Thread: Transfer low high switch

You will find all diagnostic equipment read it the same, its not a high range or low range from a mechanical point of view.
Its computer talk.... high as in reading 1, low as in reading 0.

what Dazza said

Originally Posted by DazzaTD5

You will find all diagnostic equipment read it the same, its not a high range or low range from a mechanical point of view.
Its computer talk.... high as in reading 1, low as in reading 0.

Ok i understand everything you said but stills seems backwards to me, as if i open the door it says open, closed the door it says closed. So too me when its saying low on the nanocom but its actually in high seems odd to me and vice versa with low range. either that or i been using low range and high range around the wrong way the whole time

some interesting thinks i have found. On other forums some have said theirs read the same as mine others have said theirs are reading correctly ( high is high low is low). Another thing i came across was something to do with throttle response in both low and high range. Apparently some early td5 owners complained about jerky throttle response so LR in their innovative ways modified the system on some t5ds so that the low range damped response was applied to the high range to address the jerkiness. Other things people said was the switch may be sending out wrong signals due to being dirty or broken and if it reads low in high range there is a fault of some kind. Some even said and i find this worth looking into that theirs said low in high range and even tested the switch with multimeter and confirmed it as stuck in low and after cleaning it, it then read correctly and even said that it made a big difference.

*It seems backward to you because you are not a computer.
*I have been asked this surprisingly a lot over the years by Discovery 2 owners that have a "new toy" nanocom or others...
*I have no doubt some diagnostic tools prettify it for the user of the tool and see high = high range. low = low range.
*But if the nanocom is taking its info from... the BCM I guess, then its going to display high and low the same computer/electrical way the BCM does, which by the way is the same way the original dealer level Land Rover tool (T4) displays the switch.
*Correct the throttle response is different when in low range gear, but the computer does know which is which.
*The switch is a simple in or out.
*Swapping the wires around wont change how the computer sees it.

The hi/low input is monitored by the engine ECU, it is not linked to the BCU, unfortunately those who made the testers mixed up things cos it was supposed to show the gear's status not the signal's description, IMO the tester's builders could have made easily it to display correctly ''LOW" when the ECU gets the earth input, it's a simple software thing but as it started this way from the first Testbook tools it was not corrected even though it should have been cos that's how it's in the guides(wrong):

Originally Posted by NANOCOM - LUCAS TD5 DIAGNOSTIC.pdf

· Transfer ratio: This displays the state of the switch input from the high/low gear ratio selector. When it says HIGH, the high ratio gearing is selected, and when it says LOW, the low ratio gearing is selected

Originally Posted by Noisy

Had the nanocom out looking for a problem and was going through everything and noticed in the outputs section it says transfer then high or low. With the transfer case in high the nanocom says it is in low and low range on the transfer case nanocom says its in high.

Is this normal or is it a switch the wrong way around? Would this affect the cars performance by telling the ecu that its in low range when its actually in high if that is possible?

I have a feeling that the later nanocom firmware corrected this issue, now shows high when in high etc,I actually had a d2 that had done nearly 400000 km with the engine ecu running the low range settings, there was no wire running to the engine ecu too tell it to run high range map...
Unbelievable....

Originally Posted by shack

.... there was no wire running to the engine ecu too tell it to run high range map...
Unbelievable....

Quite unbelievable to run on HIGH map as long as there's no wire to the ECU cos exactly no input to the ECU means high range and an earth input from the high-low switch tells the ECU that it's in low...so no wire means that the ECU would not know if it's in LOW and stay in high cos that's the basic setting if you see what i mean