4HDD to 5HDD auto-trans swap

[tristan8]

Hi All,

My 4HDD auto-trans has died in my Oct-94 commodore VR wagon. I have a 5HDD trans from a VS (lexcan) in good nick.

From what I have gleaned from these forums the boxes are basically the same but the 5HDD has a 13-pin plug, 4HDD has a 12-pin plug. Based on this I have a couple of questions:
1/ Does anyone definately know what the 13th pin is for (there was some talk that it is for the trans-lock at high speed)
2/ Is it possible to run without the 13th pin plugged in or can you bridge it or similiar?
3/ There was some talk that you can change the bellhousing extension between the two so the 5HDD has the 4HDD plug. What does this involve exactly.

Any tips and answers from anyone who has done this swap appreciated. Thanks for any help in advance. Tristan

 

[stew_waz_ere]

yes it is very possible i just had my 4hdd replaced with a 5hdd and they said the same thing it might not work but i told them to try and 3 hours later it is in and working perfect!! im not sure what they done excatly but it worked

 

[tristan8]

ended up been a 6hdd but the swap was easy

just need to swap the housing extension (4 bolts) where the tail shaft joins as this is where the speedo sensor connects. the speedo sensor connector on the 6hdd is different to the 4hdd. might be best to change the tail shaft and extension housing oil seals when doing this.

despite the difference in the number of pins (6hdd 13, 4hdd 12) on the main connector, this plug is the same and nothing needs to be modified

 

[Slow VR]

I put a 5HDD in to replace my 4HDD. Same sorta thing had a 95 VR and used a VS Lexcen box. Didnt take to much notice of the pins but once it was all in, notice the engine light on for about 5 secs after starting it. I think i ended up with this fault code: Code 67 - TCC ON-OFF Solenoid Control Circuit - Auto Transmission Only

Which i think would of been for locking the torque converter up at cruise speeds?

 

[tristan8]

I put a 5HDD in to replace my 4HDD. Same sorta thing had a 95 VR and used a VS Lexcen box. Didnt take to much notice of the pins but once it was all in, notice the engine light on for about 5 secs after starting it. I think i ended up with this fault code: Code 67 - TCC ON-OFF Solenoid Control Circuit - Auto Transmission Only

Which i think would of been for locking the torque converter up at cruise speeds?

I definately do not have this problem. The TCC does lock up in the 6HDD gearbox, my car is a VR Series 2. If anyone has the wiring diagram for the VR gearbox we should be able to determine what the 13th pin is for. I have the VS wiring diagram which details all 13 pins. Anyone have?

 

[Slow VR]

Mine was a VR II also.

Here is the wiring diag.

http://laurenstephens.net/uploads/037067c337.pdf

 

[tristan8]

Interesting, the wiring diagram shows a 13-pin plug. Are you sure this is the wiring diagram for the VRII?

My 4HDD had 12 pins only on the gearbox connector. I didn't check how many cores the loom had.

 

[Morton]

I've stuck a 7HDD in a VR. Just swapped over the extention housing, and it worked a charm.

 

[94calais]

i've got a 94 vr also and the gear box died a little while ago and got a gear box out of either a vs or a vt can't remember which one it was but it went straight in, no problems

 

[DannyboyDS]

the VT auto needs a slight mod to fit though yeah?