Hi all

I have been fixing various problems with this 3500. the newest issue is sometimes (not everytime) after starting the truck, and taking off the truck (auto) wont go out of 1st gear it wont shift kinda max's out at 2k rpms, when in neutral it revs fine, so I have found that if I unhook the batteries (both) and rehook them the problems goes away,

now when I say goes away, everytime I start the truck it locks up in first but sometimes it will take off if I depress the accel pedal, several times, it takes off and then drives normal, sometimes it just doesn't shift out of first, like mentioned above,

now I replaced the APPS with a known good one frome a stick shift, I had to wire tie the cable that goes to the tranny to the APPS frame as there is no hole for it on a stick shift one

I changed the APPS for other symptoms I had a few months ago, now things have progressed to this

I have checked the key on off feature and no codes showed up , also the truck seems to lack power compared to my 2500 I had a few monthes ago,

 

I have replaced the output speed sensor in the tranny, the rear dif. speed sensor, the transfer pump (lift pump) the apps

also my truck wont boost past 20 PSI never, I am thinking PCM

 

Not up shifting is usually the gov. transducer and /or solenoid, on the valvebody.
For the power issue, did you check the fuel pressure?

 

would the trans things you mentioned reset after the batteries were unhooked and rehooked. also the fp is about 18-20 at idle wot is about 10-11

 

Boost 18-20 is normal for a stock truck, That cable you tied off to the frame is the tranny kickdown, if thats not adjusted properly then it wont shift properly, you can switch apps from bracket to bracket, and adjust the voltage with a mulitmeter to get it back into spec, there are how to threads on this site, its a pretty simple procedure, I'm with J-fox on the tranny sensors, a good scantool will monitor tranny pressure and confirm if the sensors are bad, I did an older truck about a yr ago replaced the sensors and noticed that one of them has a filter screen on it and it was plugged solid with tranny dirt (same stuff you find on the magnet) If it had been my truck I would have tried to clean it off first to confirm that this would cause the tranny to stay in gear. after swapping both sensors the truck shifted properly

 

thanks for the responses the frame i referred to was the frame of the apps unit, I tried to djust it like the one that was on there, I already through away the old one, I will check the inside sensors, and such, soon