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Discussion Starter · #1 ·
Is there a way besides the dealer to program the BCM for towing. I was informed once I added the hitch and wiring harness I would need to have the BCM reprogrammed so the rear park sensors and air springs would be re-calibrated for towing.
 

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No, that's not necessary at all. The car can sense when a trailer is hooked up via a series of pulses that it sends out along the trailer taillight wires. Assuming the trailer uses standard incandescent bulbs, the car will know there is a trailer attached and will adjust your shift points and turn off the rear PDC. The air suspension adjusts the height whether you have a trailer attached or not. Now, if the trailer uses LED tail lights, that's a whole other bag o' worms. You'll need to fool the car into thinking a trailer is attached... Plenty of threads on the web about how to do that with resistors and relays.
 

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Discussion Starter · #3 · (Edited)
Okay thanks. This is what Atlantic British has in their instructions as the last step.
"#21. If your vehicle was not already configured for towing, you must have the body control module re-configured for trailer ball at a Land Rover dealer or Land Rover capable shop or someone who can access the module with a diagnostic scan tool."
 

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That's strange... I've never heard of that. And I purchased the Atlantic British wiring harness for my LR3 as well, but certainly don't remember anything in the instructions about having to configure the BCM. If you find out more, please let us know.
 

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Nope I've never done this and have have towed with RRS and LR3 with no updates, the transmission programming is independent and the module knows based on engine load, acceleration and TPS if there's a trailer behind you or now - will select a trailer / tow shift program to upshift late so the engine is always in the power band when it gets into the next gear, this dramatically limits the number of downshifts and trans heat.

They really tow amazingly well, good luck!
 

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Discussion Starter · #6 ·
Well I towed with it for the first time last night. It really pulls nice. We pulled our pontoon in from the lake for the season. The LR3 pulls a lot nicer than our DII pulled. No problems with the setup except the trailer has LED lights and they would pulse slightly when connected. The lights lit up like normal but had a slight pulse to them. Almost a good thing because they are more noticeable. Kind of like what you see on some motorcycles to get other driver's attention. The park control did go off when reversing with the trailer connected but all I needed to do was press the park control button when it would first start alarming and that solved it. I'm going to buy one of these which should solve the light problem. Trailer Connector Adapter w/ Lamp-Out Sensor Bypass - 7-Way RV to 7-Way RV - Vehicle End Tow Ready Wiring 20142
 

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I used the AB harness for my LR4 and did not have to reprogram. The only place I saw reprograming was with dealers selling on EBay. I installed my wiring with brake controller for a 7-pin flatbed car hauler and the 4-pin boat trailer. I have had no problems. They have a trailer adapter that fits on trailer for recognition, but do not need. But do have to turn off back up sensor a few times when I back-up. Relearning fast back-ups.
 

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Hi lr3 guys!
I'm a regular in the discovery 2 discussions.
Had a client come to me with a 2005 lr3 for a trailer hitch and wiring. Installed the hitch and plug and play harness from A.B.
All was going fine until I read the last step of the instructions about programming the b.c.m. For trailer towing.
I referred to this thread to verify that no programming was needed.
Thanks for the help ����
 

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It's quite possible that this is just redundant computer programming on LR's part with BCM options.

The only trailer functionality in the LR3 RRS is transmission (activated by load, standard feature designed independently into the ZF 6HP trans and trans sensors) and lights, which I know of.

Electronic trailer brakes are a pass-through to the Ford harness under the dash for electronic trailer brake controllers which I've installed and used on the RRS and LR3.

I installed the trailer electrics kit on each and didn't need any programming.

Actually fun fact, I used the RRS trailer harness on my LR3 (different LR part numbers) with no mods. Glad I ripped it off before I sold the sport!

The difference is that the sport combines the driver side signal housing plug into the trailer harness (or vise versa) due to smaller housing and space available. The LR3 has enough space for 2 large rubber grommets so I didn't even use half the RRS harness (unfortunately had to cut the unused plugs to get it to fit - ouch!)

Anyways, my trailer signal indicator on the dash works perfectly as do electric brakes and the modified trans shift programs - never touched the BCM programming on either vehicle.

FWIW the light pulses through harness are both on the flat-four connector AND the RV connector, and are only visible with LED trailer lights. Once the car "goes to sleep" they turn off. If you "wake it up" ie. open a door, and the Land Rover logo displays on the nav screen... then your trailer lights will be blinking again. Kinda interesting, I'd love to know what's going on there but everyone thinks it's cool and it is a good roadside visibility "feature".
 

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I tried turning on the "Trailer ball" feature in the programming and saw absolutely no change in pulling two different trailers, so I turned it back off...

Not sure what it does.
 

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So have you towed since you turned on the BCM? I'm having the same issue with the blinking lights, I've added relays and I bought the 7-way from E-trailer and still the lights blink?? I've got a 2006 LR3 and I put in the Atlantic British harness.
 

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Unfortunately, I've read on other boards that the particular adapter listed above will have no effect on our issue. The only fabricated solution I've seen (beside the obvious DIY path) costs hundreds of dollars. :(
 

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Just to clarify for the purpose of completeness on this thread, there are two different issues. The first issue has to do with the LR3 actually detecting a trailer and adjusting the shift patterns accordingly. This is done through sending a series of electronic pulses to the trailer light pins in order to see if there is a load attached. If it detects a load (i.e. a light), it assumes a trailer is hooked up and adjusts its parameters. Since LED lights are such a tiny load, the LR3 does not detect them and will not go into "tow mode". This issue can be solved by wiring a couple of load resistors (or any type of load including incandescent bulbs) into an external box and attaching it between the LR3 and the trailer.

The other problem is a result of the pulses that the car sends. While incandescent bulbs require a lot of power to get them to illuminate, LED bulbs require very little. Thus, these small pulses that the LR3 sends are not visible with incandescent bulbs, but are visible with LEDs. There are two ways to overcome this. The first is to simply turn your lights on. :) The second is to wire in a relay so that the trailer never actually sees the pulses.

Hope that helps. There's a lot of this info over on the disco3 board as well.
 

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I have a flat-bed trailer with LEDs with 7 way plug and a boat trailer with regular lights on a 4-way. No problems with either. But I have an LR4 which has a 4 way plug and a 7 way. I bought the wiring from AB and it went to both and have not had to do any reset. The trailer ICON flashes with the 4 way plug not the 7 way ( because of LEDs).
 
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