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Discussion Starter · #1 ·
Hi,

Yet another issue I need to sort on my ‘08 and wondering if anyone else has had the same. I’ve been chasing a parasitic drain and uncomfortable drive for a while and discovered a non oem trailer harness fitted and an ecu that had been spliced into the rear brake lights. There was corrosion in the ecu, so I whipped it all out and bought a westfalia oem trailer harness and ecu. Much more comfortable to drive andcar now recognises a trailer when it’s plugged in. But now there’s an issue with when there’s nothing plugged in. The trailer light on the dash occasionally goes on and off as though the car is registering something connected. I have swapped the tail lights out with 2010 style leds with resistors and mother boards from Powerfukuk. Could this be interfering with it? For now I have disconnected the white trailer block in the rear, but I would rather it was working 100%. I checked the fuses and they’re ok. There’s a relay but sure how to test it.
 

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Not following you, why do have an uncomfortable drive related to hacked up wiring?
 

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Discussion Starter · #3 ·
Not following you, why do have an uncomfortable drive related to hacked up wiring?
Good question, but it feels like the car gear ratios and stability are harder when the trailer light is occasionally going on and off. When I unplug the trailer electrics it’s comfortable by comparison. Although I was under the impression the 08 L322 didn’t adapt to trailers etc so not sure if I’m imagining it. I’m getting a fault code for the rear right tail light and the trailer electrics connect to that, but can’t find anything wrong with the light or connections. Could it be a voltage issue interfering with the trailer module?
 

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2007 Range Rover 4.2 SC V8
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Trailer harness runs through the rear by the spare tire. I believe there is a connector in that bay then up to the relay. Check the relay. I would suspect a short or bad relay. What do your lights do? these MYs use a hall effect brake light switch instead of the older mechanical one. I found my failed and the brake lights would not shut off once initiated... drove it for a few weeks before I noticed 🙄. could be causing some grief. While I've never had the joy I have heard one bad bulb can cause weird things - but it sounds like you're already on that. Another thought (havent towed so havent paid attention) does it have a 'tow mode' switch like trucks do?
Lastly, any codes?
 

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Discussion Starter · #5 ·
Trailer harness runs through the rear by the spare tire. I believe there is a connector in that bay then up to the relay. Check the relay. I would suspect a short or bad relay. What do your lights do? these MYs use a hall effect brake light switch instead of the older mechanical one. I found my failed and the brake lights would not shut off once initiated... drove it for a few weeks before I noticed 🙄. could be causing some grief. While I've never had the joy I have heard one bad bulb can cause weird things - but it sounds like you're already on that. Another thought (havent towed so havent paid attention) does it have a 'tow mode' switch like trucks do?
Lastly, any codes?
Hi, thanks for posting. I recently reconnected the white block connector as the previous owner had spliced it to wire in a non oem trailer module. At the moment the current setup is a new westfalia oem module and harness connected to the white block connector. From there, there are two 2010 style brake light units bought from PowerfulUK that seem to work fine. They have a resistor and a module spliced in right before the light to stop funny blinking etc. Could it be the resistors etc confusing the trailer module? There’s no tow mode but the car recognises when a trailer is connected. Fuses and relays look fine.
 

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I would definitely suspect that. Remove them and see what happens?
 

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Discussion Starter · #7 ·
I would definitely suspect that. Remove them and see what happens?
I was trying to avoid that as it will involve removing the resistors and motherboards. But assuming it is that, is there a fix? Eg another resistor on the return to the module to make it think the voltage is normal?
 

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I was trying to avoid that as it will involve removing the resistors and motherboards. But assuming it is that, is there a fix? Eg another resistor on the return to the module to make it think the voltage is normal?
I'm sorry but I just don't think I should be answering that. I don't know and don't want to give poor advice. My suggestion would be to get a used module and see what swapping it does? Saves you the headache of taking everything apart?
 

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Discussion Starter · #9 ·
I'm sorry but I just don't think I should be answering that. I don't know and don't want to give poor advice. My suggestion would be to get a used module and see what swapping it does? Saves you the headache of taking everything apart?
I’ll try that. From what I can tell it is likely because the module is picking up spikes in voltage likely coming from the led light. Ultimately I’ll have to figure that out. Do you know if the 08 adapts to anything when it senses a trailer? I know the 2010 locks the suspension, adapts the gearbox ratios etc. Does the 08 do the same or is just parking sensors?
 

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I do not. I'd be looking for an overdrive mode being enabled in the trans.
 
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