a gash and hemorrhaging blood it won’t do as well.

You need to replace the governor pressure sensor (Transducer) This is a very common problem in these transmissions.
This is why you are in limp mode and the transmission wont shift.


A five minute research session on the code this morning led me to believe the same thing, transman. I appreciate your help. One other thing, though: I cannot find a listing for this part on Rock Auto or any of the other major auto parts store’s websites. Does it go by a different name or is this a dealer only part?

Mark9207 you asked how to flush the trans yourself. Its a 2 man job the way I do it. What I do is I get 2 gals of the fluid needed and disconnect the return line. I put a clear line on it and put it a 5 gal bucket. I then have the helper start the car and let it idle as I pour the 2 gals of fluid in it will run clean before it all poured in. I have the helper shut off the car as soon as it runs clear. As long as you keep the fluid running thru it and not let it go dry it will be fine. Then drop the pan and change the filter. Top the fluid and you should be good to go. I have had good luck doing it this way.

It looks like the governor pressure sensor is commonly referred to as the oil pressure sensor in the aftermarket. The Jeep dealership has the part in stock for $40 less than AutoZone and a whopping 31 cents more than RockAuto, so I will be getting it at the Jeep dealer. I’m hoping to get it all back together tonight and see if this completely fixes it.

So, To Help Others, How Did You Finally Get The Odometer to Display Digital LED DTCs ? Was It Hold The Trip And Reset Buttons And Turn The Key ?