Center dif lock in low range option

[100 TD]

............ When in 4L mine locks me out of OD ..............
Anyway if I can get OD in 4L then that would pave the way for Marks t-case gears...

Electronics aren't my strong suit...so if anyone has a thought about this I'd appreciate it! 100TD?

It's all too long ago!
IIRC the low range detection switch on the transfer will send the signal which changes the shift points for low and high, which will also not allow overdrive. (This is the one you are thinking of unplugging)

IIRC, the pin 7 mod breaks(or makes) the signal to the 4WD control ECU that automatically locks the CDL when LR is selected. The signal still goes to the Transmission control ECU and changes the shift points.
SO I expect you would need to arrest that signal.
IIRC a Euro member of this forum did a write up on ABS control in normal, CDL, and LR modes and did a slight modification to the pin 7 mod and actually swapped pin 6 & 7 and put them back (or something like this) and disabled his ABS when CDL was on or something.
Do a search for that and have a read of his findings and I think you will get a handle on it, this may have held HR shift points as well. Just have a look at the wiring diagram and follow the LR switch to all it's ECU inputs. I expect if you break the connection to the Engine control module it will work. But see below.
So, if you interrupt the signal(or supply a positive or ground signal) to the tranny ECU you should be able to select OD in LO, easily doable.
However you will need to wire it to a flashing LED as a reminder that you have it activated.
You may get a result from disconnecting the LR switch or fitting a bypass switch BUT,
the reason for the pin seven mod was to do away with disconnecting this switch and allow everything else to function normally. By disconnecting or adding a switch I expect you will get OD back but lose other functions such as indication and not have LR shift points.
Give it a try.
This time of year I can't scan over all the drawings but if you read the post I mentioned you will understand which signal wire needs to be stopped or modified with a switch. (The Black/Blue wire)

 

[spressomon]

Thanks Warren. Its strange Toyota allowed OD/4th use in 4L on the later 80-Series per my friend Ali...no mods necessary.

I'll dig in an start trying to figure this thing out.

 

[nakman]

Thanks Warren. Its strange Toyota allowed OD/4th use in 4L on the later 80-Series per my friend Ali...no mods necessary.

I'll dig in an start trying to figure this thing out.

My 96 80 series with pin7 had OD in low range. I rode in another 96 80 series on a recent trip for 5 days, which had no pin7 mod, and no OD in low range. Just 2 data points, but it got me thinking maybe these trucks aren't that different here after all. So my initial reaction to "losing" this feature when going from a 80 to 100 was not entirely accurate, as I may have been reacting to the lack of pin7 mod only, and less of a wiring difference between the two. I'm pretty sure Ali has the pin7 mod..

Just to restate the intention here, I'd like to be able to retain an open center diff in low range, gain OD functionality in low range, and retain center diff lock control in high range. Being able to lock the rear with an open center would be an added bonus.

 

[spressomon]

Nakman,
After clipping the 7-pin wire years ago per Augie's post (as opposed to switching it like Campfire did...I've e-mailed him inquiring whether or not he can get 4th/OD in 4L with his switched 7-pin mod or not) I have complete manual control over the CDL in high or low range. And I can run the rear e-locker locked or open in either high or low range with the CDL locked or unlocked.

But the last coup de grace would allow me, et al, to get 4th/OD gear when in 4L.

I'm working on it...I promise this time

 

[nakman]

Well IMO 4th/OD in low range is the best mod of the bunch! appreciate the efforts, fun stuff.

 

[spressomon]

Well IMO 4th/OD in low range is the best mod of the bunch! appreciate the efforts, fun stuff.

And the ability to get 4th/OD in 4L paves the way for Marlin's new 25% lower gear set for the HF2A t-case with the ability to run 4th/OD in 4L at basically the same engine rpm as I have today with 3rd gear in 4L. Other than the cost of the gears I see it as a win-win for some of us...

 

[rusty_tlc]

I'm wondering if there would be a way to intercept the OD signal where the ECU connects to the trans harness.

 

[wildsmith]

I'm wondering if there would be a way to intercept the OD signal where the ECU connects to the trans harness.

If you intercepted the gearbox solenoid wires to feed them the correct combination for OD you'd also have to intercept the gearbox speed sensor signal and modify it to stop the ECU thinking something was wrong because the speed signal doesn't match the gear it has selected.

Intercepting pin 22 on connector E11 at the engine/ect ECU will prevent that ECU knowing L has been selected so OD should then work in L but other ECU's like ABS etc will still know to change behavior for L. You'll lose the L gear change points where it really holds on to 1st but a switch can fix that so you can choose behavior between OD and holding 1st.

