leeboy

I first noticed this happening a few months ago. Driving steadily around 70km's i would notice the tranny would want to down shift very briefly for a second then it would go back to normal. If i held the pedal realy steady, it would do it 3-4 times in a row.....Until i gave it a little more gas to speed up then it would stay in overdirve....This past weekend, i was on a highway run, and i noticed it was doing it at 80 kms.....then 100 kms...But if i put the foot in the pedal, it doesnt do it. So, today i was climbing a hill on the highway, and around 80 kms, it was in overdrive, and it started to surge, its like it kicks down....the rpms go up...then back....all in a couple seconds at the most. But repeats itself until i speed up or so.......The tranny fluid was changed about 1 1/2 years ago....Other than that, it changes perfect, theres no slipping or anything.....Any ideas on teh surge?

Dinner

Could be a bad ground/electrical problem throughout the tranny circuit causing it to want to lock and unlock. I would make sure all connections at batteries, alternator and grounds are in good condition. Next thing you could do if you want is wrap the ground wire coming from off of the alternator in tin foil.

dozer12216

Some other issues that have been mentioned from time to time:
Overfill tranny by one pint to make sure not pulling air instead of ATF...
Make sure brake switch not bouncing on/off.
Make sure connection at sensor on estension is good.
Check all electrical connections for batteries and alternator.
Inspect brushes in alternator to make sure not greasy or worn out.
Wrap alum foil around wiring from alt to battery to shield RFI. Corroded wiring will make worse.
Install old ignition condenser to alt output terminal and a ground to case. Takes care of weak condenser in alt or noise (RFI) from alt.
Make sure both batteries are in good condition.

leeboy

After reading your answers today...A few months ago, i noticed that it takes a few minutes for my altenator gauge to come up......sometimes after a minute or 2, my check gauge light comes on ( ding..ding...ding.. noise) telling me my altenator gauge hasnt come up yet. I did a altenator test after that started happening, and altenaotr was good, but one of my batteries was weaker than the other...(my mechanic said i should change it this winter) My altenator gauge after driving is more on the charging side than the even side....I thought the tranny problem would be mechanical, not electrical...

Dinner

The electrical on these trucks can do wonders to the trannies, after all...they are 47re's not 47rh's.

Is this battery that is "weak" considered a bad battery by Load Test? Or is it considered weak because it has a lower voltage than the other?

leeboy

The battery is 2-3 volts less than the other one....I looked at my battery connections and they are a little green/white -dried crust around them...It seems to be surging a little more now than in the early fall....

kit

my 1991 D250 is doing the same thing, and I only have one battery and it is just started overcharging at times and other times it charges normally. Today it started over charging so I had a friend sit in the drivers seat with the motor running and I shook some wires around till the needle in the volt gauge jumped and as soon as I tapped on this little metal electrical box with a 2 wire harness mounted upper center on the fire wall it started to jump, so I unplugged it so I would make it home with out frying my battery. I dont rely no what this box is but I noticed that the volt gauge was slowly dropping so I assume I was no longer charging my battery.

BIGSHOOTER23

i had a slight shudder or surging to my tranny also. did it around 45-55 really bad and stick it in 4x4 got alot worse. after going back and forth with the dealer for a new tranny they called some specialist and it was as simple as changing out a wire to a new ground.

leeboy

What wire did you change?

gellibee

I am having the same issue, more info concerning what wire would be great!
Thanks

slayerfish

My '99 had the torque convertor keep locking/unlocking. Sounds like the same issue. Had the pcm reflashed at the dealer and it fixed it.

rams2500

My 99 has done the same thing and have the problem fixed for now. It started unlocking again a couple days ago. Cleaned the grounds and checked connections and so far so good. Can a '97 Cummins have the same problem or just the 2nd gen trucks? Thanks and good luck

leeboy

Besides the battery terminals....Which grounds (if you could name them all) should i clean, going to do it in a warm shop monday)

jrs_dodge_diesel

I recently had this same issue where the lockup clutch would go engage/disengage repeatedly in 3rd and 4th gear. I searched here for an answer and found that the first thing I should do is clean the ground wires. I did that and my transmission shifts like normal again.

There are 6 spots to clean. Each negative battery terminal (1,2). There is a wire that runs from each negative battery terminal to the body of the truck with an eye terminal (3,4). Not only did I clean the connector, I took some sandpaper and took the sheet metal to bare metal to give a better electrical connection. The most critical wire to clean is the one on the PCM (Powertrain Control Module) which sits on the firewall, on the passenger side (5,6). The PCM is what controls the lockup clutch. There is a ground wire on it that runs to the firewall. On my truck, I did not like the amount of corrosion I saw on my PCM ground wire, so I replaced it. Made a new one with soldered eye terminals to minimize corrosion. I also sanded the firewall and PCM too where the ends connect.

It am confident in saying that it completely cured the problem with my transmission.

gellibee

Thanks for the detailed information.