Thread: Disco 4 LED Towing Module Problem

Correct. The vehicle pulses the Indicator circuit and if load is detected it will activate the tow based behaviours including shutting off the reverse sensors.

The module is a WOFTAM in a D4 - you have no need to isolate the vehicle from the trailer.
They were more useful in earlier vehicles where the LED lights on the trailer would pulse due to the vehicle checking constantly.

I highly recommend you remove the system, return the vehicle back to standard and return it for credit.

You do not need to do a single other thing to be able to hook up and tow... The remaining resistor set up will help kill the beep when reversing and a slight change to shift points etc. other than that you can tow anytime.

Originally Posted by Stevesonbeans

I'm going to try and just put a couple of resistors in line with the indicators

In Line usually means in series, the resistors need to be in parallel with the indicator LEDs. So one end of each resistor is to earth and the other end is to the lead that drives the LED for each indicator. You need it to draw more current, in series will mean less current.

Originally Posted by Stevesonbeans

"On the new vehicles there is no 2nd fuse box in the rear nor the need for the Diode."

This was the original thinking, I had my D4 connected without a diode for 18 months or so, but subsequent advice is to have the diode. You will get away without it, but if something goes wrong with the brake controller you could end up hurting your LandRover, so diode is a recommended precaution.

Your other box thing is not needed on a D4 as it already has separate circuits for towing.

Trust the advice you are getting here.

Regards
Gerry

Originally Posted by disco4now

In Line usually means in series, the resistors need to be in parallel with the indicator LEDs. So one end of each resistor is to earth and the other end is to the lead that drives the LED for each indicator. You need it to draw more current, in series will mean less current.

Actually, current flows along the path of least resistance - therefore in a parallel LED and resistor circuit, the resistor is bypassed effectively (LED has much much lower resistance). You need the resistor to be in series to do any good.

Edit -to be totally correct, when you have a parallel circuit, the total circuit resistance is less than the smallest resistor, but total circuit current increases.

If you put a load resistor in series to the trailer plug, the D4 will only register a trailer is connected when a trailer is connected. Put it in parallel on the trailer plug wiring and the D4 will always think a trailer is connected

Led has to be parallel to resistor otherwise car won't see trailer.
Led has low resistance and a voltage drop of only 0.6v but has a resistor in series in the light to prevent high current and subsequent failure.

The reason the car doesn't see the led lights is because they draw so little current. You have increase the current draw to the equivalent of a 21W bulb for the car to recognise the trailer.

Originally Posted by Geedublya

Led has to be parallel to resistor otherwise car won't see trailer.
Led has low resistance and a voltage drop of only 0.6v but has a resistor in series in the light to prevent high current and subsequent failure.

The reason the car doesn't see the led lights is because they draw so little current. You have increase the current draw to the equivalent of a 21W bulb for the car to recognise the trailer.

Sorry,
I just drew the circuit and see where I went wrong - in series the car WILL see the trailer (well, the load resistor), but the voltage drop over the load resistor will mean that the lights probably won't work. You need to have it in parallel (in vehicle it must be switchable) as you want to increase current draw, circuit resistance means nothing to the D4... it's been a long day and a few too many years since I did my DC theory

This was the original thinking, I had my D4 connected without a diode for 18 months or so, but subsequent advice is to have the diode. You will get away without it, but if something goes wrong with the brake controller you could end up hurting your LandRover, so diode is a recommended precaution.


Would you mind explaining how it hurts the landrover ? what the path for stray current getting back to the computertronics is ?
Thanks,
Steve

Also, we've installed a couple of 7ohm resistors in line on the indicators as a interim fix so i can get the thing registered. So I'm happy, but have also found that (the advice here was right) it wont be seen by the D4 so I will still have the reversing beeper screaming at me when trying to reverse.... not ideal.

I suspect I'm heading down the path of "Return" as it's all getting a bit too hard.

You didn't even have to fit anything to get it registered. Vehicle would still have worked fine...

You're on the right path with returning the item.