No 4th gear or lockup

[Got HO?]

I posted this in the 911 forum too but this will probably get more views here...



This is driving me nuts!

I have a code P0123 (throttle position sensor voltage too high) code, transmission won't upshift into 4th gear & TC lockup is inoperative. Have replaced the following items:

Governor pressure sensor (transducer) & solenoid.

1/2, 3/4 shift solenoid pack.

Throttle position sensor.

Checked and cleaned all plug connectors on transmission & ECM's.



This is a hard fault that will appear just with the key turned on after erasing the code. Don't have to start the truck.

Has anyone run across this problem? I have a feeling that it may be harness related or a possible PCM :{

__________________

 

[JBlakeman]

No fix as of yet!

I've had this problem occur less than a week ago on my '03 w/ the 48RE. It's currently at the dealer, they checked the codes. Came up TPS sensor. Mechanic currently has no fix but is currently investigating a cause. Only thing with mine is the TC still locked in 3rd way up at 55MPH which was around 2300RPM on my engine. Weather may have been a factor since it occurred on a snowy day up here in Wisconsin.



Let me know if your dealer finds out a solution. I'm without my truck for now until they fix it!



Jon

 

[Got HO?]

No dealer. .



I am my own warranty station. Truck has 75k miles on it & isn't stock. I also have a problem with other people working on my truck from past warranty repair experiences. I'm on my own here



If your dealer finds the problem, please post the fix.



Thanks.

 

[jvjump]

I am having the same trouble. I think mine may be a torn seal for the overdrive. Found a few little piece in the pan and nothing else. All soleniods have check out. pcm is sending signal to trans.

 

[cerberusiam]

Check the harness that runs from the trans connector up to the firewall at the back of the engine. There is bracket or mount at the top of the trans tunnel that will wear on the harness and bare a wire or 2 and cause all kinds of strange behaviour. What most of you are describing is exactly what I have heard from those that have had this problem.

 

[JBlakeman]

Thanks cerberusiam,



I will call the dealer tomorrow and have them check into this. I'll report back if they find anything.



Jon

 

[Got HO?]

After lots of time spent looking at wiring diagrams & checking connectors etc, it looks like I may have a bad ECM. I have continuity from the TPS to the ECM, and continuity from the output side of the ECM to the PCM so the harness is good. Next step is to check actual voltage reaching the PCM (should be about 0. 6V at idle, DRB live data is showing 5V at the PCM, IOW, full throttle all the time)



Any DC techs out there that can tell me if I'm on the right track?

 

[TCDiesel]

After lots of time spent looking at wiring diagrams & checking connectors etc, it looks like I may have a bad ECM. I have continuity from the TPS to the ECM, and continuity from the output side of the ECM to the PCM so the harness is good. Next step is to check actual voltage reaching the CM (should be about 0. 6V at idle, DRAB live data is showing 5V at the PCM, IOW, full throttle all the time)



Any DC techs out there that can tell me if I'm on the right track?

The ECM on 2003 Only function is engine and cruise,Check all relays (transmission control relay) and fuses (#5 ,40A),The Pcm ( Pcm) controls all transmission functions on 2003, I have One I can send you to try. The PCM is located on passenger side firewall.

 

[TCDiesel]

I hope this will Help,if not I will delete it.

 

[Got HO?]

TWest,



is the trans. control relay in the fuse/relay box? I haven't checked it but I am getting normal 1st, 2nd & 3rd gear upshifts. Would I get any shift functions at all if the relay was bad? Fuses are good, checked with an ohm meter. I would be very interested in trying a PCM rather than buying one for test purposes only. pm me with your phone number please.



Thank you.

 

[Got HO?]

Todd,



great talking to you.



Thanks for the help. I will call you later.

Alan.

 

[HullD]

There is a tsb for this problem.

not sure what number it is.

The problem is moisture in computor plug at right hand firewall on the 03.

A kit comes with new harness seals or they replace the pcm if the pins in it are coroded.

Had to have this done on my 03 for the same problem.

 

[Got HO?]

Yes,



I had the recall done a while ago FWIW. I believe however, that my PCM has failed.

 

[Got HO?]

The ECM on 2003 Only function is engine and cruise,Check all relays (transmission control relay) and fuses (#5 ,40A),The Pcm ( Pcm) controls all transmission functions on 2003, I have One I can send you to try. The PCM is located on passenger side firewall.

Todd,



I sent you an e-mail.



Alan

 

[gungrey]

I have a an 03 that had the same problem and the problem was as HullD was explaining.

 

[sag2]

If you loose the ground side of the TPS the voltage goes to 5v.

 

[Got HO?]

Thanks to TWest who sent me a "test unit" PCM, my truck is now shifting properly. Its great that there are fellow TDR members who are willing to help dummies like me Oo.



Now, anyone have a good used PCM for a 2003 2500 A/T slt for sale?

 

[HullD]

If the moisture problem contaminated the pcm the dealer was to replace it too.

check the condition of the pins in the pcm and check with a dealer for waranty.

 

[JBlakeman]

Truck back from dealer, shifting fine.

All,



Picked up my truck today. Dealer mechanic noticed nothing unusual with any connectors or PCM. He did secure all connectors and took for a test drive. To no one's surprise it didn't exhibit the non-OD issue as when I dropped it off So... . he stated that if it happens again and it's during the day (when the dealer is opened) to bring the truck in to them right away (keep it running and in gear) and they can run a DRBII scan to determine failure of PCM or another issue.



For my peace of mind, after I got home I checked all the wires and connections on the PCM and no corrison seems to be present. But I do have the tendency of pressure washing my engine due to all the road-salt in the winter so I may take care to avoid some areas in the future when cleaning under the hood.



So for now it's shifting normally once again. At least all costs were billed to DC as it was covered under the 7/70 warranty.



Jon