Engine/Transmission (1994 - 1998) No OD or TC Lockup and speed o dosen't work

[KEdenfield]

... on a 94 2wd I bought recently. I had the transmission rebuilt due to burned clutches and the VSS (sensor/connector portion not the gear portion) was replaced in the tail shaft. transmission shifts good now but no overdrive and no TC lockup. I pulled the plastic pickup gear out of the tail shaft housing and it had backed out a little and was hard to turn. I chucked the gear in my DeWalt and still got no speedo readout so I separated the sensor from the plastic gear housing and chucked up directly to the sensor tip... and got 30mph on the speedo with my drill turning max speed (1500rpm) which seemed like a slow readout for turning that fast. I pushed the gear in and felt a detent and it became much easier to turn so I thought I had my problem solved.



Now I get a speedo readout, but it is always low. Only gets to about 35mph on the interstate while I'm actually going about 60-65mph (in 3rd gear because it won't shift to OD).



I checked the orange, white/orange, and black/blue wires at the computer connection and they seemed tight so I disconnected the connector and cleaned the pins and sockets with electrical contact cleaner because of some residue on the pins.



Still no OD and speedo still reads low.



Any ideas? Trying to go anywhere on the interstate with no OD sucks down that $4/gal fuel real fast!

 

[KEdenfield]

Thanks for all the help...

 

[dieselshadow]

First off with a response like that you are more than likely to prevent people from helping you. Give people some time.



Your transmission's over drive and torque converter lock up functions are controlled by the truck's computer. Assuming that everything is okay with the rest of your trucks electrical system, I would look at the 2 connectors on the driver's side of the transmission. They are just above the pan rail. One of those connectors carries the power and two ground leads for the lock up and OD solenoids. If the connection is good, your next step in troubleshooting would be to find out if the solenoids are okay. These are normally replaced or at least checked out during a transmission overhaul. You can check them by a volt meter across the pins and check for continuity. I suspect that since both functions are not working your problem lives in either the connection or with the truck's PCM.

 

[TBurow]

check for power and ground on the outer pins of the connector, the center one is signal to the pcm the black with white stripe is ground and the other is 8v refrence from the pcm the crank sensor also uses the same power. so if you have no power or less then 7. 5v at the power wire(orange i think) check the power at the crank sensor if its good there you have a bad wire. usually on top of the trans where it meets the engine. if power is good check the ground side. trr grounding the wire and spin the sensor if no different i would suspect the sensor has been damaged. rock auto has them for $23. i just bought one for my dads truck. hope this helps.

 

[KLockliear]

TCC lockup is controlled by the computer, but on a 94 truck (47RH trans) the 3-4 shift is hydraulic not electric.



Sorry I don't have your answer, but I know that much. Call a good trans shop and ask them. DTT's number (off the top of my head) is 866-504-4002.



Also, as mentioned, your second post was unwarranted. This is a free site for people - no one is sitting here like on a tech line to help you out. People WILL help when they get to reading it. If I were you, I'd delete that 2nd post.

 

[dieselshadow]

The 94 and 95 automatics were both were equiped with the 47rh. The 47rh has two solenoids controlled by the PCM for TC lock up and the 3-4 shift. Both functions are hydraulic in nature but controlled by these two solenoids. By grounding the circuit the solenoid activates and engages its function. If the PCM does not see the pulses from the crank position sensor when the engine is running, the alternator will not work. You also lose the transmission overdrive and lockup functions. The PCM has very limited functions on these particular years.

 

[biggy238]

If I remember correctly, on my 96 (RE) the PCM relies on the Turbine speed sensor for shifting. If it fails, it then uses the speedometer. You could have a problem with both sensors.



Also, have you checked the numbers around the outside of the speedo? The corresponding number range on the speedo for the number of teeth on the gear needs to be placed accordingly. I think it has to be to the top to read correctly.

 

[NKenny]

Without dropping the transmission pan, would person be able to tell whether the OD solenoid is functioning? Is that the continuity reading mentioned above? My truck will shift into lock-up, but still not OD. I have checked and cleaned the connection, have a resistor in the temp line, and have a Potentionemter instead of the TSS.