 

[rusty_tlc]

It sure would be nice if someone could re-flash the ECU's in these trucks like they do for GM etc.
These guys do a lot of stuff for Lexus engines
http://www.spitronics.co.za/cms/index.php

 

[LandCruiserPhil]

Boy talk about making things complicated

Just pull the connector off the low range switch on the t-case..takes all of 1 minute

OD in low range, done

 

[rusty_tlc]

Boy talk about making things complicated

Just pull the connector off the low range switch on the t-case..takes all of 1 minute

OD in low range, done

How does that affect the shift points?

 

[wildsmith]

Boy talk about making things complicated

Just pull the connector off the low range switch on the t-case..takes all of 1 minute

OD in low range, done

True but then none of the ECU's know you're in low so ABS, ATRAC, VSC, AHC, any of those type systems might usually change behavior for low but won't.

 

[LandCruiserPhil]

How does that affect the shift points?

True but then none of the ECU's know you're in low so ABS, ATRAC, VSC, AHC, any of those type systems might usually change behavior for low but won't.

SHift may change just like an 80 but I dont see it as a big deal anyway because I use 2nd gear start unless needed in both the 80 and 100. The RPM change from 1-2 is 800 rpms more IIRC


My 100 is a 99 dont have ATRAC, VSC, AHC so im not sure on that. As for ABS I have never thought about it or noticed. I dont have it 80 since I went part time so I dont really thing about it when in the 100.???

 

[nakman]

Just to clarify... and someone correct me if I'm wrong here, but with a pin7 mod the shift points are lower compared to without one. Not sure on the 800 rpm number, but it's noticeable.

When I did the pin7 on my 80 series years ago I added in a switch for it, a switch I never used again.. the lower shift points made driving in low much better, in fact one of the added benefits of doing the mod in the first place, compared to just pulling the connector from the t-case.

 

[LandCruiserPhil]

Just to clarify... and someone correct me if I'm wrong here, but with a pin7 mod the shift points are lower compared to without one. Not sure on the 800 rpm number, but it's noticeable.

When I did the pin7 on my 80 series years ago I added in a switch for it, a switch I never used again.. the lower shift points made driving in low much better, in fact one of the added benefits of doing the mod in the first place, compared to just pulling the connector from the t-case.

Pin 7 lowers shift point on the 80 pulling the connector does not but does not give you OD on 96-97 only the connector. Not sure on the 100 series.

 

[spressomon]

Ok...pulled the t-case connector as Phil suggested and I have 4th/OD in 4L. It was late so I just did a couple around the block test drives...but no other issues.

I'll get to play with it on the trails hopefully this weekend and see if shift patterns are an issue or anything else.

Hopefully its just that easy!

Thanks Phil

 

[Nottajeep]

Ok...pulled the t-case connector as Phil suggested and I have 4th/OD in 4L. It was late so I just did a couple around the block test drives...but no other issues.

I'll get to play with it on the trails hopefully this weekend and see if shift patterns are an issue or anything else.

Hopefully its just that easy!

Thanks Phil

Ok, this seems like a weird situation... what speed will you be at in 4th gear 4L. Will the tranny wind up make it fairly noisy?

What trail conditions make this a good use?

 

[hoser]

Any thoughts/concerns on t-case temperatures at higher speeds?

 

[LCHardriver_02]

Yeah, how does speed in 4low 4th gear compare to 4hi 1st gear. Hoser makes a great point too.

RPM comparison too, please.

 

[spressomon]

Ok, this seems like a weird situation... what speed will you be at in 4th gear 4L. Will the tranny wind up make it fairly noisy?

What trail conditions make this a good use?

My main motivation for the 4th/OD and 4L is for installing the new Marlin 25% reduction gear set. With the ability to run 4L now in 4th/OD it makes it nice for those situations where you are between trail sections, as an example, and you don't want to stop and push into 4H...until you're through the next 4L section (typically because I have beno right on my bumper ) . So with Marlin's gears then 4th/OD + 4L would be very close to the engine RPM's I now have with stock t-case gears when in 4L and 3rd. Wouldn't use it alot...but nice to know I could.

Regarding heat: Increased heat output at the t-case was Campfire's concern. But they've been doing this in the 80 platform for sometime without any issues that I'm aware of. Again it wouldn't be used for extended periods of time...just between more difficult sections of trail where I don't necessarily want to stop and move to 4H.

Purportedly a vendor is testing the gear install...

FJ80 Crawler Gears | Marlin Crawler, Inc.