No OD at WFO

[hdm48]

OK guys, here's a wierd one. After washing my engine my transmission will not go into OD at wide f####ing open. I have gone to a friends transmission shop and pluged it in to a computer, no faults found. I have called every one that I can think of that might know what the problem is, even called Bill at DTT. I have replaced the TPS. I have cleaned ALL of the connections and disabled the trans temp switch.

Something has to tell the transmission how fast it's going and shift. It works OK in town, it delays a little getting on the freeway and down shifts a little early going up steep hills. All this makes me think that whatever it is that tells the transmission how fast the truck is going isn't doing it's job.

WHAT IS IT?

We don't have all the electronics that the newer trucks have, so it must be something simple, right?

I will entertain any and all ideas.



thanks



-Dave-

 

[BushWakr - RIP]

Hey Dave,



It was great to finally meet you as well. I hope you're going to make it for our Bomb day at PDR... we can swap some more info/stories too...



Now, did this malfunction start immediately after the engine wash down?

Was it showing ANY symptoms prior to this failure?

A little more detail might help us here... like what speeds are you seeing drop-out or sensitivity, etc.

I'm going to type in all the stuff that the "book" says may cause "No 3-4 Upshift condition".



bob.



1) 4th Gear overdrive switch (on dash) in OFF position.

2) Overdrive circuit fuse blown.

3) 4th Gear overdrive switch shorted, open, wires loose.

4) Overdrive solenoid or circuit wire loose, shorted open.

5) Solenoid feed orifice in valve body is blocked.

6) 4th Gear overdrive solenoid failure.

7) Sensor failure (vehicle speed sensor or coolant sensor)

8) Park/neutral switch is open or shorted, or switch wire to powertrain control module is damaged (loss of park/neutral input)

9) Powertrain control module faulty

10) TPS fault.

11) Transmission temp sensor fault (if equipped)

12) Overdrive piston seal failure.

13) Wrong overdrive piston spacer.

14) Low hydraulic pressure

15) Set-reset module faulty.



Those are the listed causes of no 3-4 failure condition.

Let me know if I can do any more looking, or if you need the "suggested repair" for one of these items, from "the book".

 

[B.G. Smith]

OD

Check trhe kick down cable going to the transmission, sounds like it might be stuck. bg

 

[hdm48]

Ok, here is some more detail. It started right after I washed the engine. As in during the dry off drive.

Since I did spray all of the engine and surounding area, I wonder if I have water hiding some where.

As far as sensitivity issue goes, it is very sensitive. Any more than 3/4 throttle and it will kick down. Even if I'm doing 70mph!

The TPS is brand new from Cummins and is adjusted.

Bob, if you have a factory manual that shows how to check all of the items you listed, I would be very interested in looking at it.

I'm sure it's some thing simple. It's just sitting there looking at me running around and laughing at me. And I know what it's thinking, "and you call yourself a mechanic?" he-he-he-catch me if you can!



ARGH!!!





--Dave--