No shift, trans tore down 3 times, electrics changed TPS issue

[Wild and Free]

The AC noise affects the 24v autos with the converter lock/unlock issues at low speeds and sometimes indecisive shift points.

[dseabaugh]

This may be helpful to someone sometime.

Info came from a guy on TDR.

cerberusiam

 

Join Date Oct 2001 Location McDonough GA Posts 7,231

Yikes, should have come here the first time you had problems. Would have saved a lot of $$ and hassle.

OD and lockup are all computer controlled. The TPS contributes to when it shifts but it is far form all. The PCM ultimately determines if lockup and OD happen. The first thing you need to do is verify it is mechanical or electronic issue.

Validate you have 12 volts on one wire in the trans control harness with the key on. There will be one wire that is larger than the others and will be hot all the time with key on. If you cannot find 12 volts you have a problem in the harness somewhere. This is the power for the solenoids for TCC and OD so it must work or all rebuilding will be to no avail.

If you have power to the trans, go to Radio shack and get yourslef 2 switches, single pole single throw simple on and off switches. Get 2 1/2 watt 33 ohm resistors, they usually have them in bulk. A roll of 18 gauge wire. Probbaly a total of $7-10. You wan tto wire these switches into the round trans control plug on the transmission.

IIRC, pine #6 is the OD, pin #7 is the lockup. These are the sense wires the PCM grounds to activate the functions. Tap each wire with a scotch loc and run each wire to a seprate switch. From the other side of the switch wire to the resistor then to a chassis ground. Whne you flip the switch to on you will complete the circuit and activate the solenoids for TCC and OD. If you transmission is good and all the hard parts work they will engage. That tells you if it is mechanical or electronic and if it works you now have your functionality back, albeit manually but it is better than nothing.

All your pressure slook good except reverse. It should go to 300 psi, or thereabouts, and stay. Dropping like that sounds like there is a leak somewhere. Two components engage for reverse, rear servo and direct clutch pack. Either could have a leak that is dropping the pressure. That wil cause some shudder in drive and maybe reverse if that pressure is low, under heavy load it will slip. Neither problem will cause OD or TCC to not engage.

Gov pressure is related to wheel speed so until you get the wheels rolling that pressure will geberally be zero. If you put the truck on jack stands the gov pressure should rouhgly follow wheen speed up to about 60 mph or so.

OD port will show no pressure until the solenoid engages. Wire in the mystery switch and see if it will enagage then test the pressure for accuracy.

Hope this helps get you on the right track.

[Ilikeoldfords]

Now that I re read everything, it seems that you are having some serious pressure issues inside the tranny. We should probably determine if it is an internal transmission problem (valvebody, pump, solenoid, etc.) or if the trans is getting wrong electrical signals sent to it to do these things. It sounds like everything is working on the electrical side apart from a possible PCM. The PCM could be causing incorrect voltage signals or no signals at all. Would a faulty PCM be causing the pressure issues inside the tranny? I am not sure. Honestly, I would be having that PCM tested. That at least would rule it out as a possibility. If it is good, we have some bigger issues to look at.

[dseabaugh]

Tested wires for a few more days and tested pressures. They sucked on O.D. and Reverse. cerberusium on TDR told my how to make it shift with mistery switches.  Took it for a 23 mile trip and it finally shifted halfway normal at 7 miles on the highway. here's the final answer. Had to be air locked or pistons still too tight in the bore with the teflon seals and steel  piston rings. something else that tells me it was air locked is I had to put in 1 more qt of oil when I got home.  Checked all the pressures today. All are 20# over specs except reverse which runs a steady 250 any speed or rpm and O.D. that runs a steady 100 psi.  Tried to  run off computer again. No go. Checked pressures on trans again. They be good.  all are 20# over specs except O.D. which is 100# and reverse that runs a steady 250# nomatter what the speed.  plugged in computer, still won't shift except 1-2-3
Works fine on mistery switches.
will replace that p.o.crapola. in dec. when I figure we have enough $ saved to buy one. Thanks for everyone's help. it is VERY VERY much appreciated.

thanks

d