3.0 to 4.0 no 3/4 gear

[fatheadff]

I bought a 93 Ranger from a guy that swapped a 3.0 to a 4.0. He installed the wiring harness as well. After putting in two transmission that had no 4th gear he decided to get rid of the truck. I had a 93 with a good tranny in it. I changed them out and still the truck has no 4th gear or od. I have replaced the pcm, vacuum modulator,vss,cruise control servo. I used a break out box and all the voltages seem to match but it seems i am overlooking something easy. What controls the 3/4 shift that i havent tried yet. Cluster,abs mod,rear wheel speed sensor? i am out of ideas anyone heard of this or can point me in the right direction. Thank you

 

[Nhaz]

I have had the ecc-IV box short out on me and cause a lack of O/D. In any case its easy to pull it out and have a look. If you see lots of corrosion in the box I would say chances are you found it.

 

[fatheadff]

If you are refering to the ecm/pcm comp. in the firewall on the driver side i replaced it with a new one and there was no corrosion on there. But im not sure if thats what you are calling the ecc IV box

 

[-Nathan-]

i know this isnt really an answer to your question...but have you thought about a 5 speed swap?

 

[adsm08]

If you are refering to the ecm/pcm comp. in the firewall on the driver side i replaced it with a new one and there was no corrosion on there. But im not sure if thats what you are calling the ecc IV box

That would be the eec-IV box.

Something is causing it to not get the signal to shift up. I'd be looking at wires.

 

[fatheadff]

I checked voltages at the breakout box and they seem to be in specs and I ohm checked the wires from the 60 pin connector to the transmission connector and they are not grounded out. What tells the ECM to shift. Psom,tps,about to light a match.

 

[adsm08]

TPS and VSS usually.

But if those are no good you'd be stuck in 1st. I'd be looking at the trans side of the circuit.

 

[SMTGREG]

Are there any codes?
Is there good vacuum AT the modulator valve?
With this being a swap. Make sure the trans linkage is correct and the trans is in the OD position, one click past neutral, if in drive it locks out 4 th gear. Check for power at the red wire at the trans connector with the key on. On the 4.0 the 3/4 shift valve gets its ground with the orange / yellow wire, back to pin 52 in the EEC connector.( the 3.0 pin location was pin 51). The resistance between pins 52 and 57 should be 26 - 40 ohms.
Inputs for gear shift control from PCM are throttle position, vehicle speed missing or erroneous, RPM signal and vacuum to the modulator valve.Just another thought is the pin in the trans behind the modulator valve

 

[fatheadff]

It does have good vacuum. The pin is in the mod I made sure when I replaced it to see if that was the problem. With the break out box I had .38 volts on pin 52&53 at 55mph. I installed a new speed sensor. Does the programmable speed thing in the cluster have anything to do with it. I also read on a wiring diag that the speed sensor runs into the antilock brake control unit as well. What about the coolant temp sensor. The tps voltage was a little high but not way out of range. It runs and shifts great it just doesn't have 4th gear or tc lockup

 

[SMTGREG]

Voltage on pins 52 and 53 should be 12 volts with key on. Voltage on pin 52 should drop to less than 1 volt when trans commanded to shift. Pin 53 should drop to less than 1 volt when TCC commanded on. IF you have 12 volts uncommanded and less than 1 volt when commanded on the trans should be shifting you can just ground terminal 52 at about 30MPH and that should make the trans shift.

 

[sblake01]

I know this is a 6 month old thread but have you found a solution? Have you checked the 3-4 shift solenoid? Mine had stopped shifting into overdrive. I replaced the solenoid and the shift is back.

 

[CalgaryRanger]

what was the solution?