Started working on this problem using troubleshooting table supplied by Johnny Cetane. Very useful but still stuck.

Here is the problem. Each time I start the truck (can be hot or cold), the very first time I shift from 1st to 2nd, the tranny “sticks” from approx 1500 to 1800 then shifts and a trouble code comes up (P0720). It only happens on the 1st shift then continues performing just the way it should. No other problems, speedo and tach function smoothly and the rest of the day truck runs until I shut it off and restart.

I have already replaced the wheel speed sensor and checked the connections for any defects.

I What is killing me is the problem being so intermittent. need some insight on this problem.

 

change the tranny fluid and filter and see what happens

 

About 7 months ago I completely flushed tranny and changed fluid. Checked fluid and did not smeel burnt. If it was the fluid wouldn't do this all the time?

 

never know fer sure.............I would change it and the filter

 

if a tranny slips, sticks, screws up or does anything funny, change the fluid, first and best thing you should always do, oh and did you change the filter again after you flushed the tranny???? biggest problem with flushing the tranny is the particles the flush breaks loose and leaves behind for the filter to catch later.......

 

Gov. Solenoid
Governor Gasket

Shift Solenoids

All Possibilities and if the Gov. solenoid and Gasket haven't been changed i would start there 20 to 30 min. job with a lift!

 

Yes filter was changed. The problem only happens once after startup. Regarding the Solenoid, gotta read up on that.
Thanks for the ideas. I have something to do this weekend, yepee

 

startup when its cold or everytime you start it, because if it was just when it was cold the fluid would be thicker and have a harder time passing through the clogged filter, then when its warm and the fluids thinner then it will pass right through the filter even though its dirty, just a thought at quarter till 2 in the morning

 

The problem happens after startup (hot or cold). Just the first time it shifts from 1st to 2nd but after that it runs great.

 

Clean your IAT

Its not going to hurt anything

cleaning the IAT sensor on the 1998-2002 24V diesel engine. The IAT sensor measures the temperature of the intake nmanifold. The ECM uses this sensor reading to set injection timing and adjust the air-fuel ratio. If the fuel mileage and power output of you engine seem low, some owners have found improvement in EGT, fuel economy, and power after cleaning carbon from the IAT sensor in at the rear of the intage manifold. Engine with exhaust brakes are particularly prone to IAT sensor fouling because soot is blown back into the intake during valve overlap. Smokingdiesel.com has an information page about problems caused by the IAT sensor.

The only tool you need is a 3/8" ratchet with a 6" extension and 13/16" socket.

The IAT sensor is found on the driver's side of the engine, almost at the back of the intake manifold.


Unplug the electrical connector from the sensor. You will need to spread the connect tab away from the sensor body to unplug the sensor. After the connector has been removed, use a 13/16" deep well socket, 6" extension, and ratchet to unscrew the sensor from the manifold.


The sensor on the left had 20,000 miles on it, and it was covered with soot. After a shot of carburator cleaner, you can see the sensor element inside the cage. Screw the clean IAT sensor back into the manifold, torque it to 10 ft-lb, and reattach the connector.




After seeing how much carbon was on after 20k I figured mine was going to be 5 times as worse being that my truck has over 130k on it. Too my surprise it really wasn't bad at all. I'm sure it depends on what mods you have done & how you drive your truck. I got my truck used with 120k but don't think the previous owner did too much maintenance to the truck, but I could be wrong. It doesn't take long at all to clean the hardest part is getting it off the truck.
*Note - If you are double jointed the job will go a lot faster....
Temperature
Resistance
30°
40K
32°
30k to 36k ohms
76°
13K ohms
77°
9k to 11k ohms
81°
6.87K ohms
122°
3k to 4k ohms
130°
4K ohms
167°
600 to 675 ohms
212°
600 to 675 ohms
Replacement Sensor: