Thank you, sir.

I tried turning off the O/D switch and it didn't influence it at all. I believe that it is the driveshaft, or at least some component outside of the transmission, because a loud clang accompanies the lurch sometimes.

Another oddity, it was chilly here today, and O/D would not engage, even on the highway. It engaged perfectly yesterday. Do I have a faulty Solenoid, sir?

I checked the fluid this morning and it was still bright and clear.

There was a TSB on that many years ago. It also affected the single piece rear shafts. The slip spline at the rear shaft on the transfer case could bind and release. My experience the shorter the wheel base the worse the condition. It never hurt anything but was a common concern by many customers.

I think OD is defeated by the PCM until engine temperature gets up to a certain threshold. Additionally in certain applications there is an external temp sensor for the trans and in others it’s internal - part of the OD/LU solenoid assembly which has a thermistor built in. If it sees a low temp you won’t get OD, too hot and OD is defeated as well.

NitrousN, thank you very much! I have the shortest wheelbase 1500 for that year. This makes alot of sense, and is what I believe is happening to my truck.

Transman, this makes perfect sense, because overdrive engaged this afternoon after school. It operated smoothly and strongly for two hours, with no glitches. So the low temp thermistor must be exactly what was preventing my OD from engaging. Thank you so much for your help through all of this.

On the RH trans the trans temp sensors are often on the output/front line on the trans. Close to where it screws into the case. 2 wire connector

I believe diesel gets this external sensor.

I believe gas uses the internal sensor - part of the OD/LU solenoid assembly.

I've got a weird issue, now. So, when I was coming to a light earlier today my transmission felt like it didn't downshift all the way, and went I went to roll forward the engine just revved, without catching.

I pulled off onto the shoulder, and the transmission downshifted, and then I was able to jump back out into traffic normally. About ten minutes later I was pulling out of a neighborhood, and the same issue happened. I let back on the throttle, and eased forward and first gear engaged normally.

I tested it going to school, and when I started forward with light throttle pressure the transmission would engage normally.

There have been no hard shifts, the fluid is bright and does not smell burned in any way. What am I facing here?

I do not rev the motor hard, so my throttle input for all of this was light to medium, no more than 1500 rpms.

If it does it again and you are at a slow enough speed try doing a manual pull down of the shifter without getting off the throttle.

If it instantly starts to engage my first guess is it is stuck in high gear. May feel like neutral but most stock converters stall around 1700-2000 so if it’s in 3rd you aren’t against the converter. The true test for a gov issue is to install a 0-80 lb. gauge and see what’s happening when you get this issue. Pressure should track close to vehicle speed, 5 psi tab 5 mph, etc.

Is this an odd issue to have occur a few days after a new rebuild?

It had no issues shifting, up until this morning. If it turns out to be the governor, then what could I have messed up during the rebuild, sir?

If it shifted ok then developed this issue I don’t think you screwed anything up.

My first guess is debris.

There are valve body issues that can cause strange behaviors so that is why I always start by checking governor pressure as part of the process of elimination.

If the truck upshifts and downshifts manually then your clutches and bands are fine, likely It’s your control system that is causing issues. Governor and valve body.

Is there any chance of it working itself out, if it's debris? Or would I have to have the trans pulled again and manually clean the governor? I know that I can drop the valve body and clean it with it in place.

Not this weekend, unfortunately I am close to the impact path of Hurricane Delta.

Most of the time a sticky governor can fix itself. Lots of quick stop and go and shifting to reverse can help loosen a sticky governor. Seems like the more you work it by jarring the output shaft the better it can get. I would say in my experience 90 percent fix them selves.

Thank you, Nitrous!

I will take this to heart and do as much quick stop and go as I can.

The transmission started shifting really well, with the shift points almost exactly where my transmission used to be. Until the lack of engagement this morning I was thinking that it was breaking in really well. The transmission did this under identical conditions both times, this morning. Coming to a stop, transmission doesn't feel like it shifted fully into first, then trying to start rolling forward, engine revs up but truck doesn't want to catch. Give it more throttle, then engages.

When that happens try manual 1st gear and see what it does. As soon as you feel the slippage when trying to go shift it to first. If it then takes off like it normally should the governor had hung up.

Thank you again, sir. The first part of my drive is all rural highway. It wasn't until I got into the town where my trade school is at that I encountered this. So about 45 mins of highway driving and then the first light, it did this.

Update.

Truck started lurching when I pulled into my neighborhood coming home from school today.

Manged to limp rest of way home with truck jumping between what felt like 1st and 2nd gear.

Truck now dies after engine revs up and down 1000 rpms when shifting into Drive, 1, or Reverse.

Please help.


Fluid is still bright and clean. No burned smell.

Is this a bad torque converter? Could I have a band issue?

Now the engine won't start. The starter cranks the motor over strongly, and I can hear the fuel pump engaging strongly, too.

I had just filled up the tank, and it wasn't a mile and a half down the road that all of this happened. Is there an engine condition that can cause this, and this is just coincidental with the trans issues?

I appreciate everyone's help. I'm out of my depth here, and this truck has been great to me. The truck not starting has only ever happened when my battery was going out, or an ignition switch was bad. This is definitely not normal for this truck.

Can you check for codes? Its either something electronic that's failed or else you got a bad tank of fuel. If possible try to pump a sample through from the tanks pump into a clear container.

Thank you, Nitrous. Unfortunately I didn't have the time or the ability to pull a fuel sample. This makes perfect sense that it would be electrical, and is only coincidental that it is happening around the time of my trans rebuild. The truck is a 1994 1500 with the 5.9 and is OBD 1. I do not have a code reader, so was unable to check codes. I did check the connection to the ECM, and checked my fuses. I even swapped my fuel pump relay with a known good relay.

This morning it cranked normally, gave me no issues on the way to school, and drove really well. When passing by an overpass I thought I heard a loud whining, but figured this could just be the gearsets that I changed in the OD unit. Transman warned me there could be more noise. To be fair I was in OD pushing 2000 rpms, so my rate of speed was up.

When trying to leave the school this afternoon the truck was doing the exact same thing as yesterday. Lurching, not wanting to go over 5mph, running really rough, sounding like it almost wanted to backfire. I limped to a parking lot, and had the truck towed to the mechanic who did the trans swap. I suspect a fuel pump going bad, and only acting up in the heat, now. It was pretty hot yesterday afternoon and today. This morning was nice and cool so may have been able to operate normally.

I did put the truck in park and revved the engine. It revved up to 2500 rpms normally, with no stuttering. I don't know if this is a sign of anything, or the truck simply being able to make rpms because in a zero load situation.

For now you need to get it running correctly. Once running you can work out the bugs. A poor running or erratic running engine can cause a person to think there are other problems. Was the check engine light on? Knowing codes would be helpful. One other item that comes to mind is the crank sensor. I have seen these damaged with transmission removals.