i know its an unusual route to take, i replaced the brake master cylinder on my 1987 city e with an earlier type the type 2, ( it was cheap ) the type with the black switch in the body, as opposed to the one with the switch in the cap, type 3.
but i need info on how to connect up the failure switch as i put bullet conectors on my existing ones, pluged them in and the failure light comes on constantly. but i have perfect brakes, in face they are the best ever - so how do i connect them up? should i join the two together on one side of the switch, then earth the other??? any help would be appreciated. thankyou.
brake failure switch - type 2 master cyl
Started by
m1n1
, Feb 06 2006 05:36 PM
2 replies to this topic
#1
m1n1
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Posted 06 February 2006 - 05:36 PM
#2
Dan
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Posted 06 February 2006 - 06:10 PM
<sigh> I wish they didn't put that picture in Haynes saying 'this is a type 2 master cylinder, this is a type 3 master cylinder...>
It's a completely different system. The body mounted switch is a PDWA and it tells you when one part of the system has less pressure than the other when you apply the brakes. The cap mounted switch tells you when the fluid in the system is low and it's used in reservoirs which have seperate chambers for each of the braking circuits so that a leak in one won't drain the other (incidentally the reason that they started using this type of cylinder is that it became a legal requirement to have independant fluid supplies so your new system may not pass the MOT if you had the later type originally).
Ditch the black wire from the connector and just tape it back to the loom with the end taped up leaving the black/white wire connected. The system should work fine now but you can only test if the differential switch is working by bleeding the front or rear brakes really.
This master cylinder may mess up your brake line pressures as the one it replaced had a stepped bore so that the rear and front systems operatoed at different pressures. The one you have fitted is single bore so your brakes may not work as they did. Also because it was designed for drums all round and you have discs and drums the line pressures front and rear will always be different so there's a chance the PDWA will light up every time you apply the brakes which is also an MOT fail. If your brakes work better with this type of master cylinder it could point to your FAM7821 valve being dead.
It's a completely different system. The body mounted switch is a PDWA and it tells you when one part of the system has less pressure than the other when you apply the brakes. The cap mounted switch tells you when the fluid in the system is low and it's used in reservoirs which have seperate chambers for each of the braking circuits so that a leak in one won't drain the other (incidentally the reason that they started using this type of cylinder is that it became a legal requirement to have independant fluid supplies so your new system may not pass the MOT if you had the later type originally).
Ditch the black wire from the connector and just tape it back to the loom with the end taped up leaving the black/white wire connected. The system should work fine now but you can only test if the differential switch is working by bleeding the front or rear brakes really.
This master cylinder may mess up your brake line pressures as the one it replaced had a stepped bore so that the rear and front systems operatoed at different pressures. The one you have fitted is single bore so your brakes may not work as they did. Also because it was designed for drums all round and you have discs and drums the line pressures front and rear will always be different so there's a chance the PDWA will light up every time you apply the brakes which is also an MOT fail. If your brakes work better with this type of master cylinder it could point to your FAM7821 valve being dead.
Edited by Dan, 06 February 2006 - 06:13 PM.
#3
m1n1
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Posted 06 February 2006 - 08:30 PM
thankyou for your advice, i have never had such a proffesional responce. to be honest, the testers at my local station are animals.. so no problems there then lol!
you are right about the valve, it was dribbling fluid out the side. replaced that at the same time as the master.
thankyou dan.
you are right about the valve, it was dribbling fluid out the side. replaced that at the same time as the master.
thankyou dan.
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