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Need some help with an EZ-TCI TCM with a 6.5 diesel.

I will have a look at that. I want to relocate the TCM from under the hood to inside the cab.

Would you have some experience with this combined with the GV OD setup? the instructions show two wires Pin 8 and Pin 9 jumped from the GV VSSB to the OEM VSSB and what looks line Pin 15. The GV unit has a speed sensor as well. I emailed them asking if this was to take the place of the output speed sensor on the trans but never got a response.


  • Gear Vendors 94-94 diagram.pdf
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On the OEM VSSB on pin 15 is a LT BLU/BLK wire.

That is the 4000 PPM speedo feed.

The TCU has a speedo output on pin 24.

Remove/cut that LT BLU wire from the VSSB conn. and connect

to pin 24 of the TCU.

Page 12 of the TCU manual shows how to set that up and also to calibrate if it is needed.
I think I missed the part on the GV instructions and just realized it from your post. I need to take pin 15 out of the OEM VSSB and move it to the GV VSSB. that should give me a working speedo using the speed sensor on the GV OD unit.

I wonder if I also need to change anything on how the TCI TCU gets it signal too. since it's using the rear output speed sensor on the trans. when the GV is turned on there will be a difference in the actual speed.
The GV unit changes the gear ratios like a transfer case would in low range.
I cannot find any verification that the EZ-TCU works with 4wd.
So that may be a problem.
It would work in HI range but what happens in low range?
I guess you could call them and ask.
Well fellas and fellets.. I figured I need to post an update since I seem to have run across an odd issue.

Now that Summer is here and I have the AC in the truck working things are starting to get heated up and worked harder. the wife and I were were out running errands the other day and all of a sudden I lost all gears and was stuck in first unless I manual shifted into second. I scooted along in 2nd gear till I could pull into a side street in town, stopped and connected the EZ-TCU handheld and tried reading codes... none... ok that's not good...

leaving the handheld connected, I put it into live data mode dropped it into gear and tried to go. at that point it began shifting like normal until right about a mile from the house. dropped into 1st and no more shifting other than manually shifting into 2nd. looking at the handheld display I quickly noticed that the TCU was not showing a MPH reading! Made it home looked everything over but didn't see anything out of the ordinary.

well today while out and about it did it again... drove fine all over town until I left the truck running with the AC for my wife as I ran into Harbor Freight for a quick impulse buy. I came back out and as we were heading across the parking lot I noticed the truck wasn't shifting out of 1st again... hooked up the handheld and once more there was no MPH signal though my speedo works (different sensor). I dropped the lever into 2nd and hobbled out of the parking lot and across the road to the grocery store where we had to do some shopping. I figured let the truck cool while were in the store and I will deal with it then.

Get done in the store and go to leave.. the truck drives perfectly fine till we get closer to the house. Looses MPH signal and downshifts to 1st without warning...

This happening could be horrifying if I was going 70 on the freeway! dropping to 1st without warning simply due to a sudden loss of speed signal.

I put the truck in the back driveway, got underneath and pulled the rear speed sensor from the trans. it did not look bad nor did it have any fluid leaking through the connector. Checked the harness up as far as I could without having to undoo the entire thing up to the TCU. everything looked fine. so I swapped the front and rear speed sensors in the trans since the front one was not being used.

Not sure if this will fix the problem but will eliminate if the sensor is bad. But I was reading online and it seems that these TCI trans controllers also don't like heat. well this thing is mounted on the inside of the drivers fender wall inside the engine compartment.

I am curious if others that run these EZ-TCI tcu's have run into issues with heat from the engine bay. @Will L. or @Hummer H1, would ether of you know others who might have run into this?

looking at it and the harness, it would be an undertaking to re-locate the TCU in the cab. I would have to ether extend all of the wires to make the harness longer (28 or so wires) or pull it completely out harness and all from the truck and attempt to re-route everything hoping I don't need to still cut and extend the harness!
I might try tomorrow leaving it idling in the driveway with the ac running in the heat of the day while putting the rear wheels up on stands. just keep monitoring it for signal loss while the engine compartment heats up. Then I can wiggle wires and what not and see what happens.

I've been trying to brainstorm ways to keep the TCU cool other than trying to relocate it if heat turns out to be the issue. when I brought the truck home, the TCU was inside one of those pelican plastic type hand gun cases with a hole cut out on the side for the harness and laid out right behind the drivers side battery. All I did was remove that case and make that area neat with the wiring. maybe if I put it back along with some insulation. that might help by taking longer to get heat soaked. Trial and error will be the key.
Well today I drove around in town, left the truck running with the ac on for about 7 minutes or so while I ran inside to get something. came back out and the truck drove fine. went gallivanting through town for a bit, stopped at a traffic light. as soon as the light turned green she was stuck in first once again! hobbled across the intersection and into a service station, turned off the truck and went inside for a drink. came back out and tried to leave... truck started shifting fine for about 8 blocks till I pulled back into the driveway. I feel like this is heat related.

I suppose I need to make plans to pull this TCU out and re-locate it into the cab and see if that helps things. might try contacting the company but not sure what they will help with other than tell me to send it in for repair or to purchase a new controller.
My truck has a B&M shift controller.
I think the only thing it controls is how firm it shifts gears.
There are three positions on the switch.
It was on position 2 when I got the truck. At times that seemed quite harsh so I moved the switch to position 1 which is suppose to be stock shift and I like that much better.
I also found out that the transmission in this truck had been a remanned unit from Browns Transmissions over in Billings Montana. That was accomplished a very few miles before I came into possession of the truck.
Why it has a transmission shift controller such as this is unknown to Me, unless, the previous transmission was going bad and someone thought they could fix it with such a controller.
And then it is mounted under the jockey box so getting to it to play is a real PITA.
Maybe someday I’ll clip them zip ties and extend it out where it can be messed with. 🤷‍♂️
Maybe the more harsh shift positions is for trailer haul mode or some such. 🤷‍♂️