car-breaker · Mar 5, 2015

Hi
our 99 disco 2 is suffering from the annoying 3 amigos,
my mate plugged his snap on diagnostics in and it said amognst other things abs sensor , code 134 shuttle valve switch ) electrical failure

we swapped the abs sensor (drivers front) which was chaffed and fitted a new shuttle valve (ebay £40)

After a week or so back came the 3 lights , read faults again and only code 134 shuttle valve switch ) electrical failure this time , but why ?? , ive just fitted a new one only 2 weeks prior

Any ideas Guys ??

cheers

Paul

sierrafery · Mar 5, 2015

Yes, quite common as the new SVS switch pack is not a cure cos i'm almost sure the old one is go0d too(unless it's ingressed with brake fluid which is not very common), the problem is within the big and expensive SVS assy where the contacts are weakened or an earth connection issue, there are two earth points in front of the airbox check if they are OK, here is the troubleshooting Land Rover Troubleshooting - Test Procedure And Instructions for Shuttle Valve Switches , if all the earths are OK you need to do the wiring mod option B, here is the explanation(quoting myself from other forum):

sierrafery said:
The SVS issue was explained many ways but never this way, i edited the internal diagram of the ABS modulator concentrating on the SVS module(SWO500040), i marked where IMO the problems usually are with orange but in case of oil ingress to the switches those resistances(with red) will be affected and the fault is the same, with purple are the external wires of mod option B, blue is the switch pack(SWO500030), there are two important notes on the original scheme:
* TOTAL RESISTANCE INCLUDING CONTACT AND CRIMP RESISTANCE: R<0.017 OHMS for the connection which gives the main earth(that big earth connector below the multiplug
**TOTAL RESISTANCE INCLUDING CONTACT AND CRIMP RESISTANCE: R<0.04 OHMS on the refference earth(ground) circuit from SLABS to pin 8 of multiplug

so there will be SVS related fault code if the resistances of the switch pack are out of range(which from MY experience is rare) and if one or both of those two earth circuit resistances are out of that "tight" range(thats the most common IMO), so taking with external wires the switch pack in series between earth and the SLABS ECU's SVS input the internal circuit of the modulator is bypassed and the only case in which the 3 amigos will come on again is if the switches will be ruined by fluid ingress ... that's why i'm saying that the brake fluid ingress is not the most common issue cos many of those who made option B didnt replace the valve seals, some of them nor the switch pack just made the wiring mod and they haven't seen the 3 amigos generated by SVS fault code again...i hope it makes sense

car-breaker · Mar 5, 2015

so , im best doing the wiring mod ? one wire to a earth and the 2nd wire into the loom of the connecter plug ? so if i sound thick but wiring is well beyond me

sierrafery · Mar 5, 2015

one wire to earth and other to the yellow/green wire which goes to the SLABS by cutting it and leave the side which is going to the modulator plug 'in the air'

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