Thread: ABS Module - Need your Thoughts

Originally Posted by Graeme

the required 3K resistance across the open shuttle valve switches is sometimes open circuit after running the ABS pump for a short burst and 3K at other times. Hence there has to be a faulty connection inside the modulator that sometimes gets fixed by the vibrations.

Just been there...
All solved by two wires bypassing the internal socket and pin arrangement. Connect each of the 2 brown wires from the microswitches to pin 6 and a ground wire on the plug respectively. 3, 2 and 1K now measured with no, moderate and severe brake pedal pressure, and best of all, adios amigoes.

Cheers,

Steve

PICS!!!

I had constant 3 amigos problem for ages. Replaced pads & problem did not occur for about 3 mths. It has now started to come back & I am wondering if changing the rotors (well worn- machined once already) would help. Also "heard" that if you engage HDC it can help "free-up" shuttle valve. I am slightly spanner-impared but thought it was worth a mention.

Originally Posted by gofish

I had constant 3 amigos problem for ages. Replaced pads & problem did not occur for about 3 mths. It has now started to come back & I am wondering if changing the rotors (well worn- machined once already) would help. Also "heard" that if you engage HDC it can help "free-up" shuttle valve. I am slightly spanner-impared but thought it was worth a mention.

"exercising" the shuttle valve via the HDC down a steep slope every few weeks/months seems to keep the 3 amigos away for me.

Originally Posted by zzsteve

Just been there...
All solved by two wires bypassing the internal socket and pin arrangement. Connect each of the 2 brown wires from the microswitches to pin 6 and a ground wire on the plug respectively. 3, 2 and 1K now measured with no, moderate and severe brake pedal pressure, and best of all, adios amigoes.

Cheers,

Steve

That should be pins 8 & 9 (pin 6 is unused). The 2K reading is when 1 switch is open and the other closed which is a fault condition.

Originally Posted by Graeme

That should be pins 8 & 9 (pin 6 is unused). The 2K reading is when 1 switch is open and the other closed which is a fault condition.

Quite correct. Shuttle switches are between 9 and 8 (6,7 & 8 are all tied to ground on the circuit I have). My problem was episodic amigos almost at random in an '02 D2. Perhaps they were associated with bumps and sometimes braking. Speed sensors seemed OK and earthing of the modulator was also OK. With no brake pedal pressure the resistance between pin 9 and 6 (or 7 or 8 or earth) was infinite. Pumping the pedal brought on a mix of values down to about 1K. The diagnosis is therefore the switches - or was it?
It is possible to remove the switch assembly underneath the modulator without cracking the fluid lines (pic 1). The three socket head screws are easy to find and undo.
Embarrassingly, the switch assembly was full of sand but the switches seemed well sealed and testing resistance across the 2 pins gave 3k, 2K and 1K with no switch pushed, 1 pushed and both pushed in. No fiddling could make it go open circuit. The problem must be the pin connections and/or internal wiring.
I soldered 2 wires onto the brown leads coming from the switches (circled in pic) and ran them out 2 existing holes on the plastic plate (arrows in pic). Leaving the socket connected internally was to be a mistake.
The external leads were connected to pin 9 lead in the harness and the other to ground. Now, I had a 50% chance of bridging the switch internals correctly and of course it was wrong (ask me how). Quick reversal of the wires and all was good. 2 weeks now of no amigos, spinning it up on the gravel driveway confirms ETC still going. makes me wonder how many ABS modulator faults which don't get better after replacing the switch assembly are really internal connection faults.
HTH
Steve

while this has been done previously,,
its ALWAYS good to hear someone take these things on,
rather than give up and "replace",,

oh,, and Ta for the pics,,,,

I like the positive connection afforded by hard wiring from the switches directly to the harness, but as I'm hoping to be selling the vehicle at the end of the year, I think extra external wires might be off-putting to a prospective buyer so will endeavour to correct the faulty connection internally.