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Discussion Starter #1
Now that I’m going to let my kid drive my ’93 LWB (beforesomething else goes wrong…), I need to adjust the driver’s seat because he’s 3in taller than me. But I’d ALSO like to be able to adjust it back again for me.
I did it years ago by jumping the plugs in the harness witha car battery and some leads I made (I un-plugged the harness from the ECUyears ago because it went haywire, like they all do), but I just ran across adiscussion where a guy just installed relays under the driver’s seat splicedinto the wiring between the seat-control switch and the seat motors, bypassingthe ECU entirely. I downloaded a simple wiring diagram he made up that showsthis, but there was little write-up andno pics.
It makes sense to me IF there is power coming OUT of theseat controller going TO the ECU…so there is where you’d isolate the ECU andsteer the switch-power to your relays.
Can anyone confirm this plan, or comment on it’s feasibility?

 

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1970-1995 Range Rover Classic
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81 Posts
Cleaning the carbon buildup on the switch contacts will restore the switches functionality. It's a little difficult as you'll have to keep track of all the tiny springs and ball bearings. This repair will also enable the seat switches memory for 2 different seat positions. Take your time. Difficulty level 3 on a 10 scale. Good luck.
 

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1970-1995 Range Rover Classic
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I've seen many of the seat ECU's destroyed by the memory battery failing, then oozing acid onto the board. If you want memory functions to work, make sure that hasn't happened, and replace the battery.
 

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Discussion Starter #4
I'm sure my ECU is toast, that's why I un-plugged it years ago. I don't care about memory functions, I think they're over-rated. What I'd LIKE to do, is use the controllers and have them hooked to relays that are then hooked to the motors, bypassing the ECU completely.
 

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1970-1995 Range Rover Classic
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I've "hotwired" them before, but not by skipping the ecu directly. I can't help but think that the ecu plays a bigger role than just memory functions. Possibly seat calibration? Maybe mirror controls?

I know your wanting to dump the ecu, but have you cracked the case on it? It's a good bet that the memory battery failed, and only a couple circuits were damaged. Might be an easy fix with some solder, or at least easier than installing DIY relays under a seat. Sapelo Rover has a pretty good write up on his repair, which seems to be the common failure. https://www.rangerovers.net/forum/8-range-rover-classic/66777-driver-seat-ecu-repair-diy-replacing-3-6v-battery.html
 

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2006-2009 Range Rover MkIII / L322
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If the circuit board in the seat ECU is too far gone or you don't want to deal with repairs it can be bypassed. I removed the ECU from under the drivers seat and replaced it with eight standard relays. I used the existing wiring harness and connectors to connect the existing seat switch to the motors that move the seat. This option does remove the memory function. It also eliminates the ability to remotely adjust the external mirrors since they are also controlled through the ECU. However, I just adjust them the old way - reach out the window and move them manually. I've successfully used the relay pack alternative in both of our 95 Classics - a SWB and a LWB.

The passenger seat doesn't use an ECU or relays and the full amperage goes through the switch contacts. Cleaning the contacts as previously suggested is usually all that's necessary.
 

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1970-1995 Range Rover Classic
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Pull the seat memory battery by cutting the two pins or desoldering, clean the board and see if it works. No memory (which was already gone once the battery died) but mirrors and seat adjustment should work if the contacts were fine.

Otherwise try to find a way to jump the pins or try aussiebushman's DIY switch fix.
 

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Discussion Starter #8
If the circuit board in the seat ECU is too far gone or you don't want to deal with repairs it can be bypassed. I removed the ECU from under the drivers seat and replaced it with eight standard relays. I used the existing wiring harness and connectors to connect the existing seat switch to the motors that move the seat. This option does remove the memory function. It also eliminates the ability to remotely adjust the external mirrors since they are also controlled through the ECU. However, I just adjust them the old way - reach out the window and move them manually. I've successfully used the relay pack alternative in both of our 95 Classics - a SWB and a LWB.

The passenger seat doesn't use an ECU or relays and the full amperage goes through the switch contacts. Cleaning the contacts as previously suggested is usually all that's necessary.
What did you use as a power source to the relays?
 

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I can confirm that if you can find the seat harness from an early truck with power seats but no memory eco, it's 80% plug and play. I think I had to change the connector from the passenger side. There is nothing in between the switch and the harness coming from the truck, just the wires of the harness.
 
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