Results 1 to 8 of 8

Thread: Wiring weight reduction?

  1. #1
    Join Date
    Apr 2019
    Location
    Australia
    Posts
    4
    Total Downloaded
    0

    Wiring weight reduction?

    Hello all!

    I’m looking for some help, I’ve got a p38 1995 4.6L auto that I’m looking to reduce to a running chassis.

    Im after as much info as I can so I can cut the body off, reduce wiring down to absolute minimum to run without going into limp mode.

    Only plan at this stage is to have gauge cluster and steering column.

    What can I cut out? And what do I need to keep?


    Cheers.

  2. #2
    Join Date
    Jan 2016
    Location
    Netherlands
    Posts
    880
    Total Downloaded
    0
    That's a tall order

    I am not sure what it is you want to keep from/in the car and such. If you want to keep all the other P38 parts in place, such as the engine with it's ECU etc. then there is not a lot you can cut out actually. the BECM, as you may or may not know runs everything in the car. The cauge cluster, the windows, the lights, the horn, well. everything. also, the ECU must talk to the BECM because of the anti-theft system. If you really want just a running chassis which is never going to have any of the old functionality (that is including horn and lights and so on) then you could theoratically pull all that wiring out, remove the outdoor stations (since they are in the body they will be gone anyway) and remove all the cabling to them, all the way from the BECM plugs. I am sure the dash will throw heaps of errors but it should not affect the engine. Also, the ABS/ETC, EAS, cruise control and a few other things are run through the BECM which can be removed but might need fooling (see below). Having no ABS/ETC will throw your dash into a christmas tree but last time I had problems with the system, it did not affect the car in any other way.

    The climate control can be fully removed including all it's cabling as well.

    What you can't remove is the BECM itself, the ECU, the autobox computer (including it's connection to the becm), also do not remove the sensors! When and if you remove the EAS the suspension will stop working but you could manually inflate the airbags to a preset height. If you go for springs then you don't need it at all but remove the EAS requires a removal kit to fool the EAS computer. The low range controller needs to stay as well including it's connections/wires. unless you do not want to use low range that is.

    Mind you that the P38 measures everything so you will get constant door, rear, front whatever open errors and such so you would need to fool all those sensor readings for the becm or the dash will just not shut up.

    So, if your goal is to use a P38 as platform for some go cart, I would really just put in a megasquirt and be done with it (and figure something out for the dash cluster) because altering all this is a helluva job If you have other plans, please let us know and I am sure we can think along.

    Cheers,
    -P

  3. #3
    Join Date
    Apr 2019
    Location
    Australia
    Posts
    4
    Total Downloaded
    0
    that’s some great info thank you!

    I want to slim what I can down for a farm car project.

    I’ll have to look into the megasquirt, might be an easier solution.

    It sounds like I’m not able to remove much at all.

    I think I’ll have to slowly remove all the wiring and trick what’s simple and bundle the remaining.

    What’s the best software to monitor errors as I start pulling this car down?


    Cheers

  4. #4
    Join Date
    Jan 2016
    Location
    Netherlands
    Posts
    880
    Total Downloaded
    0
    Well, if you want brake lights, you need the BECM just to name one thing. The brake pedal switch is not made to handle large currents. You could use it to power a relais to get brake lights, just to give you a workaround example.

    The best software, that is more difficult. You need a device really since standalone software is not available afaik. Since you are gutting the car investing in anything decent is probably not worth it, I'd see if you can borrow a nanocom or something like that.

    The BECM is not very watertight so removing the body and placing it "anywhere" on the chassis is probably not going to last long.

    Go megasquirt, wire up what you need to keep using a relais between the switch and the lights (also, no indicator blinking since that too is done by the BECM) and forget about the dash cluster or wire it into the megasquirt for rpm's but I would not even know how to do the speedo...

    Also, the brakes are not vacuum powered but electrical and tied into the traction control and ABS system. Most components are connected to the body so a bracket would have to be made. I am not sure what would happen if you removed all the ETC stuff but I guess basic braking would keep on working. The main concern would be that the electric pump that pressures the brake system has a sensor and cut in/off point and I do not know what controls the pump, the switch directly or the ETC.

    I guess you got the car for free or was a left over or something but it would be easier to strip a disco or defender and keep it running than it would be to keep a p38 running, alas

    Cheers!
    -P

  5. #5
    Join Date
    Jun 2018
    Location
    Redesdale
    Posts
    1,524
    Total Downloaded
    0
    Quote Originally Posted by Jas269 View Post
    that’s some great info thank you!

    I want to slim what I can down for a farm car project.

    I’ll have to look into the megasquirt, might be an easier solution.

    It sounds like I’m not able to remove much at all.

    I think I’ll have to slowly remove all the wiring and trick what’s simple and bundle the remaining.

    What’s the best software to monitor errors as I start pulling this car down?


    Cheers
    IMO by the time you get your megasquirt and whatever software tools to moniter the rest of the car, you may as well go get an old D1 you will still have change in your pocket AND a p38 still
    That way you can REALLY strip it to bare chassis and build whatever mad max rig you desire! Go for a carb one if you want simple but an efi disco will still be simpler than your P38.
    I love the idea of farm rigs and stripped back 4x4s into tractors etc but i sure as hell wouldnt be starting with a p38 as my base.

    Make sure you post pics once you start your project Wiring weight reduction?

    Cheers Jim

  6. #6
    Join Date
    Apr 2019
    Location
    Australia
    Posts
    4
    Total Downloaded
    0
    Thanks all, I’ve been taking all these comments and learning what I can about each device.

    Seems like a lot of problems cutting this car down. The Rover was near on free, which is why it’s the starting base.

    I think I’ll give it a crack, see what I can slim up on it.

    Looks like I can remove the BECM completely by modifying the ECU or signal to the ECU. Seems to be 2 methods to this.

    Rewiring the starter relay would be required, as would the ignition power however no real problem in that.

    That will cut out any alarm state and EKA code resync issues. In turn I’ll lose any diagnostics options.

    Running external temp, oil pressure and rpm gauges isn’t a problem. $30 gets a cluster of manual pods from eBay to monitor vitals.

    Electronic braking maybe an issue?

    Auto ecu could be another, unsure at this stage if i can power externally and run it standalone, bit more research to go yet.



    Thanks for your help! Any more suggestions or hiccups please keen them coming!

    Cheers

  7. #7
    Join Date
    Feb 2013
    Location
    Gosford, NSW, Australia
    Posts
    2,556
    Total Downloaded
    0
    As long as you don't need indicators, or lights (including brake lights as prelude said), or wipers it should be OK to remove the BECM.

    There are probably other things as well

    Good luck !

    Steve

  8. #8
    jsp's Avatar
    jsp is offline Master Silver Subscriber
    Join Date
    Apr 2007
    Location
    South Australia
    Posts
    934
    Total Downloaded
    0
    seen it done where the gems ecu was sent to a fellow in Sydney who makes them run standalone, and a vaccum brake booster setup was cludged on, but all the body work was tube and checker and raised 6 foot up for pulling boats out....

    Personally I would pick up a d1 or series if your hell bent on a paddock thrasher surely someone will swap for a running P38....if the motors not cooked theres enough people looking for 4.6's (if its not a 4) who might swap a car for it.

    2007/2002/2000/1994/1993/1988/1987/1985/1984/1981/1979/1973 Range Rover 1986 Wadham Stringer
    and a Nissan Cube............
    South Australia.

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Search AULRO.com ONLY!
Search All the Web!