slabs ecu with something added

sierrafery said:

I rest my case then ..i dont want co complicate things...they are more complicated that they appear

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Well come on then - enlighten us,I've been dealing with Slabs faults on DII's since they came out and have managed to get customers cars back to a functional state.Its a bit late now as many of them have gone,but if there is more useful info why not share it ?

eightinavee said:

Well come on then - enlighten us,I've been dealing with Slabs faults on DII's since they came out and have managed to get customers cars back to a functional state.Its a bit late now as many of them have gone,but if there is more useful info why not share it ?

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OK... so i made some investigations using my engineering knowledge and an improvised bench with connectors from old harnesses(as a matter of fact i did this for various inputs in the ECM too, but that's a different story). I did this cos LR systems are a hobby of mine and i wanted to know why that big difference in price between the units as they can be find as new in some places and they appear just as superseeded part numbers.( a friend of mine needed one and I wanted to help him) .
e.g
1. SRD100462 ANTI LOCK BRAKE SYSTEM ECU | shop | www.lrseries.com | L. R. Series

2. SRD000070 ANTI LOCK BRAKE SYSTEM ECU | shop | www.lrseries.com | L. R. Series

3. SRD500070 ANTI LOCK BRAKE SYSTEM ECU | shop | www.lrseries.com | L. R. Series

Now…I used my well working 100462 and a working 500070 from other friend’s facelift and gave inputs in both units with a signal generator emulating the ”real life” while measuring outputs with oscilloscope based on the SLABS ECU input-output scheme from RAVE. After that i opened both units to try to figure out the “big “ difference. Visually I didn’t find nothing relevant just suspected an inhibitor circuit on the TC and HDC warning output. After many simulations that’s what I found out(though I can’t declare 100% that there aren’t some more improvements):

• on same inputs the outputs for the modulator ECM, BCU, etc, are the same except the TC and HDC warning output with earth path completed on difflock input ...that's why they do not come on on facelifts
• the ABS, TC, HDC are independent until a point then they are joint and work together on system’s or driver’s demand.
• there is a very small attenuation within the circuit on the wheel speed sensor input as to override the fluctuations on minor variations …I suppose to not trigger the 3 amigos immediately on air gap modifications when the reluctor ring gets a play due to the hub's bearing wear…BUT the “executive” outputs are the same for the modulator. That’s why with older units it happens that the 3 amigos are on but on a drive test all the systems are working normally(or if they are inhibited they are with both units) the only difference I found is in the warning lamps behaviour

It’s quite hard for me to explain the whole theory with proper technical terms in english but that’s the short story if I can name it so. In a nutshell: based on my measurements the BIG modification in the new unit is not for the system field behaviour but on the warning lamps management

Based on these facts my opinion is that it doesn’t worth a close to 100 quid difference just to not see the 3 amigos so often… and that small “boost” just gives a little more time until the hub will be more worn and then the 3 amigos will come on anyway.

I’ll stand corrected if I’m wrong cos i must state that i'm not a LR specialist just that i graduated avionics engineering but if you have specific questions I’ll be happy to answer if I can.


EDIT: AAA ..i remembered something which can be tested "in field" > due to that "signal stabiliser"(or how can i name it) the TC and the ABS kicks in faster/earlyer in the same conditions with old units ...which could be even better some times

Blimey ! you must have alot of time on your hands.... Not many would go to that much trouble,esp for a friend.I can see your point and how you got there but there I think there is more to it.Reason I would only go for the 500070 is that all the ones I have fitted are still working,some of there earlier ones failed again.And its not just related to tolerance of hub sensors.(With these I have scoped them and been unable to find any difference between the "faulty" one and the others on the car - or even the new replacement.)
I have also seen the earlier ones dump all the air out of the SLS at random times,and on other cars the TC becoming active at 60+ MPH without warning on a straight dry road.So you see whilst electronic testing with signal generators and scopes can be interesting and teach you how systems function,in practice with many multiple units the story can be different.
With so many of them being scrapped now it shouldnt be too hard to find a second hand 500070 from a breaker and be happy that it should last the rest of the life of the car.

what i can admit without remorse is that the practice usually overcomes the theory.... so i'm banking on your statement cos i dont have such field experience on this....as i said, it's just a hobby of mine

thinking about what you said...yes, there is a theoretical explanation for that improved reliability too... even if the outputs are the same i suppose that they've used better quailty electronic components which are more stabile... if i recall well i remember that i saw some tantalum capacitors in the new unit while in the old ones they were ceramics ... didnt cross my mind then that it could make the difference ...and i'm sure that there are other pn junctions which are latest technology too ... that's why the new units are more expensive then

... a "dispute" like that could have positive outcomes though

i can not do anything about car yet, because ive had an operation on my nee can not walk yet, if i get a second hand slabs ecu can i just plug it in, or will it need setting up on computer

you'll need to plug it in tester to sync some things...unless the donor car was exactly the same as yours(quite unlikely)

ive been looking at disco 2 2000 v8 today, first of all it got a slabs ecu srd000070 fitted with 2002 on it,ive done the technical bulletin ltb00060 22 jun 2007 and everything reads correctly so not done the modulator mod.ive also done technical information 70/07/04/nas 28 october 2004,cheching ohms at modulator and slabs connecter which all read correctly,computer still says front right wheel sensor to low, the sensor resistance is in limits, and also i get the same reading at the ecu, so there is no faulty wiring, i tried to be clever but it didnt work, i put the front left wheel sensor signal to both front ecu terminals, to try and fool the ecu into thinking the signals were correct but the abs light remains on, on live data the right front wheel sensor reads the same as the other three but it is slow to get there, should my idea of worked to turn the abs light off, this meaning the fault was in the right front or is there another fault ie, slabs ecu, how can i test the ecu to see if its faulty

you should have swapped the signals between them from left to right, not put the left for both cos if it's on both at the same time the resistance drops to half...if with inputs from sensors swapped at the ECU the fault still stays on the RH then it's the ECU at fault.... and be aware the ABS light will not go off untill you don't exceed 10mph...but if the reading is low it could be the hub at fault

been looking today at abs problem, put multimeter on both front sensor wires by the ecu in car, passenger side was constantly reading approx half of what drivers side was. i changed the passenger sensor for a spare i had,(second hand)but it looked slightly bent and after ten mph(approx) the abs light went out. looking at the multimeters the passenger was reading 3/4 of what the drivers side was. after seven miles i slowed down for a 30,(did not use brakes) and abs light straight back on again, it must be the sensor, so will have to get a new one

My vin number falls within the SLAB recall listed numbers (1999 Discovery TD5 GS)... are Land Rover still obliged to do the replacement if its not been done already? (free!!) cheers

I'm not sure, but the only way to no if its been replaced is to drop the ecu and look at the number, it says if the ecu as been replaced there should be a label on the slam panel, but mine does not, the ecu had been changed though

I apologize for my post to an old topic but it is helpful.

I confirmed today my Foxwell NT510 will change the old stored VIN on the SRS500070 SLABS unit to my own NAS SALTY VIN.
I couldn’t do that with my Nanocom.

Nice one ... though i'm wondering what's the benefit of this ?

I wonder what the benefits are of doing this also but I wanted to share this discovery... no pun intended. Lol