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john elmes

Retro fitting ABS to defender, one wire to go!

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Before we start, i am retro fitting ABS to a defender, chassis up build, so don't try and persueded me not to, its too late, 95% of the way there.

Ok, i have late TD5 ABS axel's, the actuator, all plumbed in. I have the ABS loom from a TD5 defender, with ECU and so far,  worked out all the wiring, dash lights, loom etc etc. But i am fitting this to a 300tdi loom, ie no ECU, and because of this i cant connect one wire, the wire that goes from the ABS loom to the TD5 ECU. Does anyone know what purpose this wire has , and if the ABS will work with out it connected? The wiring diagram does not seem clear on what this wire does, feed information to the Main ECU for control of engine speed / diagnostics or feed information from the main ECU to the braking ECU, or something else?

One other question, obviously i am very aware that this is braking and vital it works properly. But i have been told that as a saftey feature, Land rover designed this, that if ABS electrics should fail, the brakes revert back to working as none ABS braking, and therefor no worse that having none ABS brakes in the first place. I'm not using this to short cut the job, just interested if this is true. Can anyone confirm this from facts, not assumptions?

Any body go an answer to the wire or point me in the direction of any usefull acticles on this?

Thanks

Johnny

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Do you mean from the ABS ECU to the Main ECU? There are two wires shown, a Slate/Purple one and a Yellow/Pink one. The former is the same colour as another wire on the Main ECU that connects to the speedo, the latter is the same colour as the wire from the ABS ECU to the ABS Modulator.

I could guess that the ABS ECU wants to know the real speed (so it can work out when the wheel speed is relative to actual speed for traction control purposes) and the Main ECU wants to know when the modulator has activated.

But you shouldn't take that as advice.

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Totally up to you - however you may find, depending on where you are located and where the vehicle is registered, that you'll have some serious issues when involved with the law.

Apart from that, the plumbng is the easy part - sort of - but the ECU is different.

The RRC Softdash had ABS and a 300 Tdi. Have a look there I suggest.

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I have a 300Tdi soft dash.  The only electronics on the throttle system are the EGR controls.  There is nothing to the ABS/ETC ECU - it must come from the speed transducer or electronic speedo.  It may be different on the EDC equipped Tdis for automatic transmissions, especially on Discoverys.

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5 hours ago, Snagger said:

 it must come from the speed transducer or electronic speedo.  

This is my thinking too.

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Yes i have traced,  through wiring diagrams,  the one that goes to the speedo, i think the yellow / pink from memory, but will check. So i am thinking that on the 300 TDi, it takes its speed from the speedo  rather than the engine ECU, as on later TD5's My loom is in fact a 2006 defender, but i think they call it third world issue, not available in UK or europe. In effect its a 300tdi loom, (no ecu) but with the later TD5 connectors etc. I did not want the hassle of trying to make an ECU work with my V8 conversion, been there before on another project,  so plumped for the none ecu loom. Anyway, going off track now.

So i guess the ABS ECU needs the throttle position and speed for traction control, not braking, as you would not be excellerating and braking at the same time. Interesting, a bit more research i think. Thanks all.

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In hinds sight it would have been better to get an ABS 300tdi loom and strip the ABS stuff out of that in stead of a TD5 ABS loom. Oh well:)

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As I said, John, my '95 RRC has a 300Tdi and ABS/ETC, and has no input to the system from the throttle.  However, it is not the same system as used on Discoverys and late Defenders, so if you are using one of those rather than the RRC system, things could be markedly different.

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Update, for anyone else trying to do this.

Whilst trawling back through old copies of L/R mags, i found an article in LRM july 2013 (see it does pay to keep all those old copies, tell the wife!)

 Defender ABS Retro fit.

Fitting a TD5 ABS to a ROW (Rest of world) TD5 loom, which is what i have. Anyway, wont bore you all with detail, but it was done and sucessfull, by IRB developments. I just have to beaver away and find out some of these last few wiring details as the article was not that in depth.

I also have to work out how to wire in a OBD2 diagnostic socket as i had not thought about the fact that i way need to do some diagnostics or at least reset the ABS ECU.

 

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Well done, persevere. And thank you for the updates, very helpful. I'm going this route someday on a series station wagon, so this is valuable.

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