HDJ81 7-pin mod doable?
- Thread starter ikeedikeed
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
- Joined
- Sep 17, 2005
- Threads
- 110
- Messages
- 638
- Location
- Vancouver, Canada
- Website
- www.jjadventuretours.com
Why would you want to? You already have a manual CDL switch in your HDJ81. If you don't want it to automatically lock the center diff in low range just disconnect the sensor wire from the xfer case. Now you will only get center diff lock in low range when the CDL button is pushed.
The slee mod is only needed with ECU-controlled trannies. Unless you have a 1996-or later HDJ the tranny is entirely mechanical and this mod won't affect tranny shift points (which I assume is the point of the mod). I assume there is a different tranny shift pattern in the ECU for low range operation.
Last edited:
- Thread starter
- #3
I didn't know it was that simple. Thanks Jonathan.
Cruisin'
Out in the shop, building something cool!
You can do the same thing as Johathan suggested by disconnecting the pin 7 wire behind the kick panel. At this moment I can't remember which side its on, though i'm thinking right side. Accomplishes the same thing: Full control with the dash CDL switch. The centre is locked when you want it, and not when you don't. I can look up which module it is and which side its on if you need me to.
- Thread starter
- #5
I did the pin-7 removal version and it took less than 5 minutes and all you need is a pair of pliers. The transmission control relay is even easier to get to on an HDJ81 than on the FJ80 on slee's tutorial because you don't have to remove that silver box thing. The relay is behind the kick panel to the right of the gas pedal on the HDJ81. Pop the panel off, unplug the wiring harness from the transmission control relay and remove the small black wire with the blue tracer from pin-7. Plug the harness back in and pop the panel back on and you're done.
Never again will The Man tell me when to engage my CDL.
Never again will The Man tell me when to engage my CDL.
Last edited:
- Thread starter
- #6
Thanks for the help guys. I guess they both do the same thing.
Cruisin'
Out in the shop, building something cool!
Glad you got it sorted out, Greg. Not long after doing mine I pulled a heavy load up a steep and winding hill. Did it on low range with the CDL off, went up with the torque converter locked, and the tranny hardly heated up at all. Worthwhile mod in the right conditions.
- Joined
- Sep 17, 2005
- Threads
- 110
- Messages
- 638
- Location
- Vancouver, Canada
- Website
- www.jjadventuretours.com
How did you get your torque converter to lock on a 91 HDJ81?? Did you go up in 4th gear in low range? At what speed did it lock?
- Joined
- Sep 17, 2005
- Threads
- 110
- Messages
- 638
- Location
- Vancouver, Canada
- Website
- www.jjadventuretours.com
Yep, I guess pulling the pin has exactly the same effect as pulling the sender connection. Except pulling the sender takes 10 secs and if you want it working again you just plug it back in. I guess the only downside to pulling the sender might be the risk of corrosion, so you'd want to seal the male and female plus nicely.
- Thread starter
- #10
My torque converter locks at about 60km/h in high range. So, assuming low range is 2.48 reduction (I think it is), it should lock in low around 24km/h. I've never taken notice though. I'm usually going a lot slower than that when I'm low.
Last edited:
Cruisin'
Out in the shop, building something cool!
Jonathan, I got into 4th in LR for it to lock. Can't remember the exact speed, but it was somewhere in the neighbourhood of 30km/h. Greg's calculation makes sense.
See my Torque Converter locks at about 72kmh, I would assume it all has to do about tire size? My dads locks around 60 and he is running 16's and I am on the stock 15's.
I've always been mystified as to what "locking" really is in an automagic tranny, but mine with the 285 75r16's would always kick into 4th at 60 km/h, and even now with the 315's it still does it at 60 kmh.
Rim size (16 vs 15) has absolutely nothing to do with anything, except for clearing larger brake assemblies.
Cruisin'
Out in the shop, building something cool!
That is weird Christian. Tire size shouldn't affect it since the speedo is reading off the t-case, and the tranny doesn't care what actual speed you're going (tire size dependant), just what speed the tail shaft is spinning. When I put the larger rubber on, the speed at which the torque converter locks stayed the same.
Jeff, at 60km/h you're not going into 4th gear, what is happening is that you're already in 4th, and the torque converter is locking (it feels like another gear change). Once this has happened you'll notice that when you apply throttle that the rpm and speed go up at the same rate. When the torque converter is not locked first you'll see the rpm come up, and the speed follows. With the torque converter locked there is no slippage in the system, and as a result hardly any heat being generated. If you have a transmission temp gauge you can really see the difference when it locks up. The temps come down quite quickly.
Jeff, at 60km/h you're not going into 4th gear, what is happening is that you're already in 4th, and the torque converter is locking (it feels like another gear change). Once this has happened you'll notice that when you apply throttle that the rpm and speed go up at the same rate. When the torque converter is not locked first you'll see the rpm come up, and the speed follows. With the torque converter locked there is no slippage in the system, and as a result hardly any heat being generated. If you have a transmission temp gauge you can really see the difference when it locks up. The temps come down quite quickly.